Integrated Municipal Solid Waste Management Manual - Brazil

INTEGRATED MUNICIPAL SOLID WASTEMANAGEMENT MANUAL

In Latin Americanand Caribbean Cities

INTEGRATED MUNICIPAL SOLID WASTE MANAGEMENT MANUAL

IN LATIN AMERICAN AND CARIBBEAN CITIES(Based on the original edition: Manual Gerenciamento Integrado de Resíduos Sólidos, 2001)

1st EDITION – 2008

MINISTRY FOR THE ENVIRONMENTAND TERRITORY – ITALY

General DirectorCorrado Clini

Director, Division I, Environmentand Development Research DepartmentPaolo Soprano

Consultant, Division I, Environmentand Development Research DepartmentPierluigi Manzione

INTERNATIONAL DEVELOPMENTRESEARCH CENTRE, IDRC – Canada

Senior Program SpecialistWalter Ubal Giordano

Research OfficerAlicia Iglesias

Program AssistantClara Saavedra

Webmaster

María Noel Estrada

BRAZILIAN INSTITUTE OF MUNICIPALADMINISTRATION – IBAM

General DirectorMara Biasi Ferrari Pinto

Director, National School of UrbanServices – ENSURTereza Cristina Baratta

Director, Urban Development and the Environment– DUMAAna Lucia Nadalutti La Rovere

PUBLICATIONTechnical coordinationKarin Segala

Technical content – Update and AdaptationGilson Leite MansurJosé Henrique Penido Monteiro

Chapter 2 – CollaborationVictor Zular ZveibilSilvia Martarello Astolpho

Technical RevisionAndrea Pitanguy de RomaniKarin Segala

Translation from Spanish to EnglishLiliana Battipede and David Reed

Design and LayoutRoberto Tostes / Doble Clic Editoras

Publishing Coordination and Revision,English versionVíctor L. Bacchetta and Laura Pallares

Manual on municipal solid waste integrated management in Latin American and Caribbean cities /José Henrique Penido Monteiro …[et al]; updated and adapted by Gilson Leite Mansur and JoséHenrique Penido Monteiro; technical coordination by Karin Segala; translation by LilianaBattipede and David Reed. – Montevideo: IDRC, 2008.

264p.; 21 X 29.7cm

Adapted from: Manual gerenciamento integrado de resíduos sólidos, 2001.

1. Solid waste. I. Monteiro, José Henrique Penido. II. Mansur, Gilson Leite. III. Segala, Karin

(coord.). IV. International Development Research Centre (IDRC).

INDEX

PRESENTATION 6

PREFACE 12

1 The general situation of solid waste managementin Latin America and the Caribbean 141.1 Introduction 151.2 Regional Evaluation of Municipal Solid Waste Management

Services in Latin America and the Caribbean 151.3 Solid waste sector trends 22

2 Integrated Solid Waste Management 28

3 Institutional models and payment for services 323.1 Concept 333.2 Forms of administration 343.3 Payment for services 393.3.1 Guidelines for the calculation of a waste collection rate 42

4 Legislation and Environmental Licenses 444.1 Introduction 454.2 Legislation 454.3 Environmental Licenses 474.4 Regulations applicable to solid waste 48

5 Solid waste: origin, definition and characteristics 505.1 Definition of rubbish and solid waste 515.2 Solid waste classification 515.2.1 Potential environmental contamination risks 515.2.2 Nature and origin 525.3 Characteristics of solid waste 595.3.1 Physical characteristics 595.3.2 Chemical characteristics 625.3.3 Biological characteristics 635.4 Influence of solid waste characteristics on urban

cleaning system planning 635.5 Factors that influence solid waste characteristics 655.6 Processes for determining principal physical

characteristics 66

6 Solid waste quantity projections 70

7 Solid waste preparation and storage 747.1 Concept 757.2 The importance of appropriate preparation and storage 757.3 Characteristics of pre-collection storage containers 767.4 Domestic waste pre-collection preparation and storage 787.5 Pre-collection storage of street waste 807.6 Pre-collection storage of waste in low

demographic density and low-income areas 827.7 Pre-collection storage of waste produced by large

generators 837.8 Special domestic waste pre-collection storage 847.9 Special origin waste pre-collection storage 87

8 Solid waste collection and transport 908.1 Domestic waste collection and transport 918.1.1 Concept 918.1.2 Collection regularity 918.1.3 Collection frequency 928.1.4 Collection times 938.1.5 Restructuring domestic collection routes 948.1.6 Collection vehicles 1008.1.7 Tools and implements used by collectors 1058.2 Public solid waste collection and transport 1068.2.1 Concept 1068.2.2 Collection of waste gathered by sweeping 1068.2.3 Collection of waste from weeding and vegetation cutting 1078.2.4 Tree pruning waste collection 1088.2.5 Collection of rubble and other construction waste 1098.2.6 Special collections 1098.2.7 Vehicles and equipment used for collection 1108.3 Waste collection in tourist cities 1138.4 Solid waste collection in informal settlements 1148.5 Collection of medical waste 1158.5.1 Acknowledgement of the problem 1158.5.2 Segregation 1168.5.3 Separate collection of common, infectious

and special waste 1178.5.4 Vehicles for collection and transport 1178.5.5 Aspects of collection planning 119

9 Solid waste transfer 1209.1 Concept 1219.2 Types of transfer station 1229.2.1 Direct transfer station 1229.2.2 Station with storage facilities 1229.2.3 Alternative transfer systems 1249.3 Vehicles and machines for transfer stations 124

10 Street cleaning 12610.1 The importance of street cleanliness 12710.2 Waste found in the street 12810.3 Street cleaning services 12910.3.1 Sweeping services 13010.3.2 Weeding and scraping services 13610.3.3 Cutting services 13810.3.4 Drain cleaning services 14310.3.5 Market cleaning services 14510.3.6 Manual and mechanical waste removal services 14610.3.7 Beach cleaning services 14710.4 How to reduce street waste 15010.5 Street cleaning in tourist cities 152

11 Recovery of recyclable materials 15411.1 Concept 15511.2 Selective collection programs 15611.2.1 Selective door to door collection 15711.2.2 Voluntary Drop-off Centres (VDC) 15911.2.3 Segregator organizations 161

12 Solid waste treatment 16412.1 Concept 16512.2 Domestic solid waste treatment 16612.2.1 Recycling 16612.2.2 Composting 17012.2.3 Choosing a treatment option 17412.3 Treatment of special domestic waste 17712.3.1 Construction rubble 17712.3.2 Tyres 18212.3.3 Batteries and fluorescent tubes 18412.4 Treatment of waste from special sources 18412.4.1 Industrial solid waste 18412.4.2 Radioactive waste 18512.4.3 Port and airport waste 18612.4.4 Medical waste 186

13 Solid waste final disposal 19613.1 Introduction 19713.2 Impacts of inappropriate solid waste disposal 19813.3 Sanitary landfill 19913.3.1 Sanitary landfill site selection 20313.3.2 Environmental licenses 21113.3.3 Master plan 21313.3.4 Landfill installation 21513.3.5 Sanitary landfill operation 22213.3.6 Equipment 23213.4 Controlled landfills 23313.5 Environmental recuperation of refuse dumps 23613.6 The situation of segregators 23813.7 Special domestic waste disposal 23913.7.1 Construction rubble disposal 23913.7.2 Disposal of batteries 24013.7.3 Disposal of fluorescent tubes 24013.7.4 Disposal of tyres 24113.8 Disposal of waste from special sources 24113.8.1 Industrial waste disposal 24113.8.2 Radioactive waste disposal 24513.8.3 Port and airport waste disposal 24613.8.4 Medical waste disposal 24613.9 Sanitary landfills and carbon credits:

Opportunities to help resolveenvironmental problems 247

13.9.1 Greenhouse effect: causes and consequences 24813.9.2 The “logic” of carbon credits 24913.9.3 Circumstances in which biogas from a sanitary

landfill can be utilized 25113.9.4 Requirements for the implementation of GHG

emission reduction projects in solid waste landfills 25213.9.5 General considerations 253

BIBLIOGRAPHY 255

GLOSSARY OF ACRONYMS 258

GLOSSARY 259

6

PRESENTATION

The role of local authorities fora better environmental policy

The training course on integrated urban solid waste management in municipalities of

Latin America and the Caribbean, held in December 2005 in Rio de Janeiro (Brazil),

represented a significant step in the fruitful collaboration between the Ministry for the

Environment and Territory of Italy and the International Development Research Centre

of Canada (IDRC) through the Environmental Management Secretariat (EMS). This

collaboration had previously resulted in significant benefits through the organization

of a high level meeting held in Sao Paulo (Brazil), which gathered experts, administrators,

professionals and heads of public institutions in order to quantify the process towards

sustainability in the urban solid waste management sector and to assess the situation

through an exchange of information and an evaluation of best practices in each field.

These peak activities, together with some others carried out during the year, pertain

to the Memorandum of Understanding (MoU) signed by the Ministry for Environment

and Territory of Italy and IDRC, which came into force in 2005 and is aimed at achieving

common objectives related to environmental protection and integrating them with social

and economic development. This agreement focuses attention on some specific areas

related to local environmental policy, such as sustainable water and sanitation

management, urban waste management, the promotion of clean technologies and

industrial processes and the use of renewable energy sources, all of which are

processes geared to ensuring local sustainable development.

The MoU established a partnership between the two institutions and implies not only

that both parties are committed to achieving the agreed objectives, but also their

intention to initiate actions at all levels with the participation of developed and

developing countries, international institutions, NGOs and the private sector. The

resulting projects (specifically in Latin America and the Caribbean) will be expressly

devoted to establishing new partnerships (within the broad category of the “type II

initiatives” launched in Johannesburg) in areas of interest common to private and public

sectors, or within each of them, and to supporting local authorities in developing

voluntary processes at the local level.

In this regard, the role that municipalities can play in the sustainability process is of

great importance: the local dimension should be considered as the most significant

for experimenting with new environmental strategies and best practices and demon-

strating their effectiveness on a broader dimension. As stated in chapter 28 of Agenda

21, local authorities construct, operate and maintain economic, social and environ-

mental infrastructure; oversee planning processes; establish local environmental

policies and regulations; and assist in implementing national and sub-national envi-

ronmental policies. As the level of governance is closest to the people, they play a

vital role in educating, mobilizing and responding to the public in the promotion of

sustainable development.

7

Indeed, local authorities can play a more effective role in developing the capacity to

deliver feasible sustainable development outcomes. Policies such as housing, transport,

urban development, waste and water management, have significant impacts on how

cities grow. The traditional framework of policies is not designed to consider

interrelationships between the policies of different sectors; it rather aims to focus on

each policy in an isolated manner: thus, in addition to the improvement of specific

policies, a change in the policy framework itself is required today.

This is particularly true for the urban waste management sector. Waste management

issues are at the centre of environmental concerns in many urban areas, especially

because continued population growth and the expansion of economic activities

stimulate higher consumption of resources and a greater waste generation. In these

circumstances major improvements in efficiency are needed, so as to enable the

decoupling of environmental degradation from population growth and economic

development, and to diminish environmental pressures to sustainable levels. An

effective environmental management of industrial (hazardous) and urban waste can

also serve as a significant mechanism for the creation of new job opportunities, the

promotion of renewable energy sources and the improvement of people’s quality of

life by preventing pollution in urban areas.

The real challenge is to transform waste into reusable resources: measures should be

initiated to stimulate private investment in this field and to create opportunities to

include municipalities as potential beneficiaries of the Kyoto Protocol’s Clean

Development Mechanism for curbing greenhouse gas emissions. For these reasons,

the development of clean technologies – by replacing refuse dumps with final waste

disposal centres – can be included among the advantages of responsible and sustainable

local government policy-making. In more general terms, local governments can play an

important supervisory role, enforce laws and regulations and promote initiatives suitable

for local conditions, including the adoption of specific action plans, awareness raising

campaigns and influencing the market towards the attainment of an environmentally

sound waste cycle.

Paolo Soprano

Ministry for the Environment and Territory – Italy

8

El papel de las autoridades localespara una mejor política ambiental

El curso de capacitación sobre gestión integrada de residuos sólidos urbanos a nivel

de Municipios de América Latina y el Caribe, realizado en diciembre de 2005, en Río de

Janeiro (Brasil), ha sido uno de los pasos más importantes en la fructífera colaboración

entre el Ministerio de Ambiente y Territorio – Italia y el Centro Internacional de Investi-

gaciones para el Desarrollo (IDRC) de Canadá, a través del Secretariado de Manejo del

Medio Ambiente (EMS-SEMA). Anteriormente esta colaboración ya había logrado un im-

portante resultado a través de la organización de una reunión de alto nivel que tuvo

lugar en San Pablo (Brasil), donde expertos, administradores, profesionales y autorida-

des de instituciones públicas se reunieron para cuantificar el proceso en pro de la

sustentabilidad en la gestión integrada de residuos sólidos urbanos, y para evaluar la

situación a través del intercambio de información y evaluación de las mejores prácti-

cas en cada área.

Estas actividades destacadas – combinadas con otras que se desarrollaron en el trans-

curso del año – corresponden al Memorando de Entendimiento firmado conjuntamen-

te por el Ministerio de Ambiente y Territorio – Italia y el IDRC, que entró en vigor en el

año 2005 y apunta al logro de objetivos compartidos relativos a la protección del

medio ambiente y a hacer que los mismos fueran compatibles con el desarrollo social

y económico. Este Acuerdo fija su atención en algunas áreas específicas vinculadas a

las políticas ambientales locales, como por ejemplo en los casos de gestión de resi-

duos sólidos urbanos, gestión sustentable del agua y saneamiento, promoción de tec-

nologías y procesos industriales limpios y uso de fuentes de energía renovable, siendo

todos ellos procesos acometidos para asegurar un desarrollo local sustentable.

El Memorando de Entendimiento, que establece una asociación entre las dos institu-

ciones, implica no sólo que ambas partes están comprometidas con el logro de objeti-

vos acordados, sino que también desean poner en marcha acciones a todo nivel con la

participación de países desarrollados y en desarrollo, instituciones internacionales,

organizaciones no gubernamentales (ONG) y el sector privado. Los proyectos resul-

tantes (en especial en América Latina y el Caribe) estarán expresamente dedicados al

establecimiento de nuevas asociaciones (en la categoría más amplia de “iniciativas tipo

II” que fueran lanzadas en Johannesburgo) en las áreas de interés entre los sectores

público y privado, o dentro de cada uno de ellos, y para apoyar a las autoridades

locales en el desarrollo de procesos voluntarios a nivel local.

En este sentido, el papel que podrían desempeñar los municipios en función del proce-

so de sustentabilidad es de gran importancia: la dimensión local debería ser considera-

da como la más significativa en la experiencia de nuevas estrategias ambientales y

mejores prácticas, mostrando su efectividad en una dimensión más amplia. Tal como

se establece en el capítulo 28 de la Agenda 21, las autoridadeslocales construyen,

PRESENTACIÓN

9

operan y mantienen la infraestructura económica, social y ambiental; supervisan los

procesos de planificación; implantan las políticas y reglamentaciones ambientales loca-

les; y colaboran en la implementación de políticas ambientales nacionales y sub-nacio-

nales. A medida que el nivel de gobernabilidad se acerca más a los pueblos, las

autoridades locales desempeñan un papel crucial en la educación, movilización y res-

puesta al público para promover el desarrollo sustentable.

De hecho, las autoridades locales pueden desempeñar un papel más eficaz en el

desarrollo de la capacidad para producir resultados más efectivos en cuanto al desa-

rrollo sustentable. Políticas públicas como la de vivienda, transporte, desarrollo urba-

no, gestión de desechos y agua, producen un importante impacto en la forma en que

las ciudades crecen. El marco tradicional de las políticas no ha sido diseñado para

tener en cuenta la interrelación entre las políticas sectoriales; más bien intenta

focalizar cada política de manera aislada: es por eso que hoy se requiere un cambio

en el propio encuadre de las políticas públicas, además de la mejora de algunas polí-

ticas específicas.

Esto resulta particularmente cierto en el caso del sector de gestión de desechos urba-

nos. Los problemas en torno al manejo de residuos constituyen la principal preocupa-

ción ambiental en muchas zonas urbanas, en especial porque el constante crecimiento

poblacional y la expansión de las actividades económicas estimulan un mayor consu-

mo de recursos y un incremento en la generación de desechos. En tales circunstan-

cias, se requiere una considerable mejora en la eficiencia para permitir la separación

de la degradación ambiental del incremento de la población y el desarrollo económico,

y para reducir las presiones ambientales a niveles sustentables. La gestión ambiental

efectiva del desecho industrial (peligroso) y urbano también podría ser un mecanismo

importante en la creación de nuevas oportunidades de empleo, en la más amplia difu-

sión de la adopción de fuentes de energía renovable y para mejorar la calidad de vida

de las personas, evitando la contaminación en zonas urbanas.

El verdadero desafío está en transformar los residuos en recursos reutilizables: debe-

rían preverse medidas para estimular la inversión privada en este campo y generar

oportunidades para incluir a los municipios como beneficiarios potenciales del Proto-

colo de Kyoto sobre Mecanismos de Desarrollo Limpio, para abatir las emisiones de

gases con efecto invernadero. Por todas estas razones, el desarrollo de tecnologías

limpias – sustituyendo vertederos por centros para la disposición final de los residuos

– podría incluirse entre las ventajas que se derivarían al contar con políticas responsa-

bles y sustentables en los gobiernos locales. En términos más generales, los gobier-

nos locales pueden desempeñar un papel importante en la supervisión, asegurando el

cumplimiento de la legislación y las reglamentaciones y promoviendo acciones adecua-

das a las condiciones locales, incluyendo la adopción de planes de acción específicos,

sensibilización, y liderando al mercado en la dirección correcta para el logro de un ciclo

de manejo de desechos que resulte ambientalmente saludable.

Paolo Soprano

Ministerio de Ambiente y Territorio – Italia

10

Il ruolo degli enti locali peruna politica ambientale migliore

PRESENTAZIONI

Il corso di formazione sui sistemi integrati di gestione dei rifiuti solidi urbani nei

comuni dell’America Latina e dei Caraibi, tenutosi a dicembre 2005, a Rio de Janeiro

del Brasile, ha rappresentato un significativo passo in avanti a favore della fruttuosa

collaborazione fra il Ministero dell’Ambiente e della Tutela del Territorio – Italia ed il

Centro Internazionale di Ricerca per lo Sviluppo Canadese (IDRC) attraverso il pro-

prio Segretariato per la Gestione Ambientale (EMS). Tale collaborazione aveva già ot-

tenuto un risultato importante attraverso l’organizzazione di un incontro ad alto

livello tenutosi a San Paolo del Brasile, dove un gruppo di esperti, di amministratori, di

professionisti e di dirigenti di istituzioni pubbliche si sono riuniti per quantificare il

processo verso la sostenibilità del settore della gestione dei rifiuti solidi urbani e per

valutare la situazione grazie ad uno scambio di informazioni ed ad un esame delle

migliori pratiche di ogni settore.

Queste attività di spicco – combinate ad altre attività svoltesi durante l’anno – sono

contenute nel memorandum di intenti siglato fra il Ministero dell’Ambiente e della Tute-

la del Territorio – Italia e l’IDRC, entrato in vigore nel 2005, e che ha come scopo

l’ottenimento degli obiettivi comuni per la tutela ambientale e la sua compatibilità con

lo sviluppo economico e sociale. Tale accordo si concentra su settori specifici collega-

ti alla politica ambientale locale come ad esempio: la gestione dei residui urbani, la

gestione sostenibile dell’acqua e dei servizi igienici; la promozione di tecnologie e pro-

cessi industriali puliti e l’utilizzo di risorse energetiche rinnovabili, tutti finalizzati a

garantire lo sviluppo sostenibile locale.

Il memorandum di intenti, che stabilisce una partnership tra le due istituzioni, prevede

non solo l’impegno di entrambe le istituzioni al raggiungimento degli obiettivi concor-

dati, ma anche l’attuazione di attività ad ogni livello con la partecipazione dei paesi

industrializzati e quelli in via di sviluppo, con le organizzazioni internazionali, con le

ONG e con il settore privato. I progetti che ne verranno (in particolare in America Latina

ed i Caraibi), saranno espressamente volti a stabilire una nuova partnership (nella cate-

goria più ampia delle “iniziative di tipo II” lanciata a Johannesburg) nei settori di interes-

se fra il settore privato e quello pubblico, o con ciascuno di loro, e sostenere gli enti

locali nello sviluppare dei processi volontari a livello locale. A questo riguardo, il ruolo

che i comuni possono ricoprire verso il processo di sostenibilità è di estrema impor-

tanza: la dimensione locale va considerata come la più significativa per sperimentare

nuove strategie ambientali e migliori pratiche, dimostrando la loro efficacia su scala più

ampia. Come affermato nel capitolo 28 dell’Agenda 21 “gli enti locali, costruiscono,

operano e mantengono le infrastrutture economiche, sociali ed ambientali,

supervisionano i processi di pianificazione, stabiliscono le politiche e le regolamentazioni

in materia ambientale a livello locale e partecipano all’implementazione delle politiche

nazionali e sub-nazionali in ambito ambientale. Poiché inoltre essi rappresentano il li-

11

vello di governo più vicino ai cittadini, gli enti locali giocano un ruolo vitale rispetto

all’educazione, alla mobilizzazione ed alla responsabilizzazione del pubblico nella pro-

mozione dello sviluppo sostenibile.

Effettivamente gli enti locali possono giocare un ruolo più efficace nello sviluppare la

capacità di trasmettere risultati validi per lo sviluppo sostenibile. Le politiche sugli allog-

gi, sui trasporti, sullo sviluppo urbano, sulla gestione dei rifiuti e dell’acqua hanno un

impatto notevole sulla crescita delle città. Lo schema tradizionale delle politiche non è

atto a considerare l’interdisciplinarità fra le politiche di settore; al contrario si concen-

tra su ogni politica in modo isolato ed è, pertanto, adesso necessario modificare lo

schema di per sé, oltre naturalmente a migliorare le singole politiche. Ciò è particolar-

mente vero per il settore della gestione dei rifiuti. Le questioni relative alla gestione dei

rifiuti sono al centro dell’attenzione ambientale in molte zone urbane in quanto, a

causa della continua crescita demografica e dell’espansione delle attività economiche,

si stimola un maggior consumo delle risorse ed una maggiore produzione di rifiuti. In

queste circostanze è necessario un miglioramento dell’efficienza al fine di scollegare

il degrado ambientale dalla crescita della popolazione e dallo sviluppo economico ed al

fine di ridurre la pressione ambientale a livelli sostenibili. Una gestione dei rifiuti urbani

ed industriali (pericolosi) potrebbe essere anche un meccanismo importante per la

creazione di nuovi posti di lavoro, per diffondere l’adozione di risorse energetiche

rinnovabili e per migliorare la qualità di vita della gente grazie alla prevenzione dell’in-

quinamento nelle zone urbane.

La vera sfida è trasformare i residui in risorse riutilizzabili: vanno presi dei provvedi-

menti per incoraggiare gli investimenti privati in questo settore e per creare le opportu-

nità affinché i comuni vengano inclusi come potenziali destinatari del Meccanismo di

Sviluppo Pulito del Protocollo di Kyoto per la riduzione delle emissioni di gas ad effet-

to serra. Per queste ragioni, lo sviluppo di tecnologie pulite – che sostituiscano l’inter-

ramento con degli impianti per lo smaltimento finale dei rifiuti – può essere inserito fra

i vantaggi delle politiche responsabili e sostenibili dei governi locali. In termini più gene-

rali, i governi locali possono giocare un ruolo importante di regia, garantendo l’applica-

zione delle leggi e delle norme e promuovendo delle attività adatte alla condizioni

locali, includendo l’adozione di piani d’azione specifici; l’aumento della consapevolez-

za e la conduzione del mercato verso la direzione giusta per l’ottenimento di un ciclo

integrato dei rifiuti.

Paolo Soprano

Ministero dell’Ambiente e della Tutela del Territorio – Italia

12

PREFACE

There is a notably growing demand for solutions to urban cleaning issues both in

global bodies and at the level of civil society and local communities. For a long time

these issues have been relegated to the background but diverse governmental and

civil society sectors are now mobilizing to address the problem due to several areas

being affected: disease transmission and therefore public health, water course and

aquifer contamination in the environmental field, social concerns relating to

segregators, in particular children living on rubbish dumps, and pressures deriving

from tourist activities. Another aspect of urban cleaning that has more recently come

to the fore is the issue of the final disposal of solid waste in relation to Clean

Development Mechanisms.

In several situations negative impacts relating to solid waste are fundamentally

associated with inappropriate management. Changing this state of affairs involves not

only a mobilization of resources and improvements in technical knowledge of the

appropriate processes and technologies for each reality, but principally the creation

of instruments that incorporate and structure integrated management models as a

fundamental strategy to achieve a healthy city.

Deep behavioural change is necessary in order to reverse traditional policies and

practices and establish strategies that incorporate the following elements:

! the reduction of consumption, wastage and waste generation by citizens;

! the universalization of urban cleaning services;

! environmentally appropriate treatment and final disposal practices;

! the withdrawal of children from rubbish dumps;

! the potential generation of work and incomes related to waste, promoting the social

and economic inclusion of segregators.

This Manual on Municipal Solid Waste Integrated Management is aimed at contributing

to an improvement in the technical capacities of the public sector, agencies, companies,

NGOs and civil society to deal with aspects of integrated solid waste management in a

sustainable way.

It deals with subjects that are fundamental to the understanding and improvement of

urban cleaning systems and services and covers technical and administrative issues,

questions relating to the preparation, storage and final disposal of waste, as well as

institutional, economic, political, social and legal aspects, including clean development

mechanisms.

Acknowledging that the main responsibility for providing urban cleaning services falls

on the municipal level of government, the Manual provides guidelines that serve as a

reference for decision-makers in the formulation of public policies and corresponding

legislation.

13

The Manual has been prepared by professionals with long-term experience in this

sector who also serve as teachers in the courses offered by IBAM. As part of their

work methodology a preliminary version was examined by participants in the first IBAM

training course, held in December 2005 with representatives from several Latin American

and Caribbean countries, and was subsequently revised and completed. It is intended

for use as a basic didactic instrument that can orientate future workshops.

It is essential that municipal teams in charge of the planning and operation of services

are properly equipped to prepare and implement programs, plans and initiatives geared

to improving urban cleaning systems, including institutional adaptations that are

necessary for the administration of services and the allocation of available resources

in a responsible way, using appropriate technologies and methods and respecting the

particular economic social and cultural circumstances of the local population.

Within this perspective the Manual’s objective is to be a useful tool in integrated

administration training for all those who work with solid waste and to be sufficiently

flexible so that from all the information provided on different forms of “know how”

that which is most useful for application to the particular conditions of each city can

be chosen. You are therefore invited to consider and use the solutions offered by

this Manual.

Tereza Cristina Baratta

Director, National School of Urban Services – IBAM

14

1 The general situation of solid wastemanagement in Latin America andthe Caribbean

1. The general situation of solid waste management in Latin America and the Caribbean

15

1. Based on Diagnosis of Municipal Solid Waste Management in Latin America and the Caribbean, IADB and PAHO, 1997; updatedin the form of “Report on the Regional Evaluation of Municipal Solid Waste Management Services in Latin America and theCaribbean", 2005. (www.paho.org and http://www.bvsde.ops-oms.org/bvsars/fulltext/informeng/informeng.htm).

1.1 Introduction

In the municipal solid waste management sector, an evaluation made during a certain

period has only a relative value as the quality of services can change very quickly.

A well administrated landfill can became a rubbish dump in a few days if a tractor stops

functioning due to some defect that the municipality is not able to quickly repair because

of slow bureaucratic processes involved in buying spare parts or contracting a

maintenance service. Even if the system is in the hands of a private company, through

outsourcing or concession contracts, an interruption in the payment of bills by the

municipality can paralyze services.

However, a periodical analysis of the state of solid waste management services in

several cities of a country can indicate the general trend, which is significant for

answering the question: is waste management improving in Latin American cities?

In practically all Latin American countries urban cleaning services are the responsibility

of municipalities and often a well functioning system in a particular city does not

necessarily reflect the trend in the country as a whole but rather the mayor’s

determination to solve the problem. However, if a study includes a wider range of

cities, a better evaluation can be made of trends both in service quality and the types

of approach to the issue employed by municipal, provincial and national governments

in each country.

The most recent update of the Report on the Regional Evaluation of Municipal Solid

Waste Management Services in Latin America and the Caribbean, which covered the

entire region, was carried out by the Pan American Health Organization (PAHO) in 2005.

As it is the best document produced up to now on this subject, its executive summary

is transcribed here.

1.2 Regional Evaluation of Municipal Solid Waste ManagementServices in Latin America and the Caribbean 1

The Pan American Health Organization (PAHO) in support of Latin American and Caribbean

(LAC) governments, and taking into consideration the significant role performed by

urban sanitation services to reduce health risk factors and environmental impacts,

coordinated the Report on the Regional Evaluation of Municipal Solid Waste Management

Services with the direct participation of public institutions and private agencies, as well

as NGOs involved in solid waste management in countries in the Region.

The Solid Waste Evaluation constitutes a first regional effort in which 36 LAC countries

participated within a common evaluation strategy. The collection of information for

16

Figure 1 – Disordered settlement and informal market close to a rubbish dump

the Evaluation took place in the countries between 2002 and 2003 through a national

coordinating group of representatives from national and local entities involved in solid

waste. The information was obtained through a series of forms that collected basic

demographic, health, education and socioeconomic data from the country and specific

indicators related to urban sanitation services referred to the year 2001. The information

was complemented with an analytical report for the country executed by each country.

The Solid Waste Evaluation proposal emerges from the need to have a frame of

reference that makes the solid waste sector visible in LAC to identify their needs and

possibilities within the comprehensive management concept guided towards improving

the communities’ quality of life. Within this context, the purpose of the Regional

Evaluation is to generate and expand the knowledge of the current situation, which is

critical in many countries, as can be seen by the alarming environmental deterioration

and the sanitary problems related to unsafe solid waste management and the scarce

attention given to this area, mainly to the final disposal of waste with the purpose of

looking for solutions or alternatives at a national and local level to improve the current

situation and be able to accomplish waste management that is truly efficient.

Even though it is true that moderate progress has been made as a result of national

and international initiatives, among which Agenda 21 stands out – agreed upon in 1992

in Rio de Janeiro during the United Nations International Conference on the Environment

and Development – comprehensive solid waste management still represents one of

the most important challenges that national and municipal governments face, as well as

service providers and the community in general. The life styles, the high levels of

consumption, the materials used in industrial production and the introduction of


17

persistent materials in daily human activities, tend to increase the volumes of solid

waste, representing serious problems for its collection, transportation, treatment and

final disposal.

The intensive migration of indigent populations from rural areas to medium and large

cities has created outlying poverty belts, of which the majority lack public service

infrastructure and have completely spread out in a disorderly manner without any urban

planning. In addition, the economic and social impoverishment present in these

settlements, takes many families, mainly women and children, to find in garbage, in the

streets, as well as in final disposal sites, their only means for survival.

The Solid Waste Evaluation estimates that by the year 2001, the LAC population reached

518 million of which 406 million (78.3%) is urban and generates around 369,000 tons of

municipal solid waste daily, of which 56% is generated in large urban centers, 21% in

medium size urban centers and 23% in small urban centers. Approximately half of the

waste generated in LAC is produced by medium and small centers, which tend to have

more difficulty in waste management, the impact to the environment being considerable

since the disposal of these wastes is usually deficient. Just a few of the LAC countries

have comprehensive plans or programs to respond to the sector’s demands. As a

consequence, necessary strategies or components that will allow for the guidance,

regulation and institutional development of the municipalities as sanitation service

providers, as well as the due training of human resources and the capitalization of

financial resources are not proposed.

The Solid Waste Evaluation confirmed the information gaps that exist in the solid waste

area in the countries of the Region. Practically all of them, institutions and organizations

that are involved in this area, manage insufficient information. These gaps are seen

not only at a local level, where they are more evident, but also in institutions at a

national level in charge of defining policies and assigning resources.

Waste collection coverage in the Region varies from 11%-100% with a regional average

of 81%, although with great differences within the countries, more noticeable in medium

and small populations, in which only 69% of the population has collection service.

Adequate sanitary final waste disposal coverage (landfill) for the LAC Region is 23%,

which makes it evident that there is a serious environmental and health problem due

to the proliferation of open air “dumps.” This means that of the 299,000 tons collected

daily in the Region, around 230,000 tons of waste are indiscriminately deposited in the

environment, at best in dumps with an uncertain control. It is presumed that the

remainder, which is not collected, is burned or dumped without any control in vacant

lots, streets, highways and waterways contaminating the environment and endangering

the population’s health. The situation worsens with the lack of adequate hospital and

hazardous waste management, mainly when they are dumped together with municipal

waste, a common practice in several countries in the Region.

The Solid Waste Evaluation shows that average regional generation of residential solid

waste per capita reaches 0.790 kg/inhab/day, with a noticeable fluctuation in countries

18

with a low Human Development Index (HDI). There are cases in which the per capita

generation does not exceed 0.250 kg/inhab/day, yet, in countries where tourism is an

important economic factor, the per capita generation reaches 2.400 kg/inhab/day. With

regards to municipal waste, the per capita generation varies between 0.370 kg/inhab/

day to 2.650 kg/inhab/day with a regional average of 0.910 kg/inhab/day. Likewise,

large cities are the largest generators of municipal waste per capita with close to 1.100

kg/inhab/day while the small and poor settlements in Latin America generate an average

of less than 0.500 kg/inhab/day.

These facts show that economic growth and the level of consumption have a great

influence in solid waste generation, and consequently, demand a more efficient

management of urban sanitation services, mainly regarding sanitary final disposal.

The LAC countries are in different stages of development in the solid waste sector.

At national levels, health and environmental ministries have been evolving to replace

the governing of the sector and the regulation of services to a certain point.

At a local level, municipalities maintain responsibility for services, but with differing

operational modalities: direct public sector administration, outsourcing and the granting

of concessions. The private sector has been becoming ever more prominent, not only

in providing urban cleaning services but also in investment in solid waste sector

development.

Several deficiencies are observed in guiding the sector, and therefore, in its planning

and programming at medium and long term. Municipalities, specifically the smaller ones,

lack management and financial capability, which does not allow for the demands of an

adequate solid waste management.

With regard to the legal aspects applicable to the sector, great gaps can be observed in

the judicial development and in different instruments for their compliance. Even though

there is an abundance of environmental laws, they are scattered in several legal bodies.

This produces an overlapping effect and inconsistencies, which makes it difficult to

implement follow-up mechanisms, control and sanctions. Therefore, the effectiveness

of current legal tools are minimized, even when several countries are developing

specific laws and regulations for municipal, as well as hazardous waste, as is the case

in Bolivia, Ecuador, Mexico and Peru, among others.

The costs for urban sanitation services in the Region fluctuate between US$15 and

US$105 per ton, with an average of US$29 per ton for collected, adequately disposed

of and treated waste. The breakdown of these costs corresponds to sweeping,

collection and urban sanitation in main streets, transfer, treatment and final disposal.


19

The cost breakdown indicates that the highest cost corresponds to sweeping and

waste collection and transportation, representing between 60% and 70% of the

total cost.

Investments in the sector are minimal compared to other public services such as

electricity, potable water and basic wastewater, and concentrate in acquiring equipment

and, lastly, in infrastructure works for final disposal.

In the majority of Latin American countries, financial support for this service is received

through the collection of a municipal rate. This general rate is not exclusively assigned

to the urban sanitation service, but it is part of other services such as public lighting,

real estate taxes and others. The monthly average rates for residential waste in LAC

reaches US$2.5 per user, a value that does not cover the cost for urban sanitation

services, which reflects a deficit of close to half the real cost of those services. In the

English speaking Caribbean countries, urban sanitation services are strongly subsidized

by the central government, through a consolidated fund formed by different

environmental taxes.

The formal segregation and recovery of recyclable materials is not carried out on a

large scale in LAC. On average, the Evaluation showed that only 2.2% of the materials

are recovered from garbage, of which 1.9% is for inorganic recycling and 0.3% to organic

waste recycling, mainly made up of food and garden waste. Informal recycling is widely

promoted in Latin America and its magnitude is difficult to identify due to the fact that

the activities are subtle. Informal segregation has increased in countries that have gone

through a rapid and deep economic crisis as a result of the increase in poverty and

unemployment, coupled by the lack of initiatives to integrate this form of sub-

employment into the solid waste sector.

The inadequate management of solid waste has serious consequences in the

environment and the health of the population, mainly those who are in contact with

wastes. This is the case of the personnel who work in this sector. The majority do not

have the minimum prevention and occupational safety measures. The situation is more

critical for individuals working and living from the recovery of materials from waste,

who work under unsanitary and subhuman conditions, among which there is a significant

number of women and children. Although the direct casualty has not been determined,

several diseases are related to wastes when the conditions conducive to the

development of several disease agents are present.

The direct and indirect environmental and social costs that represent the production,

handling and inadequate disposal of waste to the community are growing and are

significant. The environmental impacts are mainly revealed in the contamination of

surface and underground waters for public supply and the obstruction of drainage

canals due to the uncontrolled dumping of solid wastes in bodies of water.

20

Figure 2 - Environmental degradation caused by a refuse dump

Other important impacts that affect human health are the emission of air contaminants

due to open air burning; the incineration of waste without adequate control equipment;

the transmission of pathogen microorganisms through water; by food; the breeding of

bovine and porcine livestock with contaminated organic waste; as well as vectors that

transmit diseases. These are in addition to aesthetic and nuisance impacts due to noise

and bad odours.

In several countries in LAC, the participation of small companies and private micro

companies in solid waste collection has been increasing more and more, mainly because

this means a more economic alternative for the municipalities and/or sanitation municipal

companies. The advantages of these companies resides in the intensive use of labour

force, the use of very low cost technologies that use animal, human or mechanic

(tricycles) traction and the promotion of greater community participation to facilitate

the material collection and separation operation at the generation source.

The community has a limited participation in solid waste management in LAC.

Community participation occurs mainly when there is support from NGOs and a strong

educational component. Such participation is key to put into practice activities that

take into consideration the principle of the three “R’s,” reduction, reuse and recycling,

and at the same time is supported by a strong national political base that guides the

solid waste sector.

Technological and research development in relation to solid waste is reduced in the

majority of LAC countries. The contribution in research and technological development

from institutes and universities for the solid waste area is scarce. The training of human

resources in the solid waste area is usually carried out in some universities in the

Region as part of the courses related to sanitation engineering and environmental

sciences. This is complemented with a great variety of courses, workshops and seminars

focused on solid waste management.


21

Figure 3 - Correct landfill operation resulting from public administration commitment

Initiatives such as primary environmental care, healthy municipalities and communities,

health-promoting schools and other health promotion strategies are basic to coordinate

initiatives with the capacity to maximize participative management that includes the

community, local government, NGOs and the private sector with the purpose of

establishing healthy policies, create healthy environments, promoting healthy life styles,

personal capacity building through education and empowerment, especially in school

and Ecoclub environments on solid waste management topics. These initiatives offer

great potential for establishing long lasting activities and allowing the use of shared

experiences through community networks and alliances with different institutions that

share a common interest.

The management aspects of the sector, regulations and operation of solid waste

management services, institutional and functional organization, financial self-sustainability

and the participation of the private sector and the community, should be carefully

evaluated in each of the countries to determine the appropriate steps, within the real

possibilities of the countries, to achieve the proposed national and municipal goals.

The solid waste sectoral analysis will continue being a key instrument in this aspect by

providing a comprehensive vision of the sector, therefore, allowing more efficient

approaches and alternatives for their development.

Taking into consideration that solid waste management is a local activity, national and

provincial governments should provide more support to municipalities, especially those

which have scarce managerial capability and limited resources, in which the lack of

information is more significant.

22

2 . For more information consult http://www.un.org/millenniumgoals.

Likewise, international cooperation has a broad field of action, especially in institutional

capacity building and in the identification and support of sectoral investments. The

commitment and will of the governments and financial organizations, and technical

cooperation to guide their efforts towards the achievement of the Millennium

Development Goals 2 open new opportunities to promote and coordinate national and

international activities to improve solid waste management in the Region.

1.3 Solid waste sector trends

The above summary of solid waste management in Latin America and the Caribbean,

based on Solid Waste Evaluation together with other studies and experiences in this

field, makes it possible to identify general sector trends. The issues dealt with below

can present variations between one country and another and between one city and

another depending on the greater or lesser degree of both commitment by mayors

and community participation.

Public awareness of the importance of urban cleaning services andmunicipal solid waste management

In almost all LAC countries there has been an increase in community awareness of the

need for improved solid waste management. The principal causes of this increase are:

! the growing occurrence of environmental problems that affect people’s daily life

and the dissemination of information about them through the media;

! the perceived relationship between solid waste management and the wellbeing and

health of citizens;

! the increasing cost of services, especially where universal coverage is sought in the

urban zones of a municipality, which demands a more professional management by

the municipal administration;

! the widespread exposure in the media of problems in developed countries caused

by defective handling of hazardous industrial waste or its inappropriate final disposal

and the resultant damaging effects on the health of the population.

Circumstantial differences in service provision between small municipalitiesand large or medium-sized cities

A gradual improvement in solid waste management can be found in large cities, not

only in collection services but more so in final disposal. Municipalities with a population

of over 200,000 have more financial resources and capabilities to deal with the

difficulties involved in maintaining sustainable solid waste management.


23

In small urban centres, the category into which most Latin American population centres

fall (in Brazil, for example, 80% of municipalities have less than 30,000 inhabitants),

urban cleaning services are limited to collection, for the most part regular, in zones

where inhabitants can influence public policy (commercial and high income residential

zones) and final disposal takes place in one or more open air dumps without any

sanitary or environmental control.

Larger municipalities generally have a department of urban cleaning, but smaller ones

often only have one person running these services and for essential material resources

depend on departments with other functions.

The importance of political will

Sound solid waste management in Latin American cities depends to a large extent on

the mayor’s commitment to this issue. If the mayor does not consider it to be a priority

sector, budget resources will not be allocated to it, service coverage will not be universal

and service quality will not be satisfactory.

It is evident that with easier access to information and its dissemination through the

internet, those responsible for municipal services have to pay more attention to the

waste issue and are less able to ignore the problem. Only when pressured by society

and environmental control bodies do municipal administrations eventually become more

aware of the problem and begin to allocate more resources to the sector, thus

improving coverage and service quality.

The legal framework

Some large municipalities are establishing norms for solid waste management through

municipal regulations or mayoral decrees and some countries are endeavouring to

develop a national solid waste policy, but these initiatives are sometimes hindered by

political and economic interests that delay their implementation.

Although the legal framework is important, it is not the only requirement for the

achievement of good quality solid waste management. In order for legislation and norms

to translate into an improved solid waste management service a formal commitment by

the mayor to their application is necessary. The training of municipal personnel in the

preparation of tender specifications and contracts is a critical element for an efficient

initiation and operation of contractual relationships with private counterparts, NGOs,

cooperatives, etc.

Carbon credits and the clean development mechanism

The Clean Development Mechanism (CDM) allows developing countries, a classification

into which all Latin American countries fall, to obtain resources through the reduction

of greenhouse gas emissions from their industrial or urban activities.

24

Many mayors regard the timing of the arrival of carbon credits as opportune for providing

financial support for municipal endeavours to improve solid waste management services.

The resources obtained from the sale of Emission Reduction Certificates (ERC) will

not guarantee the operation of urban cleaning services, but with the dissemination of

information on how this mechanism functions, municipal administrations will know how

to maximize its economic advantages to fulfil municipal needs. Nevertheless it must be

remembered that such benefits from the Kyoto Protocol Clean Development Mechanism

are in effect only up to 2012.

Composting

Composting is a procedure that is increasingly applied in developed countries due to

the prohibition of organic matter dumping in landfills, and is now reappearing in

developing countries. This system, which can be operated manually in small towns or

be mechanized where large amounts of waste have to be processed, offers the great

advantage of reducing the generation of leachate instead of producing biogas in landfills,

and in addition prolongs the latter’s useful life.

A complementary advantage of a composting system is that it can contribute to the

viability of establishing and operating a medium or large size plant by generating income

through the sale of Emission Reduction Certificates. This is so because there is an

already existing methodology, tested by the Intergovernmental Panel on Climate Change

(IPCC), that has determined that composting does not merely reduce but avoids the

emission of greenhouse gases as organic matter in aerobic decomposition only gives

off carbonic gas and water and not methane, which is the harmful gas that would be

generated in a landfill if the organic matter was deposited there.

Difficulties involved in the establishment of new landfills

PAHO’s diagnosis confirms that one of the weak points of solid waste management

systems in Latin American cities is final waste disposal. As mayors become increasingly

aware of the seriousness of this problem, refuse dumps are beginning to be closed or

converted.

In such cases the municipality must decide whether to establish a landfill in the same

place, where people are already accustomed to refuse disposal, or to begin one from

scratch in another place. The latter option has presented such serious problems that

the construction of several new landfills has had to be suspended in response to the

reaction of the local community, not to mention the difficulties involved in obtaining

environmental licenses for new sites.

Municipal administrations or contracted companies offer compensation to local residents

but this is not always accepted. In many cases these problems result in municipalities

continuing to operate rubbish dumps and abandoning the establishment of new

installations for the final disposal of waste collected in the city.


25

Communities have also reacted negatively to the establishment of new transfer stations

on the grounds that in general landfills and other urban cleaning installations are poorly

managed. It is necessary to convince local residents that a well managed landfill can

exist relatively close to houses. This is a long process and satisfactory results will

depend on the provision of numerous examples until residents become convinced

that it is possible.

Informal segregators and formal selective collection systems

Due to the growing unemployment that is found in almost all Latin American cities,

especially the larger ones, more and more people resort to the streets in search of

some means of survival. The last hope is recyclable waste that can be found amongst

the refuse.

On the one hand this activity has positive aspects: waste can be a source of income

for these people who do not have any other way of surviving and their work removes

a significant amount of material from the urban cleaning circuit, and therefore reduces

the costs of collection, transfer and final disposal, as well as extending the useful life

of landfills. On the other hand, the segregation of materials is often done in a disorderly

way, with bags of domestic waste being opened, materials that can be commercialized

separated and the waste that the segregator is not interested in is left scattered on

the street, which produces serious problems and much more work for the sweeping

services.

In addition municipalities that are implementing formal selective collection systems are

facing difficulties in that before the truck passes to collect the recyclable waste, the

street segregators have already taken it.

Even where the recycling system is institutionalized with the participation of segregator

organizations, other independent segregators compete in the streets with the formal

system. This phenomenon is happening in almost all large and medium-sized cities in

Latin America and the prognosis is that it will increase.

In many South American cities segregators working in rubbish dumps or landfills react

forcefully when the municipality attempts to implement the closure of the site and

begins a new landfill where their activity will not be allowed. This resistance on the part

of segregators is due to the danger of them losing their only source of income, while

the public authority is not able to create hundreds of jobs overnight or provide programs

that generate income to replace that gained from segregation activity in landfills and

the streets. This situation will continue while unemployment remains one of the principal

scourges of Latin American countries.

26

Contract types

Municipal administrations face two big challenges in relation to solid waste management

in Latin American cities: to provide a universal service and to improve its quality.

As municipal budgets are finite, mayors are beginning to look for more effective and

less expensive service provision models and are increasingly contracting work. As a

result, most large and medium-sized cities outsource collection, transfer and final

disposal operations thus transferring to the private sector the burden of investment

and operational costs.

The municipality for its part takes on the monthly payment of bills for services rendered

and the coordination and supervision of such services. In recent times some large

cities have contracted services with long term concessions, especially for the

establishment and operation of large sanitary landfills that require significant investment

and therefore a longer period to see a return on it. In general this has proved to be a

satisfactory solution, provided that the specifications are reasonable and the tender

process respects the limits required by law and administrative probity.

Economic sustainability of the sector

In general, a municipality’s income from rates or specific tariffs is nowhere near enough

to cover the costs of urban cleaning services. The incidence of payment arrears is high

and there is not much that can be done to reduce it as an interruption of collection

services would only reduce the cleanliness of the city as households that do not

receive this service would find another, no doubt inappropriate, way of disposing of

their rubbish.

This constitutes one of the main impediments to good quality service management as

municipal administrations have to allocate monies from their budgets for urban cleaning

services without a corresponding income from rate or tariff collection, a state of affairs

that is detrimental to other municipal services.

Money raised together with national governmental or multilateral bodies for investment

in equipment such as collection trucks or in the construction of installations such as

landfills, usually does not solve this problem. The resources needed for the maintenance

of sound and sustainable urban cleaning operations have to be allocated from the

municipal budget and this represents the biggest challenge faced by administrators,

but success is dependent on the mayor’s level of commitment and political will to

prioritize the issue.

The trends of change

Many municipalities are training their technical personnel and seeking resources from

provincial or national bodies with a view to improving service quality. This is due not


27

only to the increased awareness of both mayors and the general public about the

significance of this issue, but also to the improved performance of environmental

control bodies and national ministries that oversee municipalities’ compliance with their

legal obligations. As a result, municipal administrations are signing agreements that

establish periods within which service provision has to reach specified levels of quality

and coverage. There is now an unprecedented level of attention and debate on municipal

solid waste management and a seemingly inexorable search by municipalities for models

that are sustainable from both a socioeconomic and environmental perspective, with

the help, even if sporadic, of provincial and national governments.

28

2 Integrated solid waste management

2. Integrated solid waste management

29

Latin American and Caribbean cities present great regional and local imbalances, which

call for the establishment of new concepts, frameworks and practices in regard to

solid waste management. Typical situations are:

! high technology industrial processes aimed at competitive insertion in global markets

side by side with obsolete industrial processes that produce significant

environmental damage;

! consumption pockets having a pattern associated with high levels of refuse

production equivalent to that of developed countries together with large sectors

of the population who do not have access to consumer goods;

! the availability of waste processing technologies together with a lack of the financial

and human resources necessary to maintain them and the presence of large groups

of segregators in streets and rubbish dumps.

Traditional practices, generally insulated, address the problems of solid waste in a partial

way, dealing only with the management of the system, treatment plants and final

disposal. It is of fundamental importance to also take into consideration the generation

of waste, the sustainability of systems and the role of citizens as generators,

consumers, recyclers and managers, in order to establish a shared concept in which all

win and positive socio-environmental outcomes are produced.

The concept of integrated solid waste management considers the entire cycle including

production, consumption, discarding and final disposal. In practice this concept ranges

from the minimization of waste generation in the production process, including

packaging, to the maximization of its reuse through the implementation of more

appropriate collection systems for each situation and the employment of treatment,

recovery and recycling processes and technologies. In this way only waste with no

utility is left for final disposal.

It is important to emphasize the significant differences between traditional and

integrated approaches to this subject: in the latter waste is always regarded as a

raw material for the production of new products through reuse, recycling or

recovery. Waste therefore has a commercial value that can be added to the

production chain thus creating new work opportunities and generating income for

various sectors of society.

The optimization of these circuits reduces to a minimum the amount of waste for

final disposal. The reduction of waste to be collected, transported and disposed

of in landfills – which as a consequence will occupy smaller areas or will have a

longer useful life – contributes to the economic and environmental sustainability

of systems.

This is the approach recommended by Agenda 21: the transformation of the production

and consumption matrix on the basis of the 3R’s – reduce, reuse and recycle – to which

has now been added a new R for recover, as a result of which they are now called the

30

“Environmentally sound waste management must go beyond the meresafe disposal or recovery of generated waste and seek to address the

root cause of the problem by attempting to change unsustainablepatterns of production and consumption. This implies the application

of the integrated life cycle management concept, which presents aunique opportunity to reconcile development with environmental

protection.” (Agenda 21, chapter 21)

4R’s. This model has been used as a tool to solve problems arising from the increasing

amounts of solid waste generated by the industrial society.

Putting these criteria and the concept of integrated solid waste management into practice

in Latin American and Caribbean cities requires the development of local participation

processes.

Participation processes allow the different stakeholders to identify opportunities that

can lead to solutions for the problems presented by solid waste, through the

development of an Integrated Solid Waste Management Plan (ISWMP).

Usually it is recommended that these plans are developed at a municipal or local level.

However it is possible for a group of municipalities to develop them and share some

solutions especially for the final disposal of waste. Plans can also be formulated at a

regional, provincial, or in the case of smaller countries, even national level. On whatever

scale they are made, ISWMPs must be complemented by national and regional policies

on this issue.

Some elements are essential for the development of integrated solid waste management

(ISWM) processes:

! the participation of all public, private and community stakeholders in the conception

and planning of processes and solutions, and in the implementation of an urban

cleaning system;

! the integration of all elements of the solid waste cycle in the 4R’s processes;

! the integration of technical, environmental, social, juridical, institutional and political

aspects in order to guarantee system sustainability;

! the articulation of proposed solid waste systems with overall urban planning and

other urban systems, particularly environmental sanitation, including water provision,

sewerage systems, rainwater drainage and vector control.

Integrated management depends on the functioning of specific sub-systems that involve

installations, machines, labour and technology, not only provided by the municipality

but also by other agents participating in the management, amongst which are:

! citizens themselves, responsible for the separation and differentiated pre-collection

storage of recyclable materials and other domestic waste;

2. Integrated solid waste management

31

! large generators, responsible for their own waste;

! segregators organized in cooperatives, responsible for separating recyclable materials

discarded by citizens and selling them to the relevant companies;

! health institutions with an internal management of infectious waste that either

sterilizes it or appropriately separates it by type for differentiated collection;

! the municipality, that through its agents, institutions and contracted companies, and

by means of contracts, agreements and cooperation accords, plays the principal

role in the integrated management of the entire system.

In addition to the technical and financial aspects of conventional urban cleaning systems

and final disposal systems, integrated solid waste management prioritizes the social,

environmental and political-institutional dimensions and system sustainability. In order

to guarantee sustainability from a multi-disciplinary and trans-disciplinary perspective,

specific approaches must be promoted in each related field:

Social – community participation and quality control; environmental information

dissemination and education as instruments for the transformation of personal and

collective production and consumption patterns; and the social inclusion of segregators

who have to be organized, valued and associated in the solid waste production chain,

thus generating income and jobs.

Environmental – the development of clean technology for application to solid waste;

a rational use of natural resources taking into account waste minimization; reusable

material recovery; and appropriate treatment and final disposal.

Economic-financial – an analysis of system costs and the possibility of minimizing them

in order to make systems economically viable; the recovery of operational costs through

differentiated charge mechanisms according to generator profile and payment capacity.

Political-institutional – the integration of public authorities and other stakeholders

and institutions with a clear delimitation of responsibilities; the formulation of specific

policies for solid waste management; the implementation of juridical instruments and

ISWMPs, including the possibility of consortium solutions.

Technical-operational – the establishment of a specific department and the

appointment of responsible personnel; the definition of training programs; the

determination of the appropriate technology for each situation; the provision of

sufficient capacity in machines and labour to provide universal coverage in public urban

cleaning services, irrespective of the socioeconomic level and ethnic origin of the

population.

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3 Institutional models and paymentfor services

3. Institutional models and payment for services

33

3.1 Concept

A city’s urban cleaning system should be institutionalized on the basis of an integrated

management model that, to the maximum degree possible, has the capacity to:

! foster the economical sustentability of operations;

! protect the environment;

! protect inhabitants’ quality of life;

! contribute to the solution of socioeconomic problems related with the issue.

The municipal solid waste management model not only has to allow for the participation

of the community but also specifically facilitate it in order to generate public awareness

of the different activities involved in the system and its implementation costs, and

induce an acknowledgment by citizens of their role as consumers and therefore as

generators of solid waste.

Such participation would directly result in a reduction of solid waste generation, cleaner

streets, the appropriate preparation and storage of waste for collection and

consequently a cheaper operation.

It is important that citizens know that they are the ones who are paying for the system

through taxes, rates or tariffs. In summary, community participation is a key element in

the sustainability of the system while the municipality is responsible for establishing

an integrated management that necessarily includes awareness raising programs for

citizens who will then perceive that the political will to prioritize municipal solid waste

management exists.

This priority must be considered in the definition of municipal fiscal policy, which has

to be technically and socially just, and in the subsequent budget allocation to the

system that should include provision for environmental education and the development

of programs that generate income opportunities and employment.

Policy making is based on the participation of social leaders, private companies, and

public institutions active in the city and having significant environmental responsibilities.

Policy instrumentation will be structured through the approval of urban cleaning

regulations whereby the city legitimizes the adopted management model and social

obligations, and defines infractions and their respective fines. Such regulations must

clearly reflect the objectives of the public authority and raise public awareness in

regard to appropriate urban solid waste management and environmental problems.

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A public service is an activity undertaken by a public body with a viewto satisfying a public interest need.

What characterizes a public service, and distinguishes it from othereconomic activities, is that it is essential for the community and

therefore its provision represents an obligation for the publicauthority and its management is subject to the legal principles

specifically related with the efficient provision of service to thecommunity.

Public services are all material activities assigned by law to the Statefor it to exercise, directly or through delegates with the objective of

effectively satisfying collective needs, under a partially or totallypublic regime.

3.2 Forms of administration

In general the municipality is, directly or indirectly, responsible for organizing and

providing essential local services and is therefore responsible for urban cleaning

services.

Urban cleaning systems can be administered in different ways:

Direct municipal management

In this case the provision of urban cleaning services is the responsibility of a municipal

department or body.

This model is generally used in smaller cities that do not have a volume of service

provision that is attractive to the private sector.

Except where they have been resolved in particular cases, the chronic problems inherent

to this model are: insufficient budget, inevitable bureaucracy, low degree of training,

political interference and frequent crises in the service. The negative results of this

group of difficulties are: a dissatisfied public, sanitary and environmental problems,

and indeterminate service costs.

Autonomous authority

This modality involves the creation of a public company specifically for the administration

of urban cleaning.

This model is more flexible than direct municipal administration and is more compatible

with the dynamic of daily urban cleaning tasks. It also facilitates greater management

autonomy, the creation of a specialized labour force and better conditions for budgetary

planning.


35

3. Integrated Solid Waste Management Workshop organized by IDRC in Sao Paulo, Brazil, 2005.

Positive examples of urban cleaning administration by municipal public companies

can be found in some cities in Ecuador, Colombia and Costa Rica with populations of

no more than 500,000. In these cases the companies have several responsibilities

including planning, supervision and the charging of tariffs for services provided. In

addition, they have the necessary flexibility to adopt appropriate alternatives for the

provision of some components of the service, including sweeping, treatment, final

disposal and the recovery of energy from waste by generating biogas and in some

cases selling carbon credits 3.

This model is only appropriate for large cities as it requires the creation, organization

and equipping of a new specialized structure in the municipality.

Outsourcing

In this model a private sector company is contracted to undertake an activity, with a

predefined mechanism of payment based on the specific services to be provided and

technical-administrative convenience. Outsourcing is based on the concept of public

administration undertaking the functions of planning, coordination and overseeing while

the private company is responsible for operations.

It should be emphasized that service outsourcing can be employed on different scales,

from contracting well structured companies, specialized in certain types of operation

such as landfill management, to contracting micro-companies or independent workers

who undertake waste collection with carts pulled by animals or the manual operation

of small-sized landfills, for example.

Outsourcing, if well planned at every stage – from specifications in the bidding phase

to the overseeing of operations – can make a large contribution to the municipal

administration’s ability to improve the quality of services provided to the public, especially

in regard to the speed of response to operational requirements (for example the

purchase of spare parts for collector vehicles).

In many LAC cities outsourcing is employed for urban cleaning services with sweeping

and/or collection often undertaken by small civil society organizations. Some functions

are undertaken by NGOs, workers cooperatives or small companies through contracts

established by municipalities. All these cases of delegating state functions to civil society

authenticate outsourcing as an efficient practice.

Concessions

In this modality the concession holder plans, organizes, implements and coordinates

the service, and can even outsource operations and collect payments directly from

users/beneficiaries of the service.

36

This management model is adopted in special situations where the public authority

does not have the necessary technological or budgetary resources to implement

interventions or finance the significant investments that are indispensable in dealing

with problems related to municipal solid waste management in general or a particular

aspect of it.

In general, concession contracts are long term to allow for a return on investments in

the system through tariffs charged to users. However, significant difficulties lie in the

limited guarantees that concession holders receive in regard to the collection of payment

for their services and the problems that municipalities have in preparing tender

specifications, calculating costs and overseeing services.

This type of modality has proved ineffective for collection services, but has been

widely employed with relative successs in landfill management, although it functions

less well when applied in small cities.

Free market

This model can be applied for example to large-scale solid waste generators when

municipal regulations have defined the maximum quantities permitted for collection by

the common domestic collection system and have established that large-scale generators

have an obligation to contract, at their own expense, authorized companies for the

collection of excess waste.

It can also be applied to the collection of construction rubble and other civil construction

waste in order to alleviate the burden on the public system.

Consortium

A consortium results from an agreement between municipalities with the objective of

achieving established common goals. All of each municipality’s human and financial

resources available for a certain initiative, program or project are combined in a

consortium to facilitate its implementation.

Any of these alternatives, or any combination of them, has to be selected on the basis

of both low cost and environmentally sound technique and with a view to establishing

a self-sustainable system that is resistant to changes of administration.

In the case of public services that are delegated to third-parties through concessions,

the issuing authority keeps the ownership of the service and the right to oversee it,

which implies a need for technical and administrative training in order to undertake the

activities pertaining to the process, including technical decisions, definition of reference

framework, formulation of tender specifications and contracts, and the overseeing

and control of service provision.


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Administration Description

Direct municipal management Urban cleaning activities run by a municipaldepartment or body.

Table 1

Forms of urban cleaning service administration

Autonomous authority Urban cleaning administration by a public companyspecifically created for that purpose.

Outsourcing The contracting of a private company to undertakecertain activities.

ConcessionEmployed when the public authority lacks sufficientresources to finance the necessary investment inthe system.

Free market

Applied in the cases of large-scale generatorswhere regulations define maximum limits formunicipal collection, leaving the generatorresponsible for contracting a collection companyat their own expense.

ConsortiumAn association of municipalities for commonmeasures and projects, especially in solid wastefinal disposal.

A city’s urban, demographic and economic characteristics as well as the socio-cultural

particularities of its inhabitants must be considered in defining the form of

administration, while at the same time taking into account the following factors:

! cost of service administration, management and supervision;

! autonomy and flexibility in planning and decision-making;

! autonomy in the application and reallocation of budgetary resources;

! investment capacity for technological development, IT systems and quality control;

! investment capacity for human resources and the generation of income and

employment;

! responsiveness to social and political demands;

! responsiveness to changing economic circumstances;

! responsiveness to operational emergencies;

! responsiveness to growth in demand for services.

As has already been said, direct administration of the entire urban cleaning system

is common in small cities. In such cases management is usually undertaken by a

municipal body or department that shares resources with other sectors of public

administration.

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In determining the form of urban cleaning services administration intourist cities seasonal fluctuations in demand for services has to be

particularly taken into consideration.

Whatever model is adopted, activities should always be regulated bythe public authority.

This type of administration that shares resources with other bodies of the municipality

usually has a relatively low cost in comparison with a body or institution exclusively

devoted to urban cleaning management. However, the other factors listed above are

difficult to achieve and the service tends to have a lower priority than other services

sharing the same resources and having a greater potential for political visibility.

In cases where refuse collection and street cleaning services are outsourced by

contracting specialized companies, the municipality only undertakes the administration

of contracts and the monitoring of service quality and therefore the municipal

administrative nucleus can be small.

For their part, the companies charge the municipality enough to cover both operational

costs and capital expenditure, liberating the municipality of the need to invest resources

in the purchase of machines and equipment.

In such a model there can be problems when unforeseen eventualities arise, such as

ones relating to social and political demands, changing economic circumstances and

operational emergencies, as the predetermined form of remuneration established in

the contract may not cover them. It is therefore advisable that the municipality establishes

contract devices or alternative plans to deal with such eventualities.

A model that is worth highlighting is the one employed by the Rio de Janeiro City Urban

Cleaning Company (COMLURB), in the context of large Brazilian cities, and by the Public

Cleaning Companies of Cuenca, Ecuador, and Pereira, Colombia, in the context of

medium-sized cities in the Andean region. All of them are autonomous urban cleaning

companies and are therefore able to define their own budget allocations, establish

human resource policy and most importantly, determine plans, strategies and the logistics

of their operations. They can also outsource operational, management and

administrative services, and define the technical terms of contracts. These companies

can develop or subsidize research and technologies related to urban cleaning in general

as well as specific areas of it. The existence of such agencies exclusively devoted to

urban cleaning demonstrates the commitment of the municipality to keeping the city

clean and caring for the urban environment.


39

The term “tariff” refers to the price charged for a public serviceprovided in an optional form, that is to say that the tariff is

proportional to the amount and quality of the service used, whichmust be well defined and specifically calculated.

The term “rate” on the other hand, refers to a tax on the availability ofa public service provided by the public authority, whether the tax-payer uses it or not. The value of the rate must reflect divisibility

amongst tax-payers in accordance with potential usage by each one.

In all cases, and whatever the administration modality, direct or autonomous, the

municipality has to harmoniously combine two elements:

! just and sufficient payment for services;

! ensured collection of charges for urban cleaning.

3. 3 Payment for services

The singularities of tax legislation in each Latin American and Caribbean country makes

it difficult to compile a complete generalized summary of the issue of payment for

urban cleaning services.

This chapter therefore concentrates on a basic outline of the subject, which in some

cases may need to be adapted to the particularities of each country’s legislation.

In regard to the collection of payments for service provision, an urban cleaning system

can simply be divided into three components: domestic waste collection, street cleaning

and final disposal. In the case of domestic waste collection, for example, the Municipality

can charge residents a specific rate, usually called “Waste Collection Rate (WCR)”. In

cases of concession, the company responsible for providing such services may also

be responsible for collecting payments for them. Certain specific services where usage

can be measured and users are clearly identifiable can be priced and therefore be

charged for exclusively through a tariff.

Urban cleaning systems are financed by almost all of the population but not in a direct

way. Financial resources raised by the waste collection rate cannot be allocated

exclusively to the system due to municipal tax regulations. Similarly, a municipality cannot

charge residents of a street for the sweeping and cleaning services of that street in

particular as it is an indivisible service. It is therefore necessary that municipal policy

ensures a sufficiently large budget allocation to cover the cost of the system and

essential investment in it.

40

In some Latin American cities there is an incipient trend towards payment through

tariffs, i.e. where payment levels are related to the volume of waste generated. This is

being applied to particular geographical areas and follows the “pay as you throw”

principle.

There are few legal remedies for the problem of non payment, or delayed payment, of

rates or tariffs. Waste collection is not a service that can be suspended when bills are

not paid, as electricity or drinking water provision can be, because rubbish put in the

street by the non-payer has to be collected anyway for public health reasons.

In the absence of other available strategies, and even though it is a legally dubious

measure, in some cases an authority may resort to inscribing the property of the non-

payer in the municipal register of public debt. However this measure does not have

much punitive value as it represents only a long term threat to the non-payer in the

form of the eventual confiscation of his or her property.

There is no consensus about the most appropriate basis on which a municipal rate for

financing urban cleaning services should be calculated. There have been attempts to

relate the determination of this rate to the consumption of drinking water or electricity,

or to the frontage width of the plot, etc. In some countries only a reform of the tax

system would provide municipalities with the necessary instruments to reimburse them

in a socially just way for the urban cleaning services that they provide to citizens.

Once these issues are resolved, it has to be taken into account that financial resources

raised by cleaning and solid waste management rates become part of the Municipal

Treasury. There are no guarantees that they will be used in the urban cleaning sector,

this being dependent on the political will of the administration or public budget control

mechanisms. It should also be noted that the updating or correction of the rate depends

on authorization by the municipal council, which in general is not inclined to increase

the tax burden imposed on citizens, especially so in view of the socioeconomic

conditions of most Latin American and Caribbean populations.

It is therefore necessary to reverse the tendency to attribute a low priority to urban

cleaning services that results in them receiving fewer resources than are necessary. If

it is not possible to adequately finance the system, the quality of services deteriorates

and a vicious circle is established. The municipal solid waste management will be defective

due to insufficient resources and the population may not accept the payment of rates

because it is not receiving good quality service.

The municipality then has to choose one of the following options:

! to face for a certain period the political cost involved in increasing taxes, if this is

necessary, until the situation balances itself with an improvement in the quality of

services provided;


41

Payments should cover the costs of the system which includeexpenditure on labour, transport, maintenance, replacement ofvehicles and other equipment; backup, supervision and support

services; capital expenditure, research, technological developmentand administration.

! to subsidize the cost of the service during an initial period until service quality

reaches an adequate level, at which point the subsidy can be gradually reduced

as its value is gradually incorporated in the rate specifically charged to finance

the service.

In regard to investment, both for the purchase of equipment and the installation of

treatment and final disposal units, municipalities almost invariably need to resort to

sources of finance that do not always offer appropriate terms and involve prerequisites

that are not easy to adapt to.

A feasible solution for municipalities that do not have resources for investment is, as

has already been mentioned, outsourcing through contracts with private companies

that, with their own resources (labour and machinery), undertake collection, street

cleaning, treatment and final disposal services.

In such cases a concession can also be an appropriate alternative especially when the

necessary investment is higher and requires a more prolonged period to allow for a

return on it. Here a tariff is determined as the means by which the concession company

makes a return on its investment.

It is worth digressing to mention industrial waste management. In this case, a sustainable

balance must be established between generators and the private operators of centres

for treatment and final disposal. The investment needed for these units is very high

and the acquisition of licenses from environmental control bodies involves a long and

complicated process. However, when an industry is producing a certain product the

cost of an appropriate final disposal of waste generated in the production process

should be reflected in the sale price of that product.

Payment for urban cleaning systems is calculated by applying the following basic

equation:

Payments = Expenses

Expenses = Municipal Treasury resources + amount collected from WCR

+ amount collected from tariffs and various other incomes

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The charging of a realistic and socially just rate that citizens canafford and that effectively covers the cost of services and applies the“he who can pays more” principle implies political measures that are

dependant on the will and determination of the mayor.

Irrespective of the management model adopted, Municipal Treasury resources plus the

money from tariffs should be equivalent to the budget for expenditure and capital

costs for all the operations involved in the cleaning of a city.

The payment for waste collection services to large generators (restaurants, hotels,

supermarkets, etc.) as well as for other services to which a tariff can be applied (i.e.

that can be measured) such as special collections, medical waste collection and the

removal of construction rubble or discarded items, can be charged by collecting

companies authorized by the municipality.

It should be emphasized that all operations not financed by adequate tariffs and an

efficient tax collection system, will have to be sustained by resources from the Municipal

Treasury, in which case the budget must allow for a specific allocation to the urban

cleaning sector, otherwise the Municipality would have to reallocate resources designated

for other areas.

It should be noted that an efficient way of reducing urban cleaning costs is to motivate

the population to decrease the amount of waste generated and implement specific

programs for the segregation of recyclable waste at source and its selective collection,

or create waste recycling subsidies.

3.3.1 Guidelines for the calculation of a waste collection rate

For the system to be economically sustainable, the basic unit of the waste collection

rate (WCR) should be the quotient of the total budget for domestic solid waste collection

services and the number of households in the city.

The establishment of reliable administration and supervision mechanisms for all services

relating to urban cleaning is essential in order to correctly ascertain the real costs

involved in service provision and therefore the appropriate base for calculating the

amount of finance needed to operate the system in an efficient and sustainable way.

The basic WCR value can be adapted to the particularities of individual neighbourhoods

in the city, taking into consideration factors such as social stratum (with a view to

socially just pricing) and operational characteristics.


43

Social stratum is determined on the basis of the average purchasing power of the

inhabitants of different zones of the city. In general a distributive criterion is applied,

so that higher income sectors subsidize services provided to the less well off.

Operational characteristics reflect the amount of labour and materials used in the

collection process depending on property usage (commercial, residential, etc.), location,

demographic density, topographic conditions, type of road surface, etc.

In recent years a more conservationist vision is increasingly influential in the

determination of pricing polices for urban cleaning. This approach involves a greater

community commitment to segregating waste at source (home, shop, market, etc.) in

order to facilitate collection, handling and particularly recycling. The promotion of this

model is important but depends on a wide motivational and educational campaign in

the community. The establishment of a charging mechanism based on the amount of

rubbish generated, so that those who generate more rubbish pay more, produces an

economic benefit for the population as a whole.

The budget also has to cover the costs of transfer, transport, treatment and final

disposal, as well as costs relating to administration, management, monitoring systems,

capital expenditure, education and technological development that are linked to

collection.

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4 Legislation and environmental licenses

4. Legislation and environmental licenses

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4.1 Introduction

Integrated municipal urban cleaning system management is based on the fundamental

conceptual premise of community participation and a systematic political exercise

involving all institutions linked to the pertinent spheres of government.

The community participates in this management in two ways:

! contributing to the financing of services and monitoring them;

! cooperating with cleaning by reducing the amount of waste; reusing, segregating,

classifying and recycling materials; appropriately preparing and storing waste for

collection, and by not throwing rubbish in the streets.

Community cooperation should be considered as the principal agent for transforming

the efficiency of services and consequently generating beneficial operational and

budgetary results.

Citizens can be encouraged to reduce the amount of waste that they produce in order

to diminish the costs of the operation. This approach could be called the principle of

service reliability and citizen cooperation for integrated solid waste management.

A combination of citizen cooperation and measures to increase the reliability of urban

cleaning services constitutes a powerful pairing that can solve the principal problems

relating to urban cleaning systems. Measures geared to guaranteeing good quality

operations and a well structured program of environmental education need legal

instruments that support them.

4.2 Legislation

The legislation required to set up an urban cleaning system falls into three general

categories:

! the first, of a political and economic order, establishes the legal forms for

institutionalizing the administration of a system and the methods of payment and

charging for services;

! the second, establishes operational codes, orientates, regulates and determines

procedures and the obligations of tax-payers and urban cleaning agents, and defines

administrative processes and punitive measures;

! the third is the legal structure that regulates general environmental issues on a

national basis and in particular deals with licenses for the implementation of activities

that represent a risk to public health or the environment.

In Latin American and Caribbean countries there is wide ranging legislation in the form of

laws, decrees, ordinances, rulings and regulations that manifest an increasing concern

46

for environmental protection. In regard to urban cleaning initiatives mostly emanate from

municipal councils under their organic law and through local legal instruments.

For example, the Brazilian Federal Constitution determines that a municipality constitutes

a political entity, as prescribed by the 1st and 18th articles, which establish that the

Brazilian Federation comprises the Union, the states and the municipalities. Municipalities

can legislate, provide services, establish and collect municipal taxes and choose their

mayors and councillors.

As established by article 23, sub-sections VI and VII, municipalities are also responsible

for the protection of the environment, combating contamination and preserving forests,

fauna and flora. Article 30 sub-section I allows them to legislate for local matters in the

public interest and therefore to implement municipal environmental policy. Sub-section

II of the same article, authorizes them to supplement federal and state legislation where

appropriate, and sub-section VIII grants them exclusive authority to legislate on land

planning and land usage in their territory.

Article 225 of the Federal Constitution imposes on public authorities (Union, State and

Municipal) and the community a duty to defend and preserve the environment for

present and future generations thus establishing that a municipality has an obligation

of environmental protection. The municipality can therefore pass environmental

protection legislation and enforce it.

In most Latin American and Caribbean countries, a municipality can, under its organic

law, regulate the granting of licenses by the relevant municipal body for the exploitation

of water and mineral resources, and introduce other public authority instruments aimed

at protecting the environment, including the making of agreements to improve

environmental management.

Furthermore, when the governing plan for a city is formulated, in the section on

environmental policy an environmental management system can be established through

which environmental policy is implemented (Municipal Council for the Environment,

Environment Conservation Fund and Municipal Environment Department).

The environmental management system will include amongst its functions, the design

of environmental protection projects, either directly or through agreements; the

implementation of environmental impact assessment processes; the analysis of projects,

works or activities that actually or potentially produce environmental degradation; and

the requiring where necessary of environmental impact studies or environmental

recuperation guarantees prior to the granting of a license.

Taking into account the urban scale (determined by the number of inhabitants) and the

city’s socioeconomic and cultural circumstances, under their organic law municipalities

must decide on the best alternative for the institutionalization of the urban cleaning

system, the form of management, the charging of rates and tariffs and associations

with other bodies that can contribute or cooperate, irrespective of their institutional

status in the country.

Specifically, municipal urban cleaning regulations should serve as the spine of the city’s

urban cleaning system by establishing the essential principles that govern the conduct

of both municipal authority and citizens.


47

In recent times an innovative vision, known as ecosystem management, has come to

the fore in environmental assessment: the incorporation of the river basin concept in

the definition of the area of influence or impact of a project, which requires legal

instruments to cover the extrapolation of municipal responsibilities. This concept is

particularly significant in the case of defective management of solid waste dumps

located near the higher courses of rivers that form part of a water basin used for

water supplies to cities downstream.

Waste disposal in water courses represents an environmental risk that renders

populations vulnerable, especially in the event of natural disasters and particularly so

in the case of flooding.

4.3 Environmental licenses

It is necessary to establish a system for the granting of environmental licenses that

defines responsibilities, establishes criteria for environmental impact assessments and

identifies activities that require a prior environmental impact study, such as the

installation of a sanitary landfill.

Under the legislation of many Latin American countries it is the Environment Ministry

that is responsible for issuing licenses, as for example in Colombia, Chile, Paraguay,

Peru and Brazil.

In Brazil, a federal law establishes National Environmental Policy mechanisms, including

the granting of licenses and the revision of “actually” or “potentially” contaminating

activities. The same law requires that the construction, instalment, enlargement and

operation of establishments or the undertaking of activities that use environmental

resources and are considered as actually or potentially contaminating or degrading to

the environment, are dependent on the prior granting of a license by the competent

provincial body integrated in the National Environmental System, SISNAMA, without

prejudice to other required licenses.

Another legal instrument, echoing the text of the National Environmental Policy law,

establishes that the public authority, in exercise of its regulatory function, must grant

the respective licenses before the establishment of an installation and its operation

can begin. In many cases the renewal of a license is necessary to authorize the re-

commencement of an operation.

With a view to facilitating the granting of licences for new sanitary landfills and refuse

dump recuperation in small and medium-sized municipalities, specific legislation can be

passed that simplifies the processes involved in obtaining environmental licenses and

adapts them to the economic capacity of the Municipal Treasury.

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4.4 Regulations applicable to solid waste

In other Latin American and Caribbean countries there are legal instruments applicable

to solid waste management that:

! prohibit the entrance into the country of waste material for final disposal or

incineration;

! establish a system for the granting of environmental licenses, regulate all related

aspects and establish criteria for determining which jurisdictions issue them;

! create security zones around airports that restrict the establishment within them of

operations that attract birds;

! define the responsibilities of and criteria for environmental impact assessments

and identify activities that require an environmental impact study;

! establish criteria for the definition of requirements to obtain licences for works

involving sanitary issues;

! determine appropriate procedures for the handling of damaged, contaminated,

uncategorized or abandoned material that is deemed to be a potential source of

environmental risk, until the relevant environmental body takes responsibility for it;

! regulate environmentally sound initial disposal and management of used batteries,

including their collection, reuse, recycling, treatment and final disposal;

! establish criteria for the granting of licences for industrial activities and for the

specific controls that existent waste, or the generation of waste, should be

subject to;

! regulate the final disposal of discarded car, truck and bus batteries, tyres, used

oils, etc.

! establish the definition and classification of solid waste from healthcare institutions,

ports, airports, railway stations and bus terminals and the minimum procedures for

its management;

! determine a colour code system for different types of waste that must be used for

container identification and in educational campaigns on waste segregation;

! define appropriate treatment and final disposal for medical waste.

Finally, there are aspects of solid waste management that can be subject to technical

regulations, such as:

! the classification of solid waste by its potential risk to the environment and public

health, so that each type of waste can be appropriately handled and disposed of;

! the definition of the minimum conditions required in the planning, establishment

and operation of non-hazardous waste landfills in order to appropriately protect


49

superficial and underground water resources, its operators and neighbouring

residents;

! the definition of criteria for the planning, establishment and operation of hazardous

waste landfills;

! the definition of criteria for the presentation of projects to establish municipal

solid waste controlled landfills;

! the definition of criteria for the presentation of projects to establish municipal

solid waste sanitary landfills.

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5 Solid waste: origin, definitionand characteristics

5. Solid waste: origin, definition and characteristics

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5.1 Definition of rubbish and solid waste

The general public tends to think that “rubbish is everything that is not wanted any

more and is discarded; things that are useless, worn out and without any value.”

Technically, some regulatory entities define rubbish as: “the leftovers from human activity

that are considered useless, undesirable or disposable by the generators and that may be

solid or semi-solid” (substances or products with a humidity content of less than 85%).

The authors of studies on solid waste tend to use the terms “refuse” and “solid waste”

without distinction. In this manual solid waste and refuse comprises all solid or semi-

solid unwanted material that must be collected because the person that discards it

considers it to be of no use and gets rid of it by putting it in any receptacle intended

for that purpose.

It should be emphasized however, that in regard to rubbish the term “of no use” is

relative, as what is of no use for the person who discards it, can be transformed into

raw material for a new product or process. The concept of the reuse of waste therefore

prompts a reconsideration of the traditional concept of solid waste. Only material that

is not reusable by anybody can be truly considered to be rubbish.

5.2 Solid waste classification

Solid waste can be classified in different ways. The more usual classifications take

into account the waste’s potential risk for environmental contamination or its nature

and origin.

5.2.1 Potential environmental contamination risks

Solid waste can be classified as:

CLASS IHAZARDOUS SOLID WASTE

Solid waste that is intrinsically inflammable, corrosive, reactive, toxic or pathogenic and

therefore represents a risk to public health in the form of increased mortality or

morbidity, or produces adverse environmental impacts when inappropriately handled

or disposed of.

CLASS IINON-INERT SOLID WASTE

Combustible, biodegradable or soluble waste that can represent health or environmental

risks but does not fall within Class I, hazardous waste, or Class III, inert waste.

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CLASS IIIINERT SOLID WASTE

Waste with intrinsic characteristics that do not represent a risk to health or the

environment and that when sampled in a representative way in accordance with the

relevant norms and subjected to static or dynamic contact with distillate or deionized

water at room temperature (dissolution tests), does not have any of its dissolved

components in concentrations higher than those in drinking water patterns, except in

regard to aspect, colour, turbidity and taste.

5.2.2 Nature and origin

Origin is the principal element in categorizing solid waste. According to this criterion,

solid waste can be grouped in five categories:

! Residential or domestic waste

! Commercial waste

! Street waste

! Special domestic waste:

! rubble

! batteries

! fluorescent tubes

! tyres

! Special origin waste:

! industrial waste

! radioactive waste

! port, airport, railway station and bus terminal waste

! agricultural waste

! medical waste

RESIDENTIAL OR DOMESTIC WASTE

Waste generated by daily activities in houses, apartments, condominiums and other

types of residential building.

COMMERCIAL WASTE

Waste generated by commercial establishments, the characteristics of which depend

on the particular activities pursued by such establishments.


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In urban cleaning terms, “domestic waste” is made up of “residential waste” and “small-

scale commercial waste” which, together with waste from street cleaning, represents

the majority of solid waste produced in cities.

Commercial waste and construction rubble can both be divided into two sub-categories:

“small generator” and “large generator”.

Municipal urban cleaning regulations can precisely define these two sub-groups. The

parameters could be:

Small commercial waste generators are establishments that generate up to 120

litres of waste per day.

Large commercial waste generators are establishments that generate more than

120 litres of waste per day.

Similarly, small generators of construction rubble are individuals or companies that

generate up to 1,000 kg or 50 bags of 30 litres per day, and large rubble generators are

those that generate a greater volume each day. Clearly these sub-categories cannot be

adopted without also establishing a minimum interval between any two collections of

rubble from the same generator and/or cumulative limits (by volume or weight) for

that generator over a certain period.

In general, the quantity of waste that defines the limit between small and large solid

waste generators should correspond to the average amount of solid waste generated

daily by a household with five residents.

In an urban cleaning system the definition of the sub-groups “small” and “large”

generators is important because a tariff can be applied to the collection of waste

produced by large generators, thus producing an additional source of income that

contributes to the economic viability of the system.

Alternatively it is important to identify large generators so that the waste generated by

them can be collected and transported by a private company authorized by the

municipality. This practice reduces by between 10% and 20% the cost of domestic

waste collection by the municipality.

STREET WASTE

Waste that is found in the streets produced by nature, such as leaves, branches,

dust, soil and sand, and waste discarded by people in a disorganized and improper

way, such as rubble, articles considered to be of no more use, paper, packaging

and food remains.

54

Street waste is directly related with the aesthetic appearance of a city and special

attention should therefore be paid to planning street cleaning services in tourist

cities.

SPECIAL DOMESTIC WASTE

This category consists of construction rubble, batteries, fluorescent tubes and tyres.

It is important to emphasize that construction rubble, also known as civil construction

waste, only comes under this category due to the large amounts in which it is generated

and the importance that its recovery and recycling is acquiring globally.

Rubble

The civil construction industry uses more natural resources and generates more waste

than any other. In many countries commonly used construction techniques for new

buildings involve a waste of materials. While in developed countries the average waste

produced in the construction of new buildings is less than 100kg per m², in Brazil, for

example, the corresponding figure is approximately 300kg per m².

Such material represents 50% of the total weight of municipal solid waste that is collected

in cities of the region with more than 500,000 inhabitants.

Civil construction waste is a mixture of inert materials such as concrete, mortar, wood,

plastic, cardboard, glass, metal, ceramics and soil.

Source: USP – University of Sao Paulo.

Mortar 63.0

Concrete and concrete blocks 29.0

Others 7.0

Organic waste 1.0

Total 100.0

Table 2

Average composition of constructionrubble in Brazil

Components Percentage (%)


55

Batteries

The basic principle of a battery is the conversion of chemical energy into electrical

energy using metals. They can have different shapes (cylindrical, rectangular, button

cell) and sizes and contain one or more of the following metals: lead (Pb), cadmium

(Cd), mercury (Hg), nickel (Ni), silver (Ag), lithium (Li), zinc (Zn), manganese (Mn) and their

compounds.

The substances in batteries that contain these metals are corrosive, reactive and toxic,

and are classified as “Class I - Hazardous Waste”.

Substances that contain cadmium, lead, mercury, silver and nickel have a negative

impact on the environment and particularly on human health. Other metals found in

batteries such as zinc, manganese and lithium can also cause environmental problems,

see table 3.

* Even in small amounts

! gingivitis, salivation, diarrhoea (with blood in the faeces)

! abdominal pains (especially epigastria, vomiting,

metallic taste in the mouth)

! congestion, lack of appetite, indigestion

! dermatitis and arterial hypertension

! stomatitis (inflammation of the mouth mucosa), pharynx and

oesophagus ulceration, kidney and digestive tract lesions

! insomnia, headaches, collapse, delirium, convulsions

! brain and neurological lesions that produce psychological

problems

Table 3

Contaminant potential of chemical elements used in batteries

Element Effects on human health

! abdominal pains (colic, spasm and rigidity)

! kidney malfunction

! anaemia, pulmonary problems

! peripheral neuritis (paralysis)

! encephalopathy (somnolence, manias, delirium,

convulsions and coma)

! digestive problems (nausea, vomiting, diarrhoea)

! kidney malfunction

! pulmonary problems

! poisoning (when ingested)

! pneumonitis (when inhaled)

! cancer

Pb (lead)*

Hg (mercury)

Cd (cadmium)*

56

Batteries made with non-toxic substances are now available on the market and these

can be disposed of without significant problems together with domestic refuse.

Fluorescent tubes

Fluorescent tubes, both the common cylindrical tubes and the compact fluorescent

bulbs, contain mercury steam and release mercury when they are broken, burned or

buried in sanitary landfills. Consequently they are classified as Class I hazardous

waste because mercury is a toxic substance that attacks the human nervous system

and when inhaled or ingested can provoke an enormous variety of physiological

problems.

When mercury is released into the environment and enters bodies of water

“bioaccumulation” takes place, a progressive increase in mercury concentrations in the

tissue of for example fish, which then become less healthy or even dangerous to

consume. When pregnant women eat such fish mercury is transferred to the foetus,

which is particularly sensitive to its toxicity. An accumulation of mercury can also occur

in the tissues of other wild species such as aquatic birds and animals.

Mn (manganese)

Ag (silver)

Li (lithium)

Zn (zinc)

Element

! pulmonary disturbances

! can produce residual damage without immediate treatment

! contact with eyes – causes serious lesion even with

immediate attention

Effects on human health

Table 3 (cont.)

! neurological system malfunctions

! neurological disturbances

! stammering and insomnia

! digestive disturbances and mouth impregnation

! argyria (chronic intoxication producing bluish skin colour)

! death

! inhalation – causes damage even with immediate attention

! ingestion – minimal residual damage without treatment

! cancer

! dermatitis

! general intoxication

Ni (nickel)


57

Tyres

The inappropriate disposal of tyres generates many environmental problems. If left in

the open air, tyres accumulate rainwater and serve as a breeding place for mosquitoes

thus fostering their proliferation. If they are disposed of in conventional landfills, they

will cause hollows in the mass of waste and increase landfill instability. If incinerated,

the rubber generates huge amounts of particles and toxic gases requiring a very efficient

and expensive gas treatment system. For all the above reasons, the disposal of tyres

has become a serious environmental problem that still does not have a truly effective

solution.

SPECIAL ORIGIN WASTE

Waste that due to its particular characteristics requires special handling, preparation,

storage, transport and final disposal. The main types of special origin waste are:

Industrial waste

Waste generated by industrial activity. Its composition varies greatly according to the

type of product that is being made. Consequently it is necessary to examine each

case individually in order to categorize it as Class I (hazardous), Class II (non-inert) or

Class III (inert).

Radioactive waste

Waste that emits radiation in excess of limits stipulated by environmental law.

Due to its specific nature and dangerous characteristics its handling, storage and

final disposal are the responsibility of national public bodies and are subject to

very rigorous controls. In Brazil, for example, the handling, storage and final disposal

of radioactive waste is undertaken by the National Nuclear Energy Commission

(CNEN, in Portuguese).

Port, airport, railway station and bus terminal waste

This category comprises waste generated in terminals as well as in boats, airplanes,

trains and buses. Waste from ports, airports and terminals results from consumption

by passengers in transit and its hazardous nature lies in the risk of transmission

of diseases already eradicated from a country when the incoming transports come

from an area where such diseases are endemic. Transmission can also take place

through potentially contaminated loads, such as animals, meat and plants.

58

Table 4

Classification of medical waste

Class A – Infectious waste

Type Name Characteristics

Blood and bloodderivatives

Surgical, anatomical-pathological andexudates

Sharp andpuncturing

Contaminatedanimals

Patient care

A.1

A.3

A.5

A.2

A.4

A.6

Cultures, inoculae, a mix of micro organisms and aninoculated culture medium coming from clinical or re-search laboratories, vaccine that is unusable or pastits use-by date, filters used to prevent inhalation ofgases in areas contaminated by infectious agents andany refuse contaminated by the above materials.

Blood and blood derivatives past their use-by date,HIV- positive blood, blood used for analysis, serum,plasma and other derivatives.

Tissue, organs, foetuses, anatomical parts, blood andother organic liquids resulting from surgery and autop-sies, and waste contaminated by the above materials.

Needles, ampoules, pipettes, scalpel blades and glass.

Skeletons or parts of animals that have been inocu-lated, exposed to pathogenic micro-organisms or arecarriers of infectious diseases, as well as waste thathas been in contact with them.

Secretions and other organic liquids from patients,as well as waste contaminated by them, including re-mains of food.

Biological

Agricultural waste

This category mostly comprises the remains of containers and packaging impregnated

with dangerous pesticides and chemical fertilizers used in agriculture. The handling of

this type of waste should therefore follow the same practices and use the same

containers and process as those used for the handling of Class I industrial waste. Due

to a lack of controls and low fines for inappropriate handling of this type of waste, it

is often mixed with common waste and disposed of in municipal dumps or even worse,

thrown into bodies of water or is burnt in remote rural establishments thus generating

toxic gases.

Medical waste

This category consists of all the waste generated by healthcare institutions. The

classification of medical waste according to Brazilian standards (NBR 12.808 of the

Brazilian Association of Technical Standards, ABNT) is presented as an example in

table 4.


59

5.3 Characteristics of solid waste

Solid waste characteristics can vary according to the social, economic, cultural,

geographical and climatic factors that distinguish one community from another and

even one city from another.

Table 5 shows the variation in waste composition in some particular countries from

which it can be deduced that the percentage of organic matter tends to diminish in

more developed or industrialized countries, probably due to the large amount of semi-

prepared food available in the market.

Waste can be analyzed according to its physical, chemical and biological characteristics.

5.3.1 Physical characteristics

Solid waste can be categorized according to the following physical characteristics: per

capita generation, gravimetric composition, apparent specific weight, humidity content

and compressibility.

Waste that does not fall into classes A or B and that,due to its similarity with domestic waste, does notpresent any additional risk to public health.

Table 4 (cont.)

Common wasteC

Radioactive material or material contaminated withradionuclide, originating in clinical analysis laborato-ries, nuclear medicine services and radiotherapy.

Medicine that is past its use-by date, contaminated,interdicted or of no further use.

Toxic, corrosive, inflammable, explosive, reactivegenotoxic or mutagenic waste.

Class B – Special waste

Class C – Common waste

B.1

B.2

Radioactivewaste

Hazardouschemical waste

Pharmaceuticalwaste

B.3

Type Name Characteristics

65.00

3.00

4.00

3.00

25.00

61.20

10.40

3.80

5.80

18.80

50.30

14.50

6.70

6.00

22.50

35.60

8.20

8.70

6.50

41.00

Organic matter

Glass

Metal

Plastic

Paper

Component Brazil Germany The Netherlands USA

Gravimetric composition of waste in some countries (%)

Table 5

60

Figure 4 - Variation in per capita solid waste generation in relation to population size

PER CAPITA GENERATION

The relation between the amount of solid waste produced in a given region per day

and the number of inhabitants in that region. In the absence of precise data, per capita

generation can be estimated through table 6. However, the ideal is to carry out field

research and, based on statistical data, determine the daily waste generation per

inhabitant in relation to the population’s socioeconomic profile.

Like table 6, figure 4 shows the correlation between the per capita generation of solid

waste and the population of cities. Although representative of averages determined

by several studies, these parameters should be considered with certain reservations

as particular local conditions may produce distortions in individual cases.

0.50

from 0.50 a 0.80

from 0.80 a 1.00

over 1.00

Small

Medium-sized

Large

Megalopolis

Up to 30,000

from 30,000 a 500,000

from 500,000 a 5,000,000

over 5,000,000

Tabla 6

Size ofthe city

Urban population(inhabitants)

Generation per capita(kg/inhab/day)

Frequently used categories for determining per capita solid waste generation


61

Organic matter Ferrous metals Rubber

Paper Non-ferrous metals Leather

Cardboard Aluminium Cloths

Rigid plastic Transparent glass Bones

Malleable plastic Coloured glass Ceramics

PET Wood Fine aggregate

Table 7

Most common components in gravimetric composition

GRAVIMETRIC COMPOSITION

Gravimetric composition indicates the percentage of the total weight of an analyzed

waste sample that each component represents. The most commonly used categories

in the determination of the gravimetric composition of municipal solid waste can be

found in table 7.

However, many technicians tend to simplify the categories, for example considering

only paper/cardboard; plastic; glass; metal; organic matter and “other”. This type of

simplified category list, although useful for determining the dimensions of a composting

plant or other urban cleaning system installations, is not ideal in a precise economic

study for recycling or selective collection as, for example, the market for rigid plastics

is very different from the market for malleable plastic, as are the markets for ferrous

and non-ferrous metals.

The decision about which components to include in a gravimetric composition study is

made on the basis of the type of study to be carried out and must involve great care

to avoid distortions.

APPARENT SPECIFIC WEIGHT

The apparent specific weight is the weight of loose waste in relation to the volume

that it freely occupies without any form of compacting and is expressed in kg/m³. It is

fundamental for determining the dimensions of necessary equipment and installations.

If precise data is not available, the following general specific weight values can be

used: 230 kg/m³ for domestic waste, 180 kg/m³ for medical waste and 1300 kg/m³ for

construction rubble.

However, it is necessary to carefully evaluate the specific situation before adopting

these values as variations exist in peoples customs and practices across the different

regions and countries of Latin America and the Caribbean.

62

HUMIDITY CONTENT

The humidity content is the amount of water contained by solid waste, measured as a

percentage of its weight. This parameter can vary by between 40% and 60 % depending

on the season and amounts of rainfall.

COMPRESSIBILITY

Compressibility is the degree of compacting that is possible, that is, the reduction of

volume that can be achieved in a mass of solid waste when it is compacted. Subjected

to a pressure of 4kg/cm², on average the volume of waste can be reduced to between

a third (1/3) and a quarter (1/4) of its original volume.

When the compacting pressure is withdrawn the mass of solid waste tends to expand

but it does not return to its original volume. This phenomenon, called expansion, must

be heeded when operating a landfill.

5.3.2 Chemical characteristics

CALORIFIC VALUE

This chemical characteristic indicates the potential heat generating capacity of a material

when incinerated. The average calorific value of domestic solid waste is approximately

3,000 kcal/kg.

POTENTIAL OF HYDROGEN (pH)

The potential of hydrogen indicates the acidity or alkalinity of waste which is generally

found to be between 5 and 7.

CHEMICAL COMPOSITION

The chemical composition indicates the amount of ashes, organic matter, carbon,

nitrogen, potassium, calcium, phosphorus, total mineral residue, soluble mineral residue

and fats contained in solid waste.


63

Table 8

Influence of waste characteristics on urban cleaning

Characteristics Importance

Per capitageneration

This data is fundamental for estimating the amount of

waste to be collected and disposed of. It is important

for determining vehicle and machine capacity

requirements, tariffs charged for collection and the

necessary capacity of all the units that comprise the urban

cleaning system.

CARBON/NITROGEN RATIO (C/N)

The Carbon/Nitrogen ratio indicates the degree of decomposition of solid waste organic

matter in treatment and final disposal processes. In general for domestic waste that

ratio is around 35/1.

5.3.3 Biological characteristics

Solid waste biological characteristics are determined by the microbial and pathogenic

agent populations and, together with the chemical characteristics, inform the selection

of appropriate treatment and final disposal methods.

Knowledge of the biological characteristics of solid waste has been extensively

utilized to develop odour inhibitors and substances used to delay or accelerate

the decomposition of organic matter, which are generally applied inside collection

vehicles to avoid or minimize problems caused to people along the routes of the

vehicles.

Similarly, final disposal and degraded site recuperation processes are being developed

based on the biological characteristics of waste.

5.4 Influence of solid waste characteristicson urban cleaning system planning

Table 8 illustrates the influence of solid waste characteristics on urban cleaning system

planning and on the design of certain units that form part of the system.

64

Table 8 (cont.)

Apparentspecific weight

Humidity content

Compressibility

Calorific value

pH

Chemicalcomposition

Biologicalcharacteristics

C/N ratio

Gravimetriccomposition

Indicates the potential for the commercialization of recy-

clable components, the use of organic matter to produce

compost and the application of other processes to the

solid waste.

Fundamental to correctly quantifying the required capacity

of the collection fleet, mobile and fixed containers and

other collecting equipment.

Directly influences the decomposition rate of matter in the

composting process. Directly influences the calorific value

and apparent specific weight of solid waste, thereby indi-

rectly influencing the determination of required incinerator

and composting plant capacity. Directly influences the cal-

culation of percolate production and the required capacity

of the percolate collection system.

Very important for determining the required capacity of

collection vehicles, transfer stations with waste compac-

tion facilities and fixed compaction containers.

Influences the determination of the required capacity of

installations for all thermo treatment processes (incinera-

tion, pyrolysis, etc.).

Indicates the degree of corrosiveness of collected waste

and is used to establish the type of protection against cor-

rosion that it is necessary to apply to vehicles, machines

and metal containers and boxes. An important indicator in

the solid waste decomposition process in treatment and

final disposal units.

Important for determining the potential risk posed by solid

waste to human health and the environment. Contributes

to the determination of the most appropriate form of treat-

ment for collected waste.

Fundamental to the evaluation of composting process evo-

lution and determining the quality of the compost produced.

Important in determining the sanitary risk posed by solid

waste. Fundamental for the identification of odour inhibi-

tors and substances to accelerate or delay the decompo-

sition of organic matter in solid waste.

Characteristics Importance


65

5.5 Factors that influence solid waste characteristics

Clearly during rainy periods the humidity content in solid waste increases and during

the celebrations around the end of the year, and throughout the summer, the percentage

of aluminium (beer and cold drinks cans) in the waste increases. Consequently it is

necessary to take into account seasonal factors that can influence particularly the

physical characteristics of solid waste in order to avoid wrong conclusions in determining

the overall characteristics of waste.

Bank holidays and school holidays have an influence on the quantity of solid waste

generated in tourist cities.

Table 9 shows the principal factors that have a strong influence on solid waste

characteristics.

Principal factors that influence solid waste characteristics

Table 9

Factor Effect

Climatic/seasonal

Special periods

Demographic

Christmas /

New Year

School holidays

Other festivals

Urban population

size

Rain

Autumn

Summer

! increase in humidity content

! increase in leaf content

! increase in drinks container content (cans,

glass and rigid plastic bottles)

! increase in packaging content (paper/

cardboard, malleable plastic and metal)

! increase in organic matter content

! population decrease in non-tourist areas

! population increase in tourist areas

! increase in drinks container content (cans,

glass and rigid plastic bottles)

! the larger the urban population the greater the

per capita solid waste generation

66

5.6 Processes for determining principal physical characteristics

Amongst the various types of solid waste characteristics the physical ones are the

most important to identify for proficient urban cleaning services management.

Not all municipalities can afford to set up laboratories to determine the chemical or

biological characteristics of solid waste, or have the financial resources to contract

private laboratories. The physical characteristics however can be easily determined

through processes undertaken in the field and only require: 200 litre metal containers,

a 150 kg capacity weighing machine, an oven and tools and implements commonly

used in urban cleaning.

The practical procedures presented below are employed to determine municipal

solid waste specific weight, gravimetric composition, humidity content and per capita

generation.

SAMPLE PREPARATION

! collect initial samples with a volume of 2 to 3m³ from un-compacted solid waste

(loose refuse); the samples must be taken from different collection sectors to

obtain results that are as realistic as possible;

Socioeconomic

Purchasing power ! the higher the purchasing power of the

population, the higher the proportion of

recyclable material and the lower the

proportion of organic matter

! greater consumption of luxury goods

immediately after payday (end and beginning

of month)

! greater consumption of luxury goods at

weekends

! reduction in apparent specific weight of waste

due to the introduction of increasingly lighter

products

! increase in the amount of packaging

Purchasing power

(monthly)

Purchasing power

(weekly)

Technological

development

Commercial

promotions

Table 9 (cont.)

Factor Effect


67

! deposit the initial samples on a sheet of canvas extended on flat land and mix them

until obtaining one homogeneous pile, using shovels and hoes to rip plastic bags

and break cardboard boxes, crates and other materials used to package the waste;

! divide the pile of homogenized waste into four equal parts and select two of them

(always opposite quarters, not adjacent ones). Mix these two parts homogenizing

the content (the remaining two quarters should be sent for final disposal in the landfill);

! repeat the previous procedure until the volume of each of the quarters is just

over 1m³:

! separate one quarter at random and use it to completely fill five previously weighed

200 litre metal containers;

! after filling the containers, break up the rest of the selected quarter with machetes

in a place that is protected from the elements (sun, rain, wind or high temperature);

fill a two litre container with the broken up material and close the container as

hermetically as possible.

APPARENT SPECIFIC WEIGHTDETERMINATION

! weigh each of the filled 200 litre containers and determine the net weight of the

waste subtracting the weight of the container;

! add up the net weights;

! determine the apparent specific weight (expressed in kg/m³) by dividing the total

net weight of the waste in the five containers (in kg) by the total volume of the 5

containers, i.e. 1m³.

GRAVIMETRIC COMPOSITIONDETERMINATION

! define the list of components to identify depending on the objectives;

! spread the contents of one of the containers on a canvas sheet extended on

flat land;

! separate the waste according to the defined list of components;

! classify as “other” all material found that does not fall into any of the categories on

the predefined list of components;

! weigh each component separately;

! divide the total weight of the sample by the weight of each component and calculate

the percentage of each component in relation to the whole in order to determine

the gravimetric composition.

68

HUMIDITY CONTENTDETERMINATION

! weigh the two litre sample;

! put the sample in an oven at 105ºC for 24 hours or at 75º C for 48 hours;

! weigh the dry material repeatedly until the weight remains constant;

! subtract the dry material weight from the humid sample weight thus determining the

percentage of humidity.

CALCULATION OFPER CAPITA GENERATION

The per capita generation of solid waste can be determined by means of field

studies on households pre-selected on the basis of appropriate statistical data so

that they are representative of the overall socioeconomic profile of the population,

or by means of procedures undertaken at the final disposal site that produce

relevant data.

The following is a simplified calculation methodology for use in cities without a

weighbridge to weigh solid waste on arrival at the final disposal site.

! measure the volume of waste taken to the landfill during one working week;

! convert the total volume (in m³) of waste that has arrived at the landfill into total

weight (in kg), using the specific weight value determined by applying the technique

described in a previous section;

! estimate the percentage of the population served by the collection service;

! based on the above percentage and the total number of inhabitants in the city

calculate the number of inhabitants served by the collection service;

! calculate the per capita generation rate by dividing the total weight of waste (in kg)

by the number of inhabitants served and then dividing this result by seven to obtain

the daily rate.

The following observations are significant:

! sample collection and the measurement of waste being taken to a landfill must

never be undertaken on a Sunday or Monday as, due to collection patterns, these

are atypical days for the purposes of determining waste generation;


69

! in tourist cities samples should never be taken during school holidays or bank

holidays, unless a determination of seasonal influence on the city’s waste generation

is required;

! never measure humidity content on a rainy day;

! where possible measurements should always be taken between the 10th and the

20th of a month to avoid distortions nearer the end of a month.

70

6 Solid waste quantity projections

6. Solid waste quantity projections

71

For an accurate solid waste generation projection, it is necessary to have demographic

data on the resident and seasonal populations, especially in tourist cities where tourists

can sometimes generate more solid waste than permanent residents.

It is important to have data on seasonal fluctuations in population numbers and to

take this into account when making projections for solid waste generation in tourist

cities.

A careful analysis should be made of up to date demographic data in order to make

reliable population projections (see table 10) and calculate solid waste production

over time.

The following example shows procedures to be followed.

Let us suppose that a projection is required for an urban cleaning system in a non-

tourist city with a current urban population of 50,000 that is growing at an annual

rate of 3% and where the per capita waste generation has been measured as 530g/

inhab/day.

With a projection horizon of 20 years population values would be as in table 10:

It is known that the greater the economic development of a city (in general related

to population size), the larger the per capita solid waste generation. Therefore, in

Table 10

Current

1

2

3

4

5

6

7

8

9

10

Year Urban population(inhabitants)

Year

Demographic projection

50,000

51,500

53,045

54,636

56,275

57,963

59,702

61,493

63,338

65,238

67,195

11

12

13

14

15

16

17

18

19

20

69,211

71,287

73,426

75,629

77,898

80,235

82,642

85,121

87,675

90,305

Urban population(inhabitants)

72

such a case the evolution of the per capita production would be estimated as in

table 11:

Thus the projected amount of solid waste produced daily over 20 years is as in

table 12:

Per capita (g/inhab/day)Period

Table 11

Evolution of per capita solid waste generation

530

540

550

Year 1 to 7

Year 8 to 14

Year 15 to 21

26.5

27.3

28.1

29.0

29.8

30.7

31.6

33.2

34.2

35.2

36.3

37.4

38.5

39.7

41.6

42.8

44.1

45.5

46.8

48.2

49.7

Table 12

Current

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

YearDemographic projection

(inhabitants)Per capita(g/inhab./day)

Amount ofwaste (t)

Projected amount of solid waste generation

50,000

51,500

53,045

54,636

56,275

57,963

59,702

61,493

63,338

65,238

67,195

69,211

71,287

73,426

75,629

77,898

80,235

82,642

85,121

87,675

90,305

0.53

0.53

0.53

0.53

0.53

0.53

0.53

0.54

0.54

0.54

0.54

0.54

0.54

0.54

0.55

0.55

0.55

0.55

0.55

0.55

0.55

6. Solid waste quantity projections

73

When an Integrated Solid Waste Management Plan is formulated, it is common to consider

a five year projection horizon for planning waste collection and the cleaning of streets

and other public spaces. A five year horizon is used because changes in a city’s

urbanization are significant over a period of time greater than that, especially in medium-

sized and large cities in Latin America and the Caribbean. At the end of the five years

an assessment of the situation is made and if necessary planning is updated.

For projections relating to solid waste treatment and final disposal a 15 year term is

more common.

74

7 Solid waste preparation and storage

7. Solid waste preparation and storage

75

Figure 5 – Open air solid waste accumulation point

7.1 Concept

Pre-collection solid waste preparation and storage should be done in an appropriately

sanitary way taking into account the type and quantity of waste

7.2 The importance of appropriate preparation and storage

The quality of solid waste collection and transportation operations depends on an

appropriate preparation and storage of waste and its presence in the place, on the day

and at the time established by the urban cleaning body responsible for collection.

Citizens participation in this operation is therefore of great importance.

Appropriate preparation and storage is important for:

! avoiding accidents;

! avoiding vector proliferation;

! minimizing visual and odour impacts;

! reducing waste heterogeneity (in the case of selective collection);

! facilitating collection.

In many cities open air domestic waste accumulation points appear spontaneously causing

scattered refuse in the streets, damage to the environment and a risk to public health.

Incorrectly prepared and stored solid waste attracts animals.

In urban zones of low quality dwellings and low demographic density there are generally

more animals, such as dogs, horses and pigs, that roam freely in the streets and

frequently tear rubbish bags and knock down containers to access the remains of

food, which results in waste being scattered over a large area. In addition such domestic

waste attracts rats, mice, flies, cockroaches and other disease vectors that feed and

breed in the refuse.

76

To limit damage caused by the activities of such animals it is recommended that:

! the municipality implements regular operations to remove animals that are free in

the streets;

! refuse collection is more frequent and regular in such zones;

! inhabitants of such zones are instructed to put refuse out in the street at a time as

close as possible to the collection time;

! a more appropriate type of container is provided for the solid waste, with special

anchoring devices that enhance their stability;

! the relevant public body takes action to contain the proliferation of rats and mice.

In Latin American and Caribbean cities diverse containers are used for putting out and

storing domestic waste for collection:

! metal or plastic bins;

! plastic bags, supermarket type or specifically for refuse;

! wood or cardboard boxes;

! used oil and fuel drums, sometimes cut in half;

! large metal or plastic containers, stationary or on wheels.

There are also creative initiatives for storing this type of waste. An example can be

found in cities in the north and northeast of Brazil, where alternative containers are

skilfully made with old tyres. This is a way of using discarded tyres but the containers

are heavy and not very practical, however they are acceptable in the context of the

socioeconomic conditions that prevail for most inhabitants there.

7.3 Characteristics of pre-collection storage containers

The choice of container type should be based on:

! refuse characteristics;

! quantity of refuse generated;

! frequency of collection;

! type of building;

! price of container.

Receptacles for domestic waste pre-collection storage should have the following

characteristics:

! a maximum loaded weight of 30 kg if the collection is manual;

Larger containers should be standardized so that they can be handled by mechanical

devices incorporated in the collector vehicles in order to reduce manual labour.


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! devices that facilitate its movement between its place in the building and the place

of collection;

! closable in order to avoid waste spillage or exposure;

Flexible packaging (plastic bags) should be closable. Rigid and semi-rigid receptacles

(plastic and metal bins, containers) should have lids and be stable enough that they are

not easily knocked over.

! safe in that injury is not caused to users or collectors by sharp edged or pointed

waste, including when separately packaged;

! economical and affordable for the general public;

! not producing excessive noise when handled;

! easy to empty without leaving waste at the bottom.

From a planning perspective another characteristic has to be taken into account:

whether the receptacles are returnable or non-returnable.

In the latter case collection will be more efficient, after collection there will be no

receptacles left on the street and residents will not need to clean receptacles.

For these reasons, it can be concluded that plastic bags are the most convenient

receptacles for storing domestic waste prior to manual collection because:

! they are easy to close by tying;

! they are light, non-returnable (so collection is more efficient) and allow for silent

collection, an important factor particularly for nocturnal collections;

! their price is affordable and they can be standardized.

In Latin American and Caribbean cities where the income level of most inhabitants is

low, the use of supermarket plastic bags (used for transporting purchased products to

the home) can be acceptable for the pre-collection storage of domestic waste as they

do not involve any extra cost.

From an environmental perspective there are usually reservations about the use of

plastic bags for domestic waste storage, especially in connection with waste incineration

processes. However, polythene bags do not contaminate the atmosphere when

appropriately incinerated. Another issue is that most plastic bags are non-biodegradable,

but as the use of sanitary landfills is a practically definitive waste disposal method,

there are not many objections to their use.

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In regard to the safe handling of plastic bags containing waste, appropriate procedures

to reduce the risk of injury to collectors must always be observed, it being fundamental

for example, that they wear appropriate protection gloves. Plastic bags with a capacity

of more than 100 litres are not safe as collectors tend to hold them against their

bodies while carrying them to the truck and pieces of glass and other sharp objects in

the waste can injure them.

For multi-family housings (apartment blocks) and office blocks standardized wheelie

bins with lids are more appropriate as they allow for semi-automatic collection, which

is more efficient and safer. These containers are easy to handle as they have wheels,

are light, relatively silent, and economical due to their durability (especially if not exposed

permanently to sunlight) and have a pleasing appearance. There are wheelie bins of

120, 240 and 360 litre capacity on the market.

Figure 6 – Standardized wheelie bins

7.4 Domestic waste pre-collection preparation and storage

The most appropriate containers for pre-collection domestic waste storage are plastic

bags, wheelie bins and metal containers.


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Figure 7 – Plastic wheelie bin

Figure 8 – Metal container

Plastic bags

Waste can be stored in non-returnable plastic bags to be collected by collection vehicles.

Such plastic bags should have the following characteristics:

! resistance so that they do not break when handled;

! a capacity of 20, 30, 50 or 100 litres;

! a tape to close the top;

! a colour standardized by the relevant body

In general these characteristics are regulated by technical standards.

Plastic wheelie bins

These are containers made of high density polyethylene (HDPE) with a capacity of 120,

240 or 360 litres (two wheeled bins) and 760 or 1,100 litres (four wheeled containers),

comprising a body, a lid and wheels. They are made of partly recycled material plus

additives to protect them from the action of ultraviolet rays.

They are used for the storage and transport of domestic waste, but can also be used

for certain public waste (for example when they are used to store the waste from

street sweeping).

Domestic waste produced by large generators – the

collection and transport of which should be undertaken

if possible by private companies authorized by the

municipality – can be stored in containers similar to the

one in figure 7, different only in their colour from those

for residential waste.

Metal containers

These receptacles, with a capacity that ranges

between 750 and 1,500 litres, generally have

four small wheels and can be emptied by

means of tipping devices installed in

compaction trucks.

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Figure 9 – Mechanized metal container tipping

7.5 Pre-collection storage of street waste

Rubbish bins

There are several types of container that can be installed in the street for passers-by

to deposit rubbish, in order to maintain the city in a hygienic and clean condition.

For many years this type of container was metallic and was of a shape and colour

determined by municipal administrations. The high costs of the production, maintenance

and replacement of these metal bins were an obstacle to them being more widely

used.

Currently plastic rubbish bins are increasingly used as they are lighter, more durable,

easier to install and cheaper.

Such rubbish bins have a capacity of 50 litres and consist of a body in which rubbish is

deposited, a lid and a metal tray to stub out cigarettes before throwing them into the

bin. They are made of partly recycled material plus additives to protect them from the

action of ultraviolet rays.

These containers should be installed in parks, squares, public gardens, streets, avenues

and other public spaces that people pass through.

This type of bin can be used for other purposes. For example, a growing environmental

awareness in society is resulting in the separation of used batteries that, due to an

ever intensifying use of portable electrical and electronic gadgets, are becoming

increasingly numerous. In this context the use of plastic rubbish bins with a 50 litre

capacity, a standardized colour and a special hole in the front part of the lid represents

a good option for storing discarded batteries.


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Figure 10 – Rubbish bin Figure 11 – Battery bin

Figure 12 - – Dumpster carrier truck with multifunction crane transporting stationary container

Plastic bags

Plastic bags similar to those used for residential waste can be used for the pre-collection

storage of public waste.

The difference is that bags for public waste, particularly that collected by sweeping,

can be bigger.

Construction rubble requires the use of thicker plastic bags with less volumetric capacity

due to the higher specific weight of the material to be stored.

Wheelie bins /stationary containers

As with plastic bags, plastic containers for public waste are exactly like those used for

storing residential waste. However metal containers are different.

Metal containers used for public waste pre-collection storage are stationary receptacles

generally with a volumetric capacity of 5 or 7 m³ that can be emptied by compactor

trucks (depending on the nature of the waste) or by dumpster carrier trucks equipped

with a multifunctional crane to load and unload the containers.

This type of container is interchangeable and the vehicle that collects a full container

brings an empty one to replace it. This system is also known as “brooks” or “dumpster”.

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Figure 13 – Brooks dumpster outside a low income community settlement

7.6 Pre-collection storage of waste in lowdemographic density and low-income areas

In informal settlement dwellings and low-income housing estate households there is

usually little space for storing waste. Consequently as waste is produced it is taken

out of the houses and put on the street, which results in the above mentioned

environmental and sanitary problems.

In such circumstances standardized plastic containers (with wheels and lid) can be

located at previously determined points with as frequent collections as possible.

If it is not possible to provide plastic containers, one alternative is to provide brooks

type dumpsters. However experience demonstrates that this type of container does

not produce satisfactory results as, amongst other problems, waste becomes scattered

around it, animals forage in it, there can be fires due to acts of vandalism and a bad

odour is produced.

Such problems result from a series of factors, one of which is the design of the

containers that in general do not have a lid, and when they do have one, users tend to

ignore it. For all the above reasons, when this type of storage is adopted containers

must be changed at appropriately frequent and rigorously observed intervals in order

to maintain the cleanliness of the area, awareness raising campaigns should be instigated

in the community and an efficient supervision system should be set up.

Compaction containers represent a more appropriate solution than brooks dumpsters

for pre-collection storage of domestic solid waste in such special areas. They are

stationary closed metal containers with an incorporated waste compaction device,

and are handled by special vehicles. Their use depends on the amount of waste

generated by a community and the technical, operational and economic capacities of

the municipality.


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Figure 14 – Compaction container system

It is advisable to establish a team of workers to operate a system for maintaining clean

and hygienic conditions in the most problematic poor communities.

In some cities, Rio de Janeiro for example, contracts are established with residents

associations in low income communities whereby they undertake the operation of

domestic waste collection and cleaning services for internal streets. One of the

conditions of this type of contract is that local labour is employed so that local jobs

are generated and the community’s awareness of these issues increases as it becomes

directly responsible for the cleaning of the settlement. The body responsible for

urban cleaning pays for the services undertaken, provides technical support and

supervises the quality of the operation. The associations hire their own employees

and are responsible for the management of the work. Satisfactory results from this

type of program have led to its implementation in almost all of Rio de Janeiro’s informal

settlements.

7.7 Pre-collection storage of waste produced by large generators

Where a specific regulation specifies that commercial and industrial establishments

generating more than 120 litres of solid waste per day are categorized as “large generators”,

containers for the pre-collection storage of such waste should be standardized.

The limit of 120 litres was established to correspond with the capacity of the smallest

plastic container with lid and wheels that is available on the market.

It is practical for containers used by large generators to be different in colour and size

from those used for normal collections in order to facilitate supervision (for example,

blue containers for large generators and orange containers for normal collections).

For collections from large generators and public establishments, in general two main

types of large container with a capacity of more than 360 litres are used:

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Figure 15 – Double dumpster carrier truckwith interchangeable containers

Figure 16 Roll-on /roll-off truck

! metal or plastic (high density polyethylene) containers on wheels that are taken to

collection vehicles and mechanically emptied into them. In general these containers

have a capacity of 760, 1,150 or 1,500 litres.

! stationary containers without wheels, generally metal, that are interchangeable or

are emptied into collection trucks. Containers of up to 5m³ are emptied into collection

trucks by means of steel cables powered by hydraulic devices.

Interchangeable containers are moved by dumpster carrier trucks with multifunctional

cranes or by roll-on /roll-off type trucks. These metal containers have a capacity of 3

to 30 m³. The very large containers (20 to 30 m³) are moved by roll-on/roll-off truck

equipment either with steel cables pulled by a winch or by hydraulic cylinders, and can

be equipped with electric devices for compaction, in which cases they are informally

referred to as “compactainers”.

7.8 Special domestic waste pre-collection storage

Construction rubble

Due to its high apparent specific weight, construction rubble is normally stored in

stationary metal containers of 4 or 5m³, similar to those used for storing public waste.

Due to the large volumes of rubble, and therefore the size of containers needed to

store it, a significant problem is caused for the circulation of passers-by and vehicles

as well as for parking vehicles. In addition construction rubble uses a lot of space in

sanitary landfills, space that could be used to deposit non-recyclable types of waste.

Within the concept of sustainable development established by Agenda 21, the

reduction of waste and the reuse of it and its by-products are fundamental to the

new approaches that society must adopt. The biggest challenges presented by

construction rubble are:


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! to reduce the amount of rubble generated thus reducing the use of limited space

available for disposal;

! to reuse generated rubble in the productive cycle thus reducing the consumption

of energy and natural resources.

Batteries

Partially discharged batteries must be stored in such a way that their electrodes do not

come into contact with the electrodes of other batteries or with metal objects such

as the internal sides of a metal drum. Partially discharged nickel-cadmium batteries must

be individually pre-wrapped in plastic bags.

Containers with stored batteries must be sealed to avoid the release of hydrogen,

which is explosive in contact with the air, and must be kept on platforms or pallets in

order to keep them dry. Storage containers should be located in places with good

ventilation and protection from the elements. The large numbers and variety of devices

that use batteries, together with their small size and the general public’s lack of

knowledge about the dangers that they pose, have resulted in them often ending up

together with the general domestic waste in sanitary landfills where they contaminate

the environment.

Due to their toxicity and the difficulties involved in stopping them being discarded in

domestic refuse, responsibility for the storage, collection, transport and final disposal

of batteries should be taken on by producers, importers, commercial outlets and

technical assistance networks.

Any legal measures implemented for the regulation of such a system must set a specific

timeframe for these stakeholders to establish operational mechanisms for the

collection, transport and storage of discarded batteries.

Legislation should also establish a timeframe within which producers and importers of

batteries must implement reuse, recycling, treatment and final disposal systems.

Fluorescent tubes

Fluorescent tubes also require specific legislation to regulate the way in which they

are discarded, stored and handled, and their treatment and final disposal. Such legislation

should reflect the “polluter pays” principle.

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Procedures for handling fluorescent tubes that contain mercury must respect the

following requirements:

! intact tubes should be stored in boxes, if possible plastic ones, in a reserved area

to avoid them being broken;

! all boxes should be labelled;

! tubes should not be broken or physically modified;

! once a sufficient number of tubes has been accumulated they should be sent for

recycling, accompanied by the following information:

! source (name and address of company or institution), details of the

transport company and the recycling company;

! number of tubes sent;

! date dispatched;

! a record of these invoices must be kept for at least three years;

! if a tube breaks, the pieces of glass must be removed and the area must be

washed;

! broken tubes should be stored in sealed containers and labelled in the following

way: “Broken fluorescent tubes containing mercury”.

Tyres

Due to problems associated with the inappropriate disposal of tyres, and following

the example of the system for dealing with batteries, producers and importers of

tyres should be obliged to collect and dispose of discarded tyres in an environmentally

sound way.

One of the principal problems with the storage of tyres for collection or recycling is

that they accumulate water when left out in the open and thus facilitate the proliferation

of disease vectors.

Tyre storage should respect the following guidelines:

! tyres should not be accumulated but should be sent for disposal at the time that

they are discarded;

! if it is necessary to keep them, this should be done in covered areas protected

from the elements;

! they should never be burned.

Discarded tyres have been used as fuel in furnaces for the production of cement and

also to produce asphalt.


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7.9 Special origin waste pre-collection storage

Industrial waste

Industrial waste is usually stored in:

! 200 litre metal drums for non-corrosive solid waste;

! 200 or 300 litre plastic drums for corrosive solid waste or semi-solid waste in general;

! flexible containers, i.e. bags, usually of woven polypropylene, with a large storage

capacity almost always of more than 1m³;

! standardized plastic containers of 120, 240, 360, 750, 1,100 and 1,600 litres for

waste that allows for the use of returnable containers;

! medium-sized cardboard boxes of up to 50 litre capacity for waste to be incinerated.

Radioactive waste

The handling and storing of radioactive waste must comply with the stipulations of the

national body responsible for the control and supervision of this type of waste, which

include the following requirements:

! personnel handling this type of waste must use the obligatory minimum individual

protection equipment;

! containers must be radiation proof (lead, concrete, etc.).

Port and airport waste

From a sanitary perspective ports and airports are places where not only people and

goods disembark but also diseases. It is therefore necessary to establish permanent

sanitary vigilance and handle waste in a particularly hygienic manner.

In normal conditions, handling and storage of waste follows the same procedures and

uses the same receptacles as those for domestic waste. However in cases of quarantine

alert, or other situations of risk identified by the body responsible for sanitary vigilance,

special methods must be applied to the handling of personal waste and goods coming

from countries with epidemics.

Medical waste

The handling of medical waste (see table 4) must follow specific regulations that stipulate

procedures for waste segregation at source, storage and management.

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Figure 17 – Plastic bags for medical waste

The principal procedure is the segregation at source of infectious and common waste.

Infectious waste represents between 10 and 15 % of all waste but carries a high

contamination risk while common waste does not require any special treatment.

A lack of care when handling infectious waste is the principal cause of infections in

hospitals. An example that illustrates this is the case of municipal hospitals in Rio de

Janeiro where, after the introduction of clear infectious waste segregation procedures,

the rate of hospitalization due to such infections diminished by 80%.

Pre-collection storage of common waste follows the same procedures as for domestic

waste.

Infectious waste must in general be put in well identified strong impermeable plastic

bags at the moment of its generation.

Special waste should be stored in receptacles that guarantee its physical integrity.

They should be strong, rigid plastic containers with hermetic lids and a clear identification

of the type of waste that they contain.

Puncturing and sharp waste (needles, glass, etc.) must be separately discarded at

source in rigid containers with hermetic lids and a clear identification of the type of

waste that they contain.

Plastic bags should comply with established colour code specifications. In Brazil the

criteria are the following:

! transparent – common waste, recyclable

! opaque colours – common waste, non-recyclable

! cream – infectious or special waste (except radioactive waste)


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Figure 18 – Infectious waste containers

Figure 19 – Temporary storage facility for infectious wastecontainers

Subsequently the plastic bags must be placed in containers that can be easily moved to

a temporary storage facility. These containers must be white for infectious waste and

any other colour for common waste.

Temporary storage facilities must have tiled floors and walls and rounded corners to

facilitate the washing of floors and walls.

Personnel handling infectious waste (except radioactive and hazardous chemical waste,

which are not the responsibility of urban cleaning systems) should use the following

individual protection equipment (IPE):

! plastic apron;

! plastic gloves;

! PVC boots (for floor and wall washing) or closed shoes;

! goggles;

! mask.

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Solid waste collection and transport8

8. Solid waste collection and transport

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8.1 Domestic waste collection and transport

8.1.1 Concept

Collection is the removal of waste stored by the generator for dispatch by appropriate

transport to a transfer station, treatment unit or final disposal site.

The collection and transportation of domestic waste generated in households and

small-sized public, commercial or service establishments is generally undertaken by

the municipal body responsible for urban cleaning. Municipalities may provide these

services through their own resources, concessions to companies, outsourcing to

companies, or mixed systems such as rented vehicles and municipal labour.

It is recommended that solid waste from large generators (establishments that produce

more than 120 litres of waste a day) is collected by private companies, registered and

authorized by the municipality, without any cost to the public system.

Hotels and restaurants are examples of large solid waste generators in tourist cities.

Common domestic waste collection can be defined as the collection of refuse produced

in residential, public and commercial buildings, provided that the latter do not represent

large generators.

8.1.2 Collection regularity

Domestic waste collection services to each building should be regular, always on the

same days of the week and at the same times. When services are regular, citizens will

become accustomed to taking waste containers or bags out to the pavement in front

of their building a short time before the collection vehicle passes.

Consequently domestic waste is not left exposed in the street for more time than is

necessary, thus avoiding the presence of unsightly waste in the street and its scattering

by animals or people.

In tourist cities special attention should be paid to the amount of time that waste

remains in the street, due to the importance of aesthetics, unpleasant odour emissions

and the danger of attracting disease vectors and animals.

Regular collection is therefore one of the principal requirements for a good quality

service.

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In cities that have the means to weigh collected waste, the regularity of collections can

be mathematically verified by comparing the weight of waste over two or three

consecutive weeks. The weight of waste collected on the same day of each week (for

example the weight of the waste collected on a Monday compared with that of the

waste collected the following Monday) should not vary by more than 10%. Similarly, the

distance travelled by collection vehicles should be more or less constant on the same

day of different weeks as the itinerary of each particular day of the week is always the

same (with the same number of journeys to the waste destination point).

Collection irregularities are clearly indicated by accumulations of waste in the streets

and by the amounts of complaints received. The ideal for a domestic solid waste

collection system is therefore to establish fixed collection times and inform the entire

community of them through individual communications to the responsible person in

each building and even the posting of notices in the streets. The community will come

to trust the reliability of the collection service and will then cooperate by not discarding

waste in inappropriate places, by storing waste for collection in appropriate receptacles

and by putting it out in the appropriate place on the day and at the time stipulated, all

of which will contribute to increased environmental hygiene and public health, and the

cleanliness and improved appearance of the street.

8.1.3 Collection frequency

For climatic reasons, in most Latin American and Caribbean cities the interval between

domestic waste generation and its final disposal should be of no more than one week

in order to avoid bad odours and the proliferation of flies, rodents and other animals

attracted by the waste.

This situation is exacerbated in cities that use transfer stations (see chapter 9) as

waste is stored there for one or two days before being transported to the landfill

where it is finally covered with earth at the end of the day it arrives. If domestic waste

collection frequency is three times a week, the waste produced for example on a

Saturday may not be collected until the following Tuesday (three days later). If it is then

stored in the transfer station for two days and one more day is required for its burial

in the landfill, the total number of days between generation and final disposal can be

as many as six. Consequently, the minimum collection frequency recommended for

warm weather countries is three times a week.

Twice weekly collections, which are very common in suburban areas of Latin American

and Caribbean cities, should therefore be avoided. Budgetary restrictions represent

one of the main obstacles that municipal administrations face in their attempts to provide

sufficiently frequent services.

The capacity of households to store solid waste also has to be taken into consideration.

In informal settlements and other low income communities, houses do not have the


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Monday, Wednesday and Friday

Tuesday, Thursday and Saturday

¼ of the routes

¼ of the routes

¼ of the routes

¼ of the routes

Collection days First shift Second shift

capacity (due to limited space) to store waste for more than one day. The same problem

is faced in city centres where commercial and service provision establishments not

only have insufficient storage space but also produce a considerable amount of waste.

In all such cases daily waste collection is preferable.

8.1.4 Collection times

To significantly reduce costs and optimize the use of collection vehicle fleets, if possible,

collection should always be done in two shifts.

To obtain maximum performance the ideal usage of the collection fleet would be:

If for example, 24 collection routes are established, with a collection frequency of

three times a week, the number of collection vehicles required would be 24÷4= 6 (with

an additional reserve representing at least 10% of the operational fleet, in this example

one extra vehicle).

It is recommended that the day is divided into two 12 hours periods with one eight

hour working shift in each period. The first shift for example, could begin at 07.00 hrs

and the second at 19.00 hrs, so that there would be an interval for maintenance and

repair services between the two shifts.

In many Latin American and Caribbean cities the ideal of two waste collection shifts

per day is not possible due to the type of urbanization that exists in some

neighbourhoods where, for example, access streets are precarious and street lighting

is scarce, which can make a nocturnal collection shift impossible. The issue of urban

violence should also be considered here.

In streets and public areas where sweeping services are not frequent the cleanliness

of the collection operation is very important, that is, it is necessary to collect the

refuse put out for collection without leaving any refuse scattered in the street.

Whenever possible, sweeping should be done after a collection to remove any refuse

that may have been left scattered in the area.

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A team is the group of workers assigned to a collection vehicle toperform solid waste collection activities.

In central and commercial zones collection should take place at night when the circulation

of people and vehicles has diminished. In tourist cities collections should avoid the

hours of peak tourist activity in relevant locations.

The determination of collection times should also take into account the parking of

private vehicles in streets.

In purely residential neighbourhoods it is preferable that collection takes place during

the day but avoiding the times when there is more traffic on the principal roads.

During night time collections all necessary measures should be taken to reduce

noise. The collection team should be instructed not to raise their voices. The team

leader’s stop/start commands should be given through a switch at the back of the

truck connected to a light in the drivers cab. The truck’s engine should always be

well tuned and its silencer in good condition. In the case of a collection truck with

compaction facility the motor should not be revved up to accelerate the cycle of

compaction but should at all times have its automatic acceleration device functioning.

In the future more modern and silent vehicles may be needed, electric ones perhaps,

to respond to an ever more demanding general public, particularly in large urban

centres.

8.1.5 Restructuring domestic collection routes

Some of the factors that indicate a need for the restructuring of collection routes are:

increases or decreases in the population, changes in the characteristics of

neighbourhoods and an irregular collection service. Several elements should be taken

into account, such as:

Collection teams

In Latin American and Caribbean cities teams have from two to five members per

truck. Municipal teams tend to have more members than those of private companies

that provide collection services, reflecting the tendency for higher productivity with

private labour.

Equilibrium between routes

The tasks assigned to each collection team have to represent the same amount of

work, so that the physical effort required of the different teams is equivalent.


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In zones with high concentrations of waste collectors carry a lot of weight but

walk relatively short distances, whereas in zones with low concentrations of waste

they carry less weight but walk further. In both cases, the amount of calories

consumed can be approximately the same. The physical notion involved is that of

“work”:

work = force x distance

The restructuring method described here is one of the more simple ones and consists

of the division of the area to be restructured into “sub-areas” with a similar demographic

density and waste concentration (measured in kg/m). Each of these sub-areas can

then represent the same amount of work and working time. It should also be taken

into account that different workers have different physical constitutions and teams

should be balanced in this respect.

Collection route starting points

Routes should be laid out in such a way that teams begin at the point farthest from the

destination of the waste so that as they work they are diminishing the remaining distance

to be covered. The location of the fleet garage is another factor to be heeded in

planning.

Verification of the amount of domestic waste generated

It is important to verify the amount of solid waste that is generated in households,

public establishments and commercial premises, as this data is essential for an effective

restructuring of regular waste collection routes.

Although it is possible to calculate the per capita domestic waste generation rate through

the simplified method explained in chapter 5, ideally a more precise technical evaluation

of this parameter should be made, given the great variations between the different

zones of a city. Such variations could distort the dimensions of collection routes which

would then require considerable adjustment during the implementation phase of a

new collection program.

Data collection must include statistical data from high, medium and low income

neighbourhoods. Using data projection based on the latest available census, daily per

capita waste generation can be calculated.

As has already been mentioned, a certain technical rigour should be applied to the

determination of this rate as it can vary between 0.35kg and 1.00kg per person per day

in different areas of the city, depending on the socioeconomic stratum of the

inhabitants. In most small and medium-sized Latin American and Caribbean cities the

average per capita generation is between 0.50 and 0.80 kg/inhab/day (see chapter 5,

table 6 – Frequently used categories for determining per capita solid waste generation).

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Where for example the daily per capita solid waste generation is 0.70kg and the

population is 200,000, the weight of waste generated daily for collection will be:

200,000 inhabitants x 0.70kg/inhab/day = 140,000kg/day

This data is essential for calculating the required number of vehicles in the domestic

waste collection fleet.

The calculation of per capita waste generation can be done at the same time as studies

to determine solid waste characteristics.

In practice, the restructuring of collection routes can be more complex and involve

other variables that the planner has to take into account.

When the restructuring plans are ready the new routes can be used for two weeks,

after which problematic details can be adjusted.

Lack of a weighbridge to weigh waste

If there is no weighbridge to weigh truck loads of solid waste at its destination, an

alternative should be sought such as gaining access to the weighbridge of a company

or public body.

Should this prove impossible, a simplified approximate method, called cubing, can be

used to restructure collection routes on the basis of the volume of collected waste.

To calculate the amount of waste by cubing a standard receptacle of known capacity,

for example 100 litres, is used, and is repeatedly filled and emptied until all collected

waste has passed through it.

The number of times that the receptacle is emptied into the collection truck is counted

to determine how many times it is filled during a collection from one street block.

This method consists of:

! doing the cubing per block on the days of the week with more waste production, in

general Mondays and Tuesdays;

! writing down on a map the number of receptacles per street block; see example in

figure 20;

! progressively adding up the number of receptacles per street block, following the

itinerary of the route, until the truck is full, repeating this process for each trip in

each shift. In this way the total number of receptacles per trip and the number of

trips per shift, per vehicle can be determined;

! on pronounced slopes collections should be made beginning at the top and working

downwards to save the energy of the team and the fuel of the truck;

! test the new routes in practice, recording times, so that necessary adjustments can

be made.


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A street block is each one of the sides of a block in the city.

Figure 21 - Heuristic method collection route layout

Figure 20 - Example

Collection route layouts

Collection routes should be laid out in such a way that unproductive stretches are

minimized, that is those along which there is no waste to collect.

Routes should be designed through successive experimentation with a view to finding

the optimum one that at the same time responds to conditions such as the direction

of one-way streets, the avoidance of left turns in two-way streets and duplicated or

unproductive stretches. Collection route layouts tend to be arrived at through the

“heuristic” method, taking into account the direction of traffic, pronounced slopes

and ease of access and manoeuvre for the vehicles.

See figure 21 for an example of a rational collection route (heuristic method)

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I – Commercial sub-area

II – Predominantly residential sub-area

III – Hills sub-area

Figure 22

Sub-area II

Sub-area I

Sub-area III

* hours calculated in decimals

4,100

3,550

4,325

4,875

4,525

4,350

3,900

4,575

4,275

-

Workers perteam (4)

Routes

Rates

Kg/hr(2)/(3)

Current routes – Mondays and Tuesdays

Table 13

Kg/m**(2)/(1)

Kg/Worker(2)/(4)

1.15

1.08

1.18

1.19

1.20

0.96

1.12

1.17

1.13

-

2,000

1,839

1,977

2,169

1,851

2,012

1,667

1,828

1,915

-

Averagetime ofwork

hrs* (3)

4

4

4

4

4

4

4

4

4

-

8.20

7.72

8.75

8.99

9.78

8.65

9.36

10.01

8.93

-

Weightof wasteKg (2)

16,400

14,200

17,300

19,500

18,100

17,400

15,600

18,300

17,100

153,900

Length ofroutem (1)

14,250

13,180

14,600

16,410

15,120

18,040

13,870

15,660

15,141

-

01

02

03

04

05

06

07

08

Averages

Totals

** kg/m = waste concentration

Collection route restructuring method

This method consists of:

! dividing the city in sub-areas;

! surveying and systematizing the characteristics of each route;

! analyzing the collected data;

! restructuring routes based on:

! the elimination (or minimization) of overtime;

! the new weight of waste for collection per shift;

! the concentration of waste in each area.

A city where the collection routes need to be restructured has to be divided into sub-

areas of similar demographic density, for example, sub-areas I, II and III. Let us suppose

that in sub-area II there are currently eight collection routes, covered in two shifts

three times a week by two compaction vehicles. The data for the current program can

be seen in table 13.


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With a normal work shift of 8 hours, it can be seen that the time used to complete the

routes is too much and therefore requires overtime (based on the supposition that

the collection is done regularly).

If the objective is to finish the collection in eight hours and thus avoid overtime, the

weight to be collected per working shift can be calculated assuming no change in the

productivity of collectors.

W = kg/h x Ts

Where Ts is the duration of the work shift (8hours in this case). Therefore:

W01 = 2,000 x 8 = 16,000kg W05 = 1,851 x 8 = 14,808kg

W02 = 1,839 x 8 = 14,712kg W06 = 2,012 x 8 = 16,096kg

W03 = 1,977 x 8 = 15,816kg W07 = 1,667 x 8 = 13,336kg

W04 = 2,169 x 8 = 17,352kg W08 = 1,828 x 8 = 14,624kg

Total weight 112,744kg

Average weight 15,343kg

As the weight that can be collected in an eight hour work shift is 15,343kg, uncollected

waste would amount to:

153,900kg – 112,744kg = 31,156kg

As the average collection weight for new routes would be approximately 15,343kg/

route, it will be necessary to initiate:

31,156kg ÷ 15,343kg = 2.03 new routes

That is, in practice two routes more, one on Mondays, Wednesdays and Fridays and the

other on Tuesdays, Thursdays and Saturdays.

As in future the area will be covered by 10 routes, the average weight per route will be:

153,900kg ÷ 10 routes = 15,390kg/future route

Future routes should be marked on the map taking into account the concentration of

waste in each area (expressed in kg/m).

To achieve this, the length of each route is multiplied by the waste concentration until

obtaining an approximate weight of 15,390kg/route, applying the formula:

L x C = W

Where:

L = length of route (m)

C = waste concentration (kg/m)

W = average weight of future routes (kg)

100

In the example, the average weight of the future routes will be approximately 15,390kg.

The number of vehicles will be: number of routes ÷ 4 = 2.5

So, three vehicles can be used during the first shift and two during the second. The

type and capacity of the vehicles depend on the number of journeys that are necessary

to the final disposal site. For example, if on Mondays and Tuesdays two journeys are

necessary, the average load per journey would be 15,390kg ÷ 2 = 7,695kg.

When it is raining the weight of waste increases by 20%. Fluctuations in the number of

tourists also have to be taken into account as they cause increases or decreases in

waste production.

8.1.6 Collection vehicles

There are two types of specialized vehicle in general use for domestic waste collection

and transport:

! compactors – rear loader or side loader;

! without compaction – with the box closed by sliding doors.

Particularly in smaller cities with limited budgetary resources conventional open dump

trucks are frequently used as well as other equipment described later.

A good domestic waste collection vehicle should have the following characteristics:

! that it does not spill waste or leachate on the street;

! a compaction rate of at least 3:1, that is 3m³ are reduced by compaction to 1m³;

! a waist high loading height of no more than 1.20m from the floor;

! the possibility of emptying at least two receptacles at the same time;

! rear loading (preferably);

! adequate space for transporting the team;

! fast unloading of waste at its destination;

! a loading compartment capacity of at least 1.5m³;

! good manoeuvrability and potency for steep inclines;

! lifting devices to empty different types of containers;

! even load distribution on the truck’s chassis;

! adequate carrying capacity to minimize the number of journeys to the waste

destination while at the same time being appropriate for the characteristics of the

operational area.


101

Figure 23 - Containers being emptied into a compaction truck

Solid waste collection operations involve dangers for the collection personnel. Every

time the vehicle stops the team is exposed to the risk of injury through other vehicles

colliding with the rear of the collection truck.

The risk of being run over is high and efficient preventative measures must always

be taken.

In compactor vehicles it is essential to always take precautions with the compaction

mechanism. In addition adequate space should always be available on the truck for the

collection team.

Therefore, the most recommendable technical solution is to use compactor collection

vehicles wherever possible. However, due to the characteristics of a particular urban

area, sometimes this is not an option for operational or economic reasons.

In such cases the most cost efficient type of vehicle and equipment should be selected.

The vehicle that is chosen should be the one with more of the above listed

characteristics while taking into account the particular conditions of the service

provision area (the condition of the streets, topography, manoeuvring conditions, etc.).

Some vehicles and equipment in general use for domestic waste collection are described

below.

102

Total gross weight (TGW) = chassis weight + box weight + load weight.

Figure 24 - Closed box truck

Closed box collection trucks

A solid waste collection vehicle without compaction, appropriate for working in small

communities with a low demographic density. It can also be used in areas with

pronounced inclines. The box volume can vary from 4 to 12m³ corresponding to a

truck total gross weight (TGW) of from 7 to 12 tons.

Unloading is by hydraulic box tipping. This truck represents a low cost option in terms

of both purchase and maintenance but has quite a low productivity. It requires great

physical effort from the collection team who have to lift the waste up to the edge of

the box, which is more than two metres high, much higher than the compactor collector

loading compartment height of approximately one metre.

Compactor collection trucks

Solid waste compactor collection trucks, which are usually rear loaders but can be side

loaders, are made of steel and have a capacity of 6, 10, 12, 15 or 19m³ corresponding

to a truck TGWs of 9, 12, 14, 16 and 23 tons respectively. They may have hydraulic

devices for the automatic and independent unloading of standardized containers.

This type of vehicle is used for domestic, public and commercial waste collection,

especially in zones where there are high concentrations of solid waste from large

generators or a high demographic density. Its use can be limited by unfavourable road

conditions such as irregular layouts, unpaved and potholed surfaces, or roads unsuitable

for heavy vehicles.


103

Figure 25 - Side loader compactor collection truck – 6m³

Figure 26 - Rear loader compactor collection truck – 10 to 15m³

Figure 27 - Rear loader compactor collection truck – 19m³

Dumpster carrier trucks for 5m³ stationary containers

Domestic waste collection systems that employ 5m³ stationary containers replaced by

dumpster carrier trucks with multifunctional crane are appropriate for zones with low

quality houses or difficult access. Containers are located at strategic points close to

104

Figure 28 - Compactor container

the communities they serve but with easy access for the dumpster carrier trucks that

replace loaded containers with empty ones.

There are two types of dumpster carrier truck with differing operational capacity:

! single - that transport only one 5m³ stationary container at a time;

! double - that can transport two 5m³ stationary containers at the same time.

Stationary compactor (compaction container) collection trucks

For the collection of large volumes of domestic waste special stationary metal containers

incorporating a compaction device can be used. These containers are called stationary

compactors, in general have capacity for 7 to 20m³ of loose waste and are transported

on special vehicles. The 7m³ capacity stationary compactors can be transported by

dumpster carrier trucks with multifunctional crane, while those with greater capacity

are transported by roll-on / roll-off trucks.

In big cities this system is slowly replacing the system of open stationary containers

transported by dumpster carrier trucks with multifunctional crane because, being more

hermetic and having a greater waste storage capacity, compaction containers offer

aesthetic, sanitary and economic advantages.

Traditional dump truck type collection vehicles

These open box vehicles without a compaction device and not specifically designed

for domestic solid waste collection are frequently used in small communities with a

low demographic density and in areas of rough topography where it is difficult to

manoeuvre bigger compactor trucks. As with closed box collection trucks, unloading is

by tipping the box, the volume of which can vary from 4 to 12 m³ in trucks that

correspondingly vary from 7 to 12 tons TGW.


105

Figure 29 - Dump truck with crane moving a special “Molok” container

This type of vehicle is attractive for small municipalities due to its operational flexibility.

It can be used for various different activities, not only waste collection, and is therefore

appropriate for small cities where, due to the low level of waste production, a

specialized vehicle would be unused for significant periods of time. Another advantage

is its low purchase and maintenance costs.

The main disadvantage for domestic waste collection is that the box is open and it is

therefore difficult to keep the load inside it (particularly lighter waste) and avoid it

being scattered by the wind along the route. In order to minimize this problem, canvas

or plastic sheeting can be used but in practice the efficiency of this is questionable as

it significantly reduces the productivity of the collection team. Productivity is also

negatively affected by the loading height of the box and this too should be considered.

Special solid waste storage systems serviced by dump trucks equipped with a hydraulic

crane are now available on the market. Amongst them is the “Molok” system that can

be considered as an option in special situations, including in informal settlements, due

to its operational, aesthetic and sanitary advantages when compared with other more

conventional systems. However it is necessary to carry out a viability study before

implementing this system as it requires significant initial investment for purchasing the

containers, plastic bags, etc. Figure 29 shows this system in operation.

8.1.7 Tools and implements used by collectors

It is important that collection teams collect domestic waste without leaving any of

it scattered around. For this purpose medium-sized sweeper brooms and shovels

should be used.

106

Figure 30 - Sweeper cart, wheelbarrow and wheelie bin

A medium sized sweeper broom has a wooden base with 22 holes into which natural

fibres or recycled plastic bristles are fixed. These days the latter are increasingly

being used.

8.2 Public solid waste collection and transport

8.2.1 Concept

Public solid waste collection includes the collection and transport of waste gathered

as a result of routine and emergency street cleaning activities, such as sweeping,

weeding, pruning and special waste collection (for example waste and mud deposited

in the street by flooding).

The method, vehicles and equipment to be used in collection depend on the specific

nature of each individual cleaning operation, the type of waste generated and the

form of storage.

There are three basic categories that determine the collection method for public waste:

! loose waste accumulated on the ground;

! waste packed in plastic bags;

! waste stored in wheelie bins or dumpsters.

Differences in specific weight and other physical characteristics of waste demand

different solutions for loading (manual or mechanical) and transport to a transfer station

or final disposal unit.

8.2.2 Collection of waste gathered by sweeping

Waste collected by street sweeping can be transported by the sweepers while

performing the service, for which purpose hand carts made of steel tubing with a

metal container (sweeper cart), wheelie bins or, on pronounced inclines, wheelbarrows

may be used.


107

In all cases it is recommendable that waste, which mostly comprises light material that

can be easily scattered by the wind, is stored in plastic bags for collection.

They can then be collected by compactor trucks (rear loaders or side loaders), which

are especially appropriate in large cities due to the high productivity of this type of

vehicle and the large volume of waste to be collected. The collection of this type of

waste at the same time as domestic solid waste represents an important device for

rationalizing collection and transport costs. Vehicles without compaction devices can

also be used: closed box trucks, traditional dump trucks or dumpster carrier trucks

that can handle stationary containers.

Because sweeping is undertaken in the more urbanized zones of the city it is important

to carefully plan the collection of this type of waste so that it remains on the street

for the minimum possible time, bearing in mind that a slower collection process could

adversely affect the municipal administration’s image of efficiency. As sweeping has

to be done in each zone as a programmed routine on pre-established days and at

specified times, it is completely feasible to integrate it with collection.

To determine the quantity of waste collected by street sweeping, it is necessary to do

a field survey in order to identify the average generation per sweeping route and, on

that basis, calculate the production of each sector. The generation of waste collected

by sweeping is influenced by various factors such as the predominant usage of the

street or public space, the level of environmental education of passers by, the type

and state of the surfacing on the street and pavement, as well as the characteristics of

any trees.

Depending on the type of trees, the generation of street waste can increase

considerably due to seasonal factors, that is, the falling of leaves and fruit onto

pavements and streets.

8.2.3 Collection of waste from weeding and vegetation cutting

Weeding and vegetation cutting activities generate vegetation waste that usually

accumulates in piles along the section of a street where the work has taken place.

From there it is carried by hand to the box of the collection truck (generally a

conventional dump truck).

An operational alternative that is sometimes adopted is to locate an open stationary

container near to the area where the work is taking place so that waste can be deposited

in it as the work advances. Such containers are subsequently removed by dumpster

carrier trucks with multifunctional crane.

When the dimensions of collection and transport services are being determined the

low specific weight of this type of waste should be taken into account as it results in

the load capacity of the collection truck being under used. The integration of this

waste’s collection with the collection of soil and sands that have accumulated on the

streets is an option for utilizing the truck’s full load capacity.

108

The identification of nearby locations appropriate for the disposal of this waste, eroded

areas for example, can also reduce the cost of transport, but appropriate sanitary and

environmental care should always be taken in disposing of it.

The necessary dimensions of the collection fleet are assessed by experienced operators

during a pre-operational visit to the site on which weeding and land clearing services

will be undertaken.

8.2.4 Tree pruning waste collection

Tree pruning is often linked with the municipal urban cleaning sector. Due to the nature

of this activity it usually requires the support of a truck to transport tools, implements

and labour. It is therefore often natural that the same truck is used to collect the

waste generated as work progresses.

This type of waste includes loose leaves, small branches and thick trunks, and its

physical characteristics mean that when it is loaded into the box of the truck many

spaces are left unoccupied. Due to this low specific weight, the collection and transport

operation is relatively expensive and involves low productivity.

As with the disposal of weeding and land clearing waste, disposal sites that are near to

the generation site can be sought for pruning waste. The load can be prepared for

collection at the generation site using standard pruning tools (machetes, saws and

chain saws) to make the material more homogeneous and to prepare part of the waste

for reuse (the thicker trunks, for example).

Recently new technological alternatives have been incorporated in pruning

operations to address the low productivity and high cost of collection and transport

in cities that produce large amounts of such waste. A branch grinder can be an

important component of an economical and environmentally sound operational

solution to this problem. This is a robust and compact machine, available in towable

models, that can reduce by up to ten times the volume of a pruning waste load.

Another advantage of this system is that the ground waste is easy to dispose of in

appropriate nearby locations as the final product has a low granulometry and can

be used as coverage for natural soil, minimizing erosion risks and incorporating

organic matter.

Pruning operations tend to use a fixed box truck with a special elevation platform to

raise the worker for the cutting of higher tree branches.


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8.2.5 Collection of rubble and other construction waste

This type of service can be provided directly by the public administration or by

authorized private companies. In the latter case previous authorization is needed so

that the identity of service providers is known and their activities can be overseen on

an ongoing basis in order to prevent the clandestine disposal of waste in inappropriate

places.

Basically there are two types of situation that require rubble collection services:

! where rubble has been clandestinely disposed of in the street, on wastelands or on

the banks of bodies of water;

! where generators of this type of waste request or contract services.

In the first case it is clearly the responsibility of the public administration to collect

construction rubble that has been indiscriminately disposed of in the city, a responsibility

that requires the urban cleaning body to maintain the necessary infrastructure for this

purpose. Where requests for collection are made by generators it is recommended

that this service is provided by the municipal urban cleaning system only to small volume

generators (there should be a specific municipal regulation on this subject). Where

construction works produce larger amounts of rubble the “polluter pays” principle

should be applied.

Whoever provides the service it should be scheduled, with the cooperation of the

generator, for the day and time most appropriate for waste collection taking into ac-

count factors such as the traffic flow and parking conditions in the street closest to

the place of generation. Service provision should be organized not only to coordinate

requests that have been granted and to incorporate field survey data, but also to

ensure a rational route that minimizes unproductive journeys and maximizes opera-

tional productivity.

Construction rubble collection is in general undertaken by conventional dump trucks

or 5m³ stationary containers transported by dumpster carrier trucks with multifunc-

tional crane.

8.2.6 Special collections

This type of service is necessary in certain situations, which regrettably are common in

Latin American and Caribbean cities, where inappropriate waste accumulation sites or

clandestine rubbish dumps arise, generally located on wasteland or unoccupied plots.

The expression “rubbish attracts more rubbish” summarizes the underlying causes of

this type of accumulation: small volumes of pruning waste for example are left in a

particular place, this may then be added to by other people disposing of construction

rubble there. Subsequently local residents add plastic bags of residential waste and in

a short time there is a large accumulation of waste that causes serious sanitary and

environmental impacts.

110

Figure 31 - Dumpster carrier truck with multifunctional crane

In general the existence of waste accumulation sites and clandestine refuse dumps

results from operational defects in the regular domestic waste collection and street

cleaning system together with deficiencies in the supervision of municipal activities.

The lack of attention to these issues by those responsible for urban cleaning means

that the causes of this serious problem are not addressed but only its consequences,

and thus new cases repeatedly arise necessitating more and more special collection

services.

Due to the large amount of waste that accumulates on such sites, collection

operations may require mechanical loading equipment (mechanical loader), rather

than a manual operation, and large vehicles for collection and transport to the final

disposal site.

8.2.7 Vehicles and equipment used for collection

Dumpster carrier trucks with multifunctional crane for handling 7 ton containers

A truck (minimum total gross weight 13.5 tons) with a mounted minimum 7 ton capacity

hydraulic crane for lifting and transporting open metal containers loaded with solid

waste. These trucks can be single carriers to transport one container at a time or

double carriers to transport two containers at a time.

To be productive they have to operate over short distances between container

locations and the unloading site.


111

Figure 32 - Short dump truck

Figure 33 - Long dump truck

Short dump truck

A two axle vehicle for the collection of public waste, construction rubble and earth

with a box of 5 to 8m³ capacity with a respective truck TGW of from 12 to 16 tons.

Long dump truck

A three axle vehicle for the collection of public waste, construction rubble and earth.

The box generally has a 12m³ capacity and the truck a TGW of 23 tons.

This truck is usually loaded by a mechanical loader to reduce human effort and increase

productivity.

Roll-on / roll-off container carrier truck

A collection truck with devices for lifting 10 to 30m³ stationary containers without a

compaction device (figure 16). Each vehicle should handle six containers for its

productivity to justify its use.

These three axle trucks should have a TGW of 23 tons.

112

Figure 34 - Semi-trailer

Figure 35 - Mechanical loader

Semi-trailer

A semi-trailer dumper with capacity of 25m³ pulled by a 4x2 truck with a 45 ton pulling

capacity. It can be used to transport rubble or in support of large earth or mud collection

operations. It is loaded by mechanical loader and is unloaded at the final destination by

box tipping.

A semi-trailer is a trailer the front part of which has to be supported on a towing

vehicle called a semi-trailer truck.

A canvas or plastic sheet should cover the top of the box to avoid waste being scattered

in the road by the wind while the vehicle is moving.

Mechanical loader

A wheeled tractor loader used to pile up earth, rubble, mud and waste, and to load

dump trucks, dumper boxes and semi-trailers in street cleaning operations and at waste

accumulation sites.

For street operations machines with a scoop capacity of 1,5m³ are normally used,

while for loading semi-trailers it is advisable to use machines with a 3m³ scoop to

increase productivity and because of the higher loading level.


113

8.3 Waste collection in tourist cities

The amount of waste to be collected varies according to tourist season related

population fluctuations as well as the usual all year round fluctuations.

As the usual fluctuations (weekly and monthly) have little effect on the size of the

fleet that is needed, this section will deal with the necessary procedures for maintaining

the quality of domestic waste collection in tourist cities during the season of population

influx.

The basic measures to take are:

! the introduction of overtime for collection workers, within the limits imposed by

employment legislation;

! an increase in the number of collection shifts;

! the utilization of the reserve fleet in operations;

! the contracting of extra vehicles from private companies or individuals.

Whenever possible the contracting of extra vehicles should be planned in advance to

avoid overpricing.

It is important to note that these measures should be taken in sequence in order to

limit the increase in collection costs to a minimum.

Other important factors to take into account are:

Traffic

In tourist cities the traffic is usually congested during holiday periods, which impedes

the movement of collection vehicles and increases the time taken to cover collection

routes. Waste collection schedules should therefore be set for times when traffic is

less heavy.

Beaches

In coastal cities where tourists tend to concentrate around the beaches, collection

routes that cover streets bordering the sea should be revised and restructured in

order to adapt them to seasonal requirements, not only in regard to the increased

amount of waste but also the frequency and times of collection.

A reduction in the frequency of collections should never be considered, even though

it may be attractive for economic reasons, as the longer the interval between

collections the greater the danger of waste accumulation sites appearing in the streets,

which are detrimental to the city’s sanitary and environmental condition and discourage

tourists.

114

Figure 37 - Micro tractor and dump trailer

Figure 36 - Micro tractor

8.4 Solid waste collection in informal settlements

There are informal settlements in many Latin American and Caribbean cities due to the

poor socioeconomic conditions experienced by a significant sector of the population

in the region.

A lack of basic urban infrastructure in these communities causes significant obstacles

for the provision of domestic waste collection services:

! difficult access for conventional collection trucks;

! inadequate or nonexistent preparation and pre-collection storage of waste;

! the tendency of inhabitants to discard waste immediately after generation as there

is minimal space inside the houses.

These factors have to be taken into account in planning alternative waste collection

systems in these communities with a view to improving a situation that presents serious

risks to public health and the environment.

One solution to the problem of access through narrow internal streets, often with a

pronounced incline, is the use of special vehicles that are narrow, have good

manoeuvrability and the capacity to deal with steep slopes.

Mini-tractors or agricultural tractors with 4x2 or 4x4 drive towing 2,5m³ capacity trailers

with metal or wooden boxes are feasible alternatives.

(4x2) – two axle vehicle with rear wheel drive.

(4x4) – two axle vehicle with four wheel drive.


115

As these vehicles are not appropriate for long journeys, the collected waste is

transported to a temporary storage place where it is kept for subsequent transport

to a final disposal site. It is normally recommended that stationary containers are

used for this temporary storage and they are then either transported by special

collection vehicles (dumpster carrier trucks) or emptied into large compactor trucks.

When installing open containers in informal settlements it is necessary to take the

precautions already mentioned in chapter 7 in order to avoid a prejudicial proliferation

of insects and animals. If appropriately clean conditions and supervision are not

maintained there is a risk of people setting fire to the waste.

The problem of pre-collection waste storage in these areas can be dealt with by siting

containers along the micro tractor collection route, preferably plastic containers with

lid and wheels.

The frequency of collections should be carefully considered and ideally there should

be only short intervals between them, daily collection being the best option.

It has to be pointed out that in many of these communities it is not even possible to

use the mini-tractors for collection due to a lack of passable access. In such cases

collection should be manual, with the waste being carried to some point that is accessible

for some type of vehicle.

In several cities the contracting of community collectors has produced good results. In

these cases, the municipality contracts the community centre, for example, which then

selects the people who will work in the collection team (as well as carrying out weeding

and channel cleaning tasks, etc.).

It is worth noting that contracting community collectors involves the principle of

community participation as it encourages other residents to participate in the

maintenance of the place where they are living as they may feel an obligation to keep

public areas clean when it is one of their neighbours who is doing this work.

8.5 Collection of medical waste

8.5.1 Acknowledgement of the problem

Hygienic conditions in health service establishments (hospitals, clinics, medical centres,

veterinary clinics, etc.) are fundamental for the prevention of infections. Regular cleaning

with germicide solutions keeps floors, walls, roofs and furniture free of dust, body

fluids and any waste from medical activities. Appropriate internal transport and storage

together with subsequent collection and external transport of waste complete the

measures aimed at reducing infections.

116

In hospitals medical waste generation rates are related to the number of beds. Table

14 shows waste generation per bed in some countries and in Rio de Janeiro city.

Medical waste is classified as common, infectious or special (see table 4).

Hospital areas are classified in three categories:

! critical areas: where there is a greater risk of infection such as operating theatres,

delivery rooms, infectious disease isolation rooms, laboratories, etc.

! semi-critical areas: where the risk of contamination is less, such as the rooms occupied

by patients with non-infectious diseases, nurses’ rooms, laundries, refectories and

kitchen areas etc.

! non-critical areas: where in theory there is no risk of infection, such as administration

rooms, storerooms, etc.

8.5.2 Segregation

There are regulations that must be followed for the segregation of infectious and

common waste in health service establishments:

! at the time of its generation all infectious waste should be put in a receptacle close

to the place where it is produced;

! infectious waste must be stored in accordance with stipulated technical standards,

in well closed plastic bags (generally coloured cream);

! puncturing and sharp waste (needles, glass, etc.) should be stored in special

receptacles specifically for this purpose;

Table 14

Place

Medical solid waste generation rates

0.97 – 1.21

3.10

1.85 – 3.65

2.93

3.80

2.63

3.98

Chile

Venezuela

Argentina

Peru

Paraguay

Brazil

Rio de Janeiro

Average generation kg/bed/day


117

! waste from clinical analysis, blood transfusion therapy and microbiological research

should be sterilized in the place of generation;

! infectious waste consisting of human body parts, organs and tissues should be

separately put in cream plastic bags that are then appropriately closed.

8.5.3 Separate collection of common,infectious and special waste

Infectious and special waste should be separated from common waste before collection.

Radioactive waste should be dealt with in accordance with each country’s specific

regulations issued by the respective governing body.

Infectious waste and the rest of the special waste should be stored in cream plastic

bags which are put into standardized containers that are mechanically emptied into

special vehicles for medical waste collection. This waste represents at the most 30%

of the total medical waste generated.

If there is no separation of infectious and special waste all of the waste should be

packaged, stored, collected and disposed of as though it is infectious or special waste.

Current norms recommend that in most cases medical waste is collected daily, even on

Sundays.

8.5.4 Vehicles for collection and transport

As plastic bags with infectious or non-separated waste can break and release

contaminated liquids or air, collection vehicles should not have compaction systems

and, as an additional precautionary measure, must be hermetic and have liquid capturing

devices. Depending on their size they should have mechanical devices for both empting

the containers and unloading the vehicle.

Common waste generated in these establishments should be collected by the normal

collection service.

The types of vehicle usually recommended for medical waste collection are presented

below.

Van

A light van with the driver and passenger cab independent from the load compartment

and a load capacity of 500 kilos. The load compartment should be lined with fibre glass

in order to avoid the accumulation of infectious waste at the edges and in cracks and

to facilitate washing and cleaning.

Light vans with hermetic load compartments and a capacity for approximately 2m³ of

waste, are suitable for the collection of puncturing and sharp objects from chemists,

analysis laboratories, dental clinics and other similar establishments. In some cases it

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Figure 38 - Van for medical waste collection

Figure 39 - Truck for infectious waste collection

may be economical for these vans to unload waste that they have collected in the

loading areas of bigger medical waste collection vehicles, which will then transport it

to the final disposal site.

Truck for infectious waste collection

A two axle collection truck with a capacity of 6 to 8m³, without a compaction device.

A tipping system may be incorporated for the emptying of plastic or metal containers

with a capacity of up to 700 litres. The box is made of steel with continuous welded

seams to avoid liquid leakage and has a compartment for capturing liquid originating

from the load with a device for unloading it in an appropriate place. The rear door of

the load box must close with an efficient seal. The unloading of waste is done

through the tipping of the load box after the rear door has been fully opened. The

hydraulic powered system is coupled with the gearbox and is pneumatically operated

from inside the cab. Amongst the chassis recommended are: VW 8150, MB 914 and

Ford Cargo 81.


119

To achieve good quality medical waste management it is important toinstigate educational processes that prepare people for change.

8.5.5 Aspects of collection planning

When planning the collection of this type of waste a determination should be made,

together with the generators and the responsible health authority, of the amount of

waste generated in each establishment and the possibilities for treating it at source,

while at the same time establishing appropriate methods for its pre-collection

preparation and internal storage.

The steps to follow include:

! locate on a map all health establishments: hospitals, out-patient departments,

chemists, medical centres, emergency services and clinics;

! based on collected data, determine the necessary type, size and number of collection

vehicles, the frequency of collections and collection routes;

! select van type collection vehicles with leak-proof load compartments and liquid

retention trays;

! train the service operation teams, including in measures for their own protection

and work safety practices.

The basic guidelines for rationalizing costs and establishing an appropriate service

management policy are the following:

! facilitate treatment;

! prevent contamination;

! intensify safety measures;

! avoid work accidents;

! maintain an organized and pleasant work environment;

! acknowledge employees’ work;

! reduce absenteeism.

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Solid waste transfer9

9. Solid waste transfer

121

Transfer stations are units sited close to areas of large-scale wastegeneration so that collection trucks can unload there and return

rapidly to continue their collection route.

9.1 Concept

At the same time as large and medium-sized cities have experienced intense urban

expansion there has been an increase in both environmental pressures and the

resistance of residents to accepting the installation close to their homes of facilities

related with solid waste final disposal. In addition urban land is too expensive to be

used for sanitary landfills, for which large areas are required. Consequently final disposal

sites are being established further and further away from centres of large-scale waste

generation. This increased distance between collection areas and sanitary landfills

creates the following problems:

! delays in completing collection routes thus prolonging the time that waste is exposed

on the street;

! increased unproductive time that collection teams spend waiting for the return of

the truck from unloading at the landfill;

! increased transport costs;

! reduced productivity of collection trucks, which are specialized and therefore

expensive vehicles.

To solve these problems some municipalities are establishing transfer stations.

Waste unloaded in transfer stations is transported to the sanitary landfill by a larger

vehicle that involves lower transport cost per unit.

Vehicles used for transporting waste from transfer stations to final disposal sites

usually have three times more load capacity than collection trucks.

In general transfer stations begin to be considered when the distance between

the location of large-scale collection activities and the sanitary landfill is greater

than 25km. In large cities where traffic conditions make travel very slow, transfer

stations are sometimes used even when the distance to the sanitary landfill is

shorter.

The establishment of a transfer station should be preceded by a feasibility study that

evaluates the economic and operational advantages that it could provide to the collection

system.

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Figure 40 – Direct transfer station

Modes of transport from transfer stations can be:

Train – suitable for long distances or for cities where traffic on roads to the final

disposal site is too congested. This requires a complementary system of trucks to

transport waste from the unloading site to the sanitary landfill.

Boat – suitable for long distances and an excellent option in cities that have navigable

rivers or bays. Ideally waste should be transported in closed containers to avoid

scattering.

A complementary system of trucks is required to transport waste from the unloading

site to the sanitary landfill.

Truck – the most used system, recommended for transporting over medium distances

and in places where the traffic on roads to the final disposal site is not too congested.

9.2 Types of transfer station

9.2.1 Direct transfer station

This is a commonly used type of transfer station. It has a drop between the unloading

platform and the loading area, so that a collection truck on the higher level unloads

directly into the transfer truck below.

As there is no space for waste storage in these stations, a larger fleet of transfer

vehicles is required to avoid collection trucks having to wait too long to unload.

9.2.2 Station with storage facilities

In most cities all collection trucks begin their routes at the same time and so it is

probable that the vehicles become full and arrive at the transfer station within the

same timeframe. The simultaneous arrival of vehicles makes it indispensable that the

station has an appropriate place for the storage of waste to deal with unloading “peaks”.

Waste storage also facilitates the operation of the system with fewer vehicles. Amongst

the more commonly used models for transfer stations with storage facilities are:


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Figure 41 - Transfer station with storage and compaction

Figure 42 – Station with storage without compaction

Station with silo storage and compaction

The main objective of these stations is to increase the specific mass of waste in order

to reduce transport costs. The traditional model has a storage silo and a drop between

loading and unloading platforms. A hydraulic system installed in the silo compacts waste

inside the transfer vehicles.

When this equipment is used weight specifications for the transfer trucks must be

observed so that loads do not surpass the legal limits.

Station with silo storage without compaction

Some units have storage silos to receive waste brought by collection trucks. Hydraulic

digger type machines load waste from the silos into transfer vehicles. This model is

more appropriate for stations that receive a maximum of 1,000 tons per day as in

larger units it would imply excessive construction costs.

Station with floor storage without compaction

Another model commonly used is that of floor storage stations. These stations have

covered paved floors with closed sides to avoid the exposure of waste to the elements

and improve the aesthetics of the establishment. The loading of transfer vehicles is

done by hydraulic diggers or mechanical loaders. This model facilitates the fast unloading

of collection trucks and loading of transfer vehicles, and can be used in small or large

stations.

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Figure 43 – A 45m³ semi-trailer tipper

9.2.3 Alternative transfer systems

The transfer station concept, although originally developed to respond to the needs

of large cities, can be incorporated on a smaller scale in special situations in small

communities where access is not possible for conventional collection vehicles. For

example, an alternative collection system using carts pulled by animals to cover

streets that are not accessible to collection trucks, may involve the unloading of

collected solid waste in a stationary container (or equivalent receptacle) at a site

where larger vehicles do have access and can collect the waste and transport it to

its final destination.

9.3 Vehicles and machines for transfer stations

To transport waste unloaded in transfer stations large interchangeable tipper containers

can be used, manoeuvred by vehicles equipped with cranes to lift them onto and off

platforms, or semi-trailers with or without compaction.

The models most used in transfer stations are: semi-trailer tippers and semi-trailers

with movable floor.

Semi-trailer tippers

A semi-trailer tipper towed by a 4x2 semi-trailer truck with a 45 ton pulling capacity. It is

loaded from a transfer ramp or by a mechanical loader or hydraulic digger, and unloaded

by tipping. The model most commonly used has a capacity of 45m³.


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Figure 44 - A 70m³ semi-trailer with movable floor

Semi-trailer with movable floor

A semi-trailer with a capacity of 70m³, towed by a 4x2 semi-trailer truck with a 45 ton

pulling capacity. It is loaded from a transfer ramp or by a mechanical loader or hydraulic

digger, and unloaded by the alternating movement of the movable floor’s strips.

In all open semi-trailers the load should be covered with plastic sheeting or a net to

avoid waste falling in the roads.

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Street cleaning10

10. Street cleaning

127

10.1 The importance of street cleanliness

Up to the mid-19th century there was not only refuse in city streets but also the

remains of food and large amounts of animal and human excrement. The filthy conditions

in Europe during the Middle Ages are well documented, as are the plagues and epidemics

that they produced.

However, in several cities of the world for many centuries there have been laws and

municipal regulations prohibiting the discarding of waste and objects in the streets.

As a result of developments in medicine and sanitary engineering during the 19th century,

it was recognized for the first time that human waste not collected, treated and

appropriately disposed of is a significant source of disease and can provoke fast

spreading epidemics. The relationship between waste dumped in the street, the rats,

flies and cockroaches attracted by it and the transmission of diseases through those

vectors was also discovered. It was then that effective measures began to be taken

for the collection of domestic waste rather than allowing it to be thrown onto streets

or wasteland.

Flies and rats that proliferate in rubbish can transmit many diseases. They are called

disease “vectors”.

Most animal excrement (except for dog excrement) was eliminated from the streets

with the advent of motorized transport that replaced animal driven carts.

The surfacing of streets and the dissemination of hygiene and public health principles

in schools also contributed to the reduction of waste in the streets.

Keeping streets clean is important for the community and the collective interest must

be given priority over individual interests in order to respect the wishes of most citizens.

The principal motives for keeping streets clean are:

Sanitary

! to prevent diseases caused by vector proliferation in waste accumulations on the

street or on wasteland;

! to avoid damage to health caused by dust coming into contact with eyes, ears, nose

and throat.

Safety

! to avoid damage to vehicles from branches and sharp objects;

! to promote road safety by eliminating dust and earth that can cause skidding and

dry leaves and grass that can cause fires;

! to avoid rain water drainage systems becoming clogged up.

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Aesthetic

! a clean city inspires pride in its inhabitants, improves the appearance of a place,

helps to attract new residents and tourists, increases the value of property and

stimulates business.

The aesthetic aspect of street cleanliness forms a significant part of arguments for

the implementation of policies and measures to improve the image of cities, particularly

so in tourist cities. Whatever the historical significance, landscape beauty or cultural

richness of a city, in the context of tourism it is hard for a visitor to leave with a

positive impression when a place is aesthetically ugly due to a lack of cleanliness.

While it is true that a tourist demands cleanliness of a city, it should also be noted that

he himself is in many cases contributing to its dirtiness.

In general the tourist does not establish an attachment with the place he is visiting, he

is a mere visitor, a consumer of space. Consequently his consideration for the place is

less intense than that of residents. In general people take more care of their own

houses than of spaces that do not belong to them.

In view of these attitudes, it is important that tourist city municipalities implement urban

cleaning education campaigns specifically addressed to visitors, with a view to maintaining

urban aesthetics and therefore contributing to an improvement in the city’s sanitary

conditions.

10.2 Waste found in the street

Waste commonly found in the streets:

! material from road surface break-up;

! rubber from tyres and residues from brake pads and linings;

! sand and earth carried by vehicles or coming from wasteland and slopes;

! tree branches and leaves, weeds and other vegetation;

! paper, plastic, newspapers, packaging;

! domestic waste (in general in small amounts, principally on wasteland and areas

close to informal settlements);

! dog and other animal excrement (also in small amounts);

! particles from atmospheric contamination.

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Figure 45 - A street considered as“dirty”, with pieces of paper and plasticin the gutters

Figure 46 - A street considered as “clean”, with novisible refuse

The types of refuse that most offend citizens’ sense of hygiene and cleanliness are

papers, bits of plastic, packaging and the remains of food discarded in the street. A

gutter with some earth and material from road surface break-up is not perceived as

“dirty” by the general public while paper and plastic items are associated with “rubbish”

(i.e. types of waste that produce bad odours, have an ugly appearance and attract

undesirable animals).

More developed cities are giving increasing importance to a combination of cleaning

services and street conservation measures (maintaining street surfaces and pavements

in good condition, etc.) when defining quality standards for urban cleaning services

that are compatible with client-citizens’ ever more demanding criteria.

10.3 Street cleaning services

Street cleaning services in general include activities such as sweeping, weeding and

scraping; grass and vegetation cutting; drain cleaning; street market cleaning and waste

removal.

They can also cover other activities such as beach cleaning, the unblocking of drains,

pest control, disinfection, tree pruning, kerb painting and street washing.

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Figure 47 - Cross section of a street

10.3.1 Sweeping services

Characteristics of city streets

In surfaced streets most debris is found in the gutters (at the most 60 cm from the

kerb) due to the air displacement produced by passing vehicles that “pushes” dirt

towards the kerb.

In the streets themselves there is practically no dirt unless there is almost no traffic.

Rainwater also carries debris towards the kerb, in the direction of the drains, due to

the transverse curvature of the street. The gutters are in reality “channels” designed to

conduct rainwater.

In non-surfaced streets dirt and litter behave in a different way and it is necessary to

clean the entire width of the street.

It is essential to take these characteristics into account when determining street cleaning

methodology.

Restructuring manual sweeping routes

Review of the existing sweeping plan

The organization of existing sweeping routes should be examined. The review of the

plan should register the street sections that are swept on each route, the length of

each one (expressed in metres of pavement and gutter) and the teams assigned to it

(sweepers).

Service quality

As there is no process for determining precisely the degree, quality and standard of

cleanliness that each street requires, those responsible for urban cleaning have to use

their own criteria. They will determine the methodology and frequency of cleaning and

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131

will evaluate the approval or disapproval of the public according to the number and

content of complaints and suggestions received.

It is possible to gauge public opinion about cleaning services by carrying out opinion

surveys, investigating previous complaints and consulting press files.

Productivity tests

As each city has its own characteristics, habits and culture, it is advisable to evaluate

workers’ productivity in the field, that is, how many metres of gutter and pavement

can be swept per worker per shift.

This index is of fundamental importance for the restructuring of sweeping routes and

is usually measured in samples of typical residential, commercial and tourist streets,

and principal thoroughfares.

To carry out the tests, workers of medium performance are chosen and for a period

of approximately fifteen days the distance that each one sweeps in each type of

street is measured thus determining the average distance covered per shift.

Identification of sites that influence public opinion

Citizen participation is indispensable for public cleaning services to maintain an

appropriate level of cleanliness. Reference sites should therefore be established where

comparative studies can be made of resource mobilization and the quality of services

provide by the responsible body.

One of the first measures to take in order to improve services is the identification of

sites that influence public opinion, that is, certain streets that, if they are kept clean,

form and consolidate a favourable public opinion on the part of both residents and

tourists in regard to the cleanliness of the city, which then encourages the public to

cooperate in maintaining clean and hygienic conditions in the streets. These sites should

be photographed periodically to facilitate a comparative checking.

Tourist areas, principal streets and avenues, commercial centres and access roads to

the city are sites that influence public opinion.

Determination of sweeping frequency

The minimum sweeping frequency necessary to maintain the required level of cleanliness

in streets has to be determined.

This information is significant as, for example, if a street needs to be swept every day

double the number of workers will be needed than if it is swept every other day.

New sweeping plan layout

Once the existing plan has been examined and productivity indexes (metres of gutters

and pavements swept per worker per shift in each type of street), sites that influence

public opinion and minimum sweeping frequency for the different areas have been

determined, the new plan can be laid out on a map to a scale appropriate for the

relevant area.

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Figure 48 - Modern broom (1), sweeper broom (2), brush (3), small broom (4), key for drains (5),hoe for cleaning drains (6), shovel (7) and special waste collection pan (8)

Figure 49 - Manual sweeping

(1) (2) (3)

(4)

(5) (6)(7) (8)

Once the new plan is operational, the level of cleanliness achieved should be checked

through photos, and the reaction of the public should be evaluated through opinion

surveys and the registration of complaints, on the basis of which necessary adjustments

can be made.

Up to three workers can be assigned to each route but it is recommended that only one

is assigned to each route in order to clarify responsibilities and facilitate supervision.

Implements, tools and clothing

The principal tools and implements for manual sweeping are:

! sweeper broom (vegetable fibre or plastic);

! small broom and shovel, used to collect waste and finish sweeping;

! key for opening drains;

! hoe for cleaning drains and extracting waste from them.

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Clothing can be the same as for most urban cleaning service workers: trousers, t-shirt,

high closing shoes and cap.

For safety reasons the use of reflecting strips on the uniform is recommended,

particularly for nocturnal work.

Sweeper tasks

In general each sweeper should:

! collect domestic waste discarded in the street (not packaged for collection);

! sweep the pavement and gutter along the assigned route;

! empty rubbish bins;

! weed the gutters and areas around trees and posts (once every 15 days);

! clean rainwater drains on the route.

Types of sweeping

In spite of the cost, mechanical sweeping is recommended for some situations. A large

mechanical sweeper can sweep an average of 30 km of gutter per shift. As the average

productivity of the manual system is 2km of gutter per worker per shift, a mechanical

sweeper can replace 15 human sweepers.

However the monthly cost of renting a large mechanical sweeper in Latin American and

Caribbean countries can be equivalent to the wages of at least 18 sweepers and taking

into account the importance of job creation for citizens who have received little

education, manual sweeping is in general more appropriate.

Nevertheless there are exceptions, where roads with high volumes of fast moving

traffic, tunnels and bridges represent dangerous situations for manual sweeping. In

such cases it is advisable to consider the possibility of mechanical sweeping.

In tourist areas and city centres small mechanical sweepers can be used as they have a

positive impact on public opinion by demonstrating the efforts made and the resources

invested by the municipality in the urban cleaning sector.

The main mechanical sweepers used are mini-sweepers, mechanical sweepers with

vacuum system; mechanical sweepers without vacuum system; large mechanical

sweepers and mini-vacuums.

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Figure 50 - Mini-sweeper

Figure 51 - Mechanical sweeper without vacuum

MINI-SWEEPER

A self-propelled sweeper and vacuum machine with two front brushes and water

sprinkler nozzles to avoid raising dust.

These machines are used for the mechanical sweeping of pavements, squares,

pedestrian ways, etc. In general they provoke curiosity and create public awareness of

the municipality’s efforts to improve and modernize the urban cleaning system.

MECHANICAL SWEEPERWITHOUT VACUUM SYSTEM

A medium-sized self-propelled sweeper machine, without vacuum, with a 2.3m³

receptacle, two frontal brushes, one central brush and water sprinkler nozzles to avoid

raising dust.

These machines are used for the mechanical sweeping of roads with fast moving traffic

and represent a good option wherever human sweepers would be in danger of being

run over.

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Figure 52 - Large mechanical sweeper

MECHANICAL SWEEPERWITH VACUUM SYSTEM

A 14ton TGW sweeper machine with a capacity of 6m³ and a vacuum system driven by

an auxiliary engine. It has lateral and central brushes, both driven by hydraulic motors,

and water sprinkler nozzles to avoid raising dust.

LARGE MECHANICALSWEEPER

A self-propelled sweeper and vacuum machine with two lateral brushes, one central

brush and water sprinkler nozzles to avoid raising dust.

This machine is used for sweeping tunnels, bridges and large streets with high traffic

volumes. When its waste receptacle is full it can be emptied directly into a dump truck

that operates together with it, thus avoiding having to move the sweeper itself to

empty its load in a transfer station.

MINI-VACUUM

Small vacuum machine that sucks debris through a flexible tube manoeuvred by the

operator. This machine is used for cleaning cycle ways, pavements and parks.

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Figure 54 - Weeding

Figure 53 - Mini-vacuum

10.3.2 Weeding and scraping services

Where sweeping is not regularly undertaken or rain carries debris onto surfaced streets,

earth can accumulate in gutters and weeds begin to grow.

In such cases weeding and scraping services are necessary to remove earth from the

gutters and re-establish good drainage conditions and the appropriate appearance

of the street.

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Figure 55 - Hoe, pick and scraper

Figure 56 - Rake

In general these services are carried out using very sharp 3½ pound hoes and the

waste is collected using shovels or four pronged pitchforks. When the earth is very

compact hoes or picks are used to scrap it. A scraper is used to deal with mud.

Wheelbarrows, plastic bags, wheelie bins or stationary containers can be used for

waste collection operations.

Rakes can be used to complete weeding and brushes to finish the cleaning. It is

important that drains are cleaned at the same time as weeding and scraping operations

are undertaken, as they tend to become clogged when gutters are covered with

earth and weeds.

When there is a large amount of earth, usually after intense rain in streets close to

slopes, small or big mechanical loaders are used for scraping, depending on the amount

of material and on the type of access and space for manoeuvring.

Types of weeding

Weeding operations can be manual or chemical. The main advantages and disadvantages

of each method are listed below:

Manual

! uses unqualified labour;

! is a simple and well known method;

! involves fewer environmental risks, the main one being erosion processes due to

the inappropriate removal of vegetation;

! machines and tools are easy to obtain and operate;

! the operation uses more time;

! requires large numbers of workers.

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Figure 57 - Scythe, slicer and broad scythe

Chemical

! the operation uses less time and requires fewer workers;

! facilitates the removal of vegetation, which quickly dies;

! when done well, with appropriate techniques and products, it involves few

environmental risks;

! requires qualified labour;

! its use is restricted to specific situations and is always an auxiliary to manual weeding;

! represents a risk to the environment when used without fulfilling technical

requirements;

! the use of machines and tools involves diverse operating, cleaning and maintenance

techniques.

Planning of weeding operations

The first planning task is to determine the type of weeding: manual or chemical. This

decision depends on the characteristics of each particular area and the more common

method employed is manual weeding.

Chemical weeding uses herbicides and should always be undertaken in compliance

with the producer’s specifications and the relevant legal and environmental restrictions,

and exclusively under the guidance of a specialized professional.

It should only be used as an auxiliary and complementary method side by side with

manual weeding, and when it is adopted regulatory restrictions and requirements should

be rigorously observed as should the instructions on the product labels.

10.3.3 Cutting services

Cutting services are necessary when grass or vegetation is too long and can be carried

out manually or mechanically.

Manual cutting uses tools such as scythes and slicers that can also be used for cutting

tree branches. For the manual cutting of grass a broad scythe is used.

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Figure 58 - Manual cutting

Figure 59 - Portable cutter (backpack type)

Rakes can be used to complete the operation. The manual cutting of grass and other

vegetation with sickles or scythes does not produce good quality results or represent

good productivity (only 100m² per worker per day).

Mechanical cutting employs machines such as portable cutters, lateral cutters, tractor

cutters, tractor mounted side-arm cutters and cutters towed by an agricultural tractor.

Portable mechanical cutters that operators carry on their backs and cutters mounted

on small, medium and large tractors are currently available and produce a good quality

result with good productivity.

Portable cutters are suitable for rough land and places that are difficult for larger cutters

to access. One of these machines can cut approximately 800m² per day.

The cutters attached to tractors are appropriate for relatively flat land and can cut

between 2.000 and 3.000m² per day. For cutting operations on the borders of roads

cutters with articulated arms laterally mounted on agricultural tractors can be used.

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Figure 60 - Cutter attached to a tractor

Figure 61 - Long rake and four pronged pitchfork

Cut vegetation and the refuse that inevitably appears should ideally be gathered on

the day of the cutting operation using standard or long rakes. Waste can be put in

bags and cut vegetation organized into piles to await collection, which should not be

delayed for more than two days to avoid them catching fire or becoming scattered.

Four to ten pronged pitchforks and long rakes should be used for gathering and

removal operations.

Mechanical equipment for cutting vegetation

Commonly used mechanical equipment: portable cutter; chainsaw; tractor mounted

side-arm cutter; mini-tractor grass cutter; towed grass cutter and stationary or towed

branch-grinder.

Portable cutter

An approximately 11 kg cutting machine powered by a petrol engine with the rotation

transmitted to the cutting head through a flexible cable. The cutting can be done by a

blade, a disc or a nylon string depending on the type of vegetation. The nylon string is

appropriate for light vegetation and grass and where the machine is used as an edge

cutter, while the toothed disc and the blade are appropriate for thicker vegetation and

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Figure 62 - Backpack cutter Figure 63 - Chainsaw

Figure 64 - Tractor mounted side-arm cutter

bushes such as guinea grass (Panicum maximum). The machine’s useful life is short,

approximately 2,000 hours, after which maintenance costs are excessively high.

Precautions should be taken to isolate the area surrounding the work site because the

blades, which rotate at high speed, can throw out objects such as small stones from

under the vegetation with the risk of causing injury to people or animals.

Chainsaw

A tool powered by a two stroke petrol engine. It is used to prune and cut trees or large

branches, where for example they are likely to fall and cause accidents, principally

after storms and gales.

Tractor mounted side-arm cutter

A hydraulic arm with wheeled head that is mounted on the rear part of a medium-

sized agricultural tractor. At the extreme of the arm there is a hydraulically operated

rotating axis blade cutter. It is used to cut large lineal extensions such as roadside

strips and slopes.

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Figure 65 - Mini-tractor grass cutter

Figure 66 - Towed grass cutter

Mini-tractor grass cutter

A compact machine on wheels with a central blade. It is appropriate for cutting large

flat and even extensions of grass. This machine does not cut edges but has the

advantage of not throwing out stones or other objects while in use.

Towed grass cutter

An implement towed by an agricultural tractor. Its cutting width is up to 1.20m and is

appropriate for relatively flat land. As with the micro-tractor grass cutter, this implement

does not throw out stones or other objects while in use.

Stationary or towed branch grinder

This machine is powered by a diesel motor. Branches and foliage are fed into the

grinder and the ground material passes through a tube to be deposited in a dump truck

or container. It is used in areas with many trees and bushes where frequent pruning

takes place.

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Figure 67 - Branch grinder

An important rule for mechanical vegetation cutting:

Work should only be undertaken in a screened off area using protective netting to

stop the circulation of people near the area of operations in order to avoid people,

vehicles or objects being hit by stones thrown out by machines. Workers should use

all the recommended IPE (individual protection equipment).

10.3.4 Drain cleaning services

A well functioning street sweeping system significantly reduces the volume of waste

that falls into storm drain inlets or is carried there by rainwater. Consequently the

cleaning of drain inlet boxes is usually assigned to the body responsible for urban

cleaning. As some sweepers may otherwise sweep debris into the drain inlet boxes,

thus slowly clogging them, in general sweepers themselves are responsible for cleaning

them.

The first step of this operation is to remove the covering grill using a drain key. If the

grill is stuck it can be levered out. Where asphalt type material used for repairing the

road surface is partially covering the grill it can be removed with a hammer and chisel

taking care not to break the grill. The same procedures should be followed when

working with any type of rainwater drain.

Waste that has accumulated in drain inlet boxes can be removed using worn hoes,

which are narrower than new ones, grub hoes or special shell shaped tools.

Waste with a low specific weight (leaves and branches) can be put into bags and collected

together with sweeping waste. Earth extracted from drains should be collected by

dump trucks.

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Figure 68 - Clogged drain

Figure 70 - Pumping truck

(1)(2)

(3)

(4)

Figure 69 - Lever (1), hammer (2), chisel (3)and drain key (4)

Drain inlet boxes can also be cleaned using special machines with suction hoses (Vac-

All type) or sweepers with vacuum suction equipment.

The cleaning of the rainwater drainage network is done with special machines through

points of access to the drainage system.

A pumping truck is used in urban and industrial operations for cleaning drain boxes,

drain accesses, septic tanks, separated chambers and sewers. Waste is pumped through

a four inch diameter hose and the most commonly used models have a capacity of 6, 7

or 8m³ corresponding to a truck TGW of 12, 14 or 16 tons respectively.

Mechanical sweepers with suction systems usually have tubes appropriate for drain

cleaning.

The cleaning of drain inlet boxes in areas that are susceptible to flooding in the event

of heavy rain should be regarded as a priority.

10. Street cleaning

145

Figure 71 - Containers located close to a market

10.3.5 Market cleaning services

In most Latin American and Caribbean countries there are informal public street markets

set up particularly for the sale of vegetables, fruit, fish and other types of food. Many

people go to them and generate large amounts of waste.

It is therefore necessary to plan appropriate cleaning services in order to keep the

markets clean from the moment they begin functioning until the stalls are dismantled.

Market cleaning is done manually and the size of teams should correspond to the size

of the market, i.e. the number of stalls and the number of people visiting it.

Independently of the market cleaning services that it provides, the Municipality should

take firm measures to ensure that stall operators themselves avoid waste being

discarded in the street and install receptacles to store waste by their own stalls.

While large markets are functioning workers can be collecting waste produced by stall

owners and their customers by circulating with manual collection carts lined with large

plastic bags. When full these bags can be kept at a storage point adjacent to the

market in a location chosen to incur the minimum possible nuisance to the public and

facilitate collection by the collection vehicle.

Where possible 240 litre plastic containers with lid and wheels should be used to store

waste produced while the market is operating. Special attention should be given to

stalls selling fish, chicken and pork products.

When the market is dismantled a larger team of between four and eight workers

sweeps and cleans the area. For this task sweeper brooms are used together with

shovels and brushes for collecting the waste. In some cities large wooden squeegees

are used as an auxiliary tool. Waste is collected by a compactor truck or a dumpster

carrier truck.

146

Once it has been swept the street should be washed by a street washing truck with

a pressure water jet, paying particular attention to areas around fish stalls sites,

which, along with the drains, should be washed with disinfectant and deodorant

products.

Figure 72 - Sweeper broom (1), brush (2), wooden squeegee (3)and shovel (4) used in market cleaning

(2)

(3) (4)

(1)

10.3.6 Manual and mechanical waste removal services

In many cities with large wasteland areas refuse is often irregularly discarded there.

Open wastelands and uncared for public areas, in combination with inadequate urban

cleaning systems, generate what are called “waste accumulation sites”.

The accumulation often begins with construction rubble being dumped and, as “rubbish

attracts rubbish”, this is followed by the addition of pruned vegetation, old tyres, the

remains of packaging, and organic waste. Later weeds start to grow and the entire

scenario results in blocked drains and serious sanitary and environmental consequences.

To deal with this type of problem cleaning services should establish a specific

operational methodology as these situations involve not only clearing activities (weeding

and vegetation cutting) but also the removal of all types of waste that have accumulated

on such sites. This work requires machines and tools appropriate for each type of

waste, not only for clearing tasks but also for collection and transport to the final

destination, all of which places an additional burden on the system through higher

operational costs due to the extra personnel and machines required in these cases.

This type of activity is commonly called waste removal and can be manual or

mechanical.

The removal of unpackaged refuse such as common waste, soil and rubble can be

done manually with shovels, lifting it directly into the box of a dump truck or into

metal containers that will later be removed by appropriate trucks with cranes. To

remove cut vegetation a four pronged fork is used. A three or four pronged pitchfork

10. Street cleaning

147

Figure 73 - Mechanical loader at work

Figure 74 - Three pronged pitchfork

is used to separate the pile of accumulated waste in order to facilitate its handling

and transport.

In cases where there is a large amount of waste and especially where a lot of soil or

rubble has to be removed the use of a wheeled front loader (mechanical loader) is

recommended.

10.3.7 Beach cleaning services

Sandy beaches have to be kept clean by the application of various complementary

measures.

The first and most important of these is to reduce the amount of waste that gets onto

the beach by installing rubbish bins both on the beach itself and on pavements that

border it so that people can deposit waste in them. Each summer, awareness raising

campaigns should be initiated to promote the use of rubbish bins for waste generated

on the beach. Where it is not possible to install purpose made rubbish bins, alternative

structures for depositing waste can be used such as setting vertical concrete pipe

sections on the beach lined with plastic bags.

Once these basic measures have been adopted, the planning of services should involve

the following principal elements:

! the frequency of beach cleaning operations should be organized with a view to the

beach always being as clean as possible and in good condition for use by citizens;

! the timing of operations should be compatible with beach activities so as not to

inconvenience users;

! labour requirements are calculated according to the surface area to be maintained,

the required frequency of operations and productivity rates determined by field

measurements;

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Figure 76 - Waste containers

Figure 77 - Manual removal of beach waste

Figure 75 - Wire rake (1), plastic net sieve (2), ten pronged pitchfork (3), concrete pipe sectionwith plastic bag (4) and container (5)

! service organization can be based on defined sectors or on the entire extension of

the relevant beach.

Beach cleaning services can involve both manual and mechanical operations.

The manual cleaning of the beach surface should ideally be done at the end of every

sunny day using wire rakes (usually having 20 to 25 prongs with a 1cm gap between

them), ten pronged pitchforks and plastic net sieves, as well as plastic bags and

containers for carrying the waste to the compaction vehicle or dump truck that

accompanies the team as it progresses.

The labour productivity rate varies depending on diverse factors such as user behaviour

and the availability of rubbish bins. An average of 1.000m² per hour per worker can be

taken as an initial base value.

(2)

(3)(4)

(1)

(5)

10. Street cleaning

149

Figure 78 - Transfer of beach waste from atractor drawn trailer to a truck

Figure 79 - Manual beach cleaning

Figure 80 - Mechanical beach cleaning

Mechanical cleaning is appropriate for beaches with large amounts of waste and big

extensions of sand. In these cases purpose built machines towed by agricultural tractors

are used and have a productivity of approximately 10,000m² per hour. This type of

cleaning collects large and medium-sized waste but leaves ice cream sticks, straws,

cigarette ends and food remains.

On very wide beaches (where there is more than 30 metres of sand between the

water and the land), four wheel drive agricultural tractors with trailers can be used to

accompany the cleaning team as they progress along the beach and transport waste to

a truck similarly progressing along the street bordering the beach.

In out of season periods beaches should be cleaned with machines that stir the sand,

pass it through a vibratory sieve in order to catch smaller objects and produce a

bactericidal effect by exposing lower layers of sand to sunlight. Beach cleaning machines

towed by four wheel drive mini-tractors with a maximum potency of 60hp are used.

The operation of this machine is entirely mechanical. Sand is taken from a maximum

depth of 20cm, sieved, aired and returned to the beach. The type of net used in the

sieve varies according to the characteristics of the beach.

150

Figure 81 - Smooth pavements and guttersfacilitate cleaning

Figure 82 - Uneven gutters make cleaningdifficult

Figure 83 - Rubbish bins

An option that may be considered for very crowded beaches is to replace sand above

the tide line with sand from below it that has been washed by the sea and is therefore

cleaner. Such an operation should be carried out using tractor-bulldozers and mechanical

loaders after an environmental study has been undertaken by specialists.

10.4 How to reduce street waste

The amount of solid waste in streets can be reduced through:

! smooth surfaces and appropriate inclination for streets, gutters and pavements;

! appropriate dimensions and maintenance for rainwater drainage systems;

! planting tree species in combinations that do not result in abundant leaf fallings

several times a year;

! instalment of rubbish bins in streets with high pedestrian concentrations, on corners,

at bus stops and in front of bars, cafes and supermarkets;

10. Street cleaning

151

Figure 84 - A dirty square

Figure 85 - Waste being swept into the street

! regular sweeping and waste removal from waste accumulation sites (“rubbish attracts

rubbish” while “cleanliness promotes cleanliness”);

! public awareness raising campaigns related to the maintenance of cleanliness;

! establishment of legal devices that sanction citizens who disobey urban cleaning

regulations.

As can be seen, urban cleaning issues are related to various aspects of public urban

works and should be taken into account by the respective municipal bodies when

urban improvement projects are being planned.

The dirty and uncared for appearance of the square is added to by so-called “white

waste”, made up of papers, plastic and packaging.

In general it can be observed that in well cared for and well maintained streets passers-

by are more conscious of cleanliness and discard less rubbish on the ground.

Commercial establishments should not be allowed to sweep their waste onto the

street. Those who persist in doing so should be fined and for this the municipality

needs to have a good supervision system.

(Figure 85)

Figure 85 –

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Figure 86 - “Molok” type container in use

10.5 Street cleaning in tourist cities

As is the case with domestic waste collection, an influx of tourists to a city causes

considerable problems for the street cleaning service, principally in regard to sweeping

and, in the case of coastal cities, beach cleaning.

An underlying cause of these problems is the temporary population increase and the

resultant increase in demand for public services. A good example is the increase in

the number of people circulating through the streets and the consequent generation

of waste in different quantities and at different times than those in the normal routine

of the city.

Another aspect that creates difficulties for cleaning services is that in general tourists

are not acquainted with the operational routine of cleaning in the city and many times

they do not do what they should as users to cooperate with the body providing the

service.

There are also cultural and behavioural questions with some tourists who take the

view that as it is not their city they are not interested in keeping it clean. They discard

rubbish indiscriminately and fail to comply with behavioural norms and regulations. These

however are the same tourists who will not return to the city if they consider it dirty or

not well cared for.

In regard to sweeping, the measures that have to be implemented to maintain required

levels of street cleanliness are:

! increase the hours of work shifts (overtime) on some sweeping routes in order to

respond to the greater seasonal demand for services, taking into account the limits

imposed by employment legislation;

! restructure existing routes increasing the number of sweeping shifts and contracting

extra workers on a temporary basis.

10. Street cleaning

153

It is also important to increase the numbers and maintenance of containers and rubbish

bins strategically positioned in streets, squares and other public spaces to facilitate

appropriate waste disposal. The aesthetics of these units and their integration with

the landscape should be taken into account.

In the case of coastal tourist cities the problems are more difficult to solve as, with

few exceptions, they do not maintain teams exclusively for beach cleaning services,

which are complex, difficult to mechanize and relatively labour intensive. For an effective

provision of this service during the tourist season the most appropriate course of

action may be to contract a separate team to undertake the cleaning of the beach and

its bordering seafront, and equip it with all the tools necessary to carry out this service.

Extending work shifts and giving seasonal tasks to workers who normally perform

other activities is in general neither feasible nor sufficient to solve the problem

completely.

One general administrative measure that a municipality can take to reduce problems

faced by the urban cleaning sector during the high tourist season is to schedule

employees’ holidays for the months of the low season so that during periods when

demand for services is at its greatest the entire staff is available.

An ongoing awareness raising campaign can be run throughout the high tourist season

with the participation of companies that benefit from tourism, such as hotels, restaurants

and entertainment establishments. The campaign should encourage people to take

better care of the city and guide visitors to cooperate in maintaining hygienic conditions

and cleanliness in the streets. Such a campaign can and should be directed to the

entire city but may concentrate more on neighbourhoods associated with tourism and

along the seashore where applicable.

154

Recovery of recyclable materials11

11. Recovery of recyclable materials

155

Reduce, the less waste the better;

Reuse, maximize or diversify the use of a given consumer product;

Recycle, a positive contribution where reduce and reuse are not applicable;

Recover, mostly associated with energy generation.

11.1 Concept

With the growing prominence of environmental conservation policies citizens are

becoming increasingly concerned about solid waste issues. The increased per capita

waste generation, fruit of capitalist society’s high consumption model, not only

concerns environmentalists but also governments and the general public. This concern

with waste issues is due both to the potential for contamination and the continuous

need to find new final disposal sites, not to mention the negative impacts caused by

an irrational consumption of non-renewable natural resources.

On an international level these issues have prompted a debate about the consumption

habits of societies and the responsibility of companies, resulting in what is known as

4Rs practice (Reduce, Reuse, Recycle and Recover). This concept establishes the

principle of waste generation prevention, taking as its departure point reduction.

That is, a reorientation of consumers’ needs and purchasing preferences, and

therefore of companies’ production, favouring products that are less damaging to

the environment and avoid wastage. In spite of the integral nature and order of the

4Rs, recycling is the one that provokes most public interest principally due to its

clear claims to environmental benefits.

4 Rs practice:

reduce – aimed at diminishing the amount of disposable packaging and containers,

through a change in consumption habits. The reorientation of consumers’ preferences,

favouring products with more durability and less packaging, putting pressure on producing

companies to use the least amount of packaging possible.

reuse – the reuse of a material or product without changing its shape or original nature.

Different types of waste can be reused such as bottles, newspapers, magazines, books

and other products.

recycle – the transformation of materials into raw material for production processes.

This process requires the segregation of waste at source, in transfer stations or at

final disposal sites. One of the most important incentives for recycling is the saving of

energy and natural resources.

recover – principally related to appropriate waste incineration processes that produce

energy and consequently conserve fossil fuels.

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11.2 Selective collection programs

A significant role can be played by educational programs that promote 4Rs practice

and foster the development of environmental awareness amongst citizens. These

programs, for the most part related to pre-recycling waste segregation, can become

instruments for income and employment generation, particularly in less developed

countries.

This aspect has a significant relevance to many Latin American and Caribbean cities

where social crises have resulted in large numbers of people turning to refuse

segregation as a means of survival through the commercialization of recyclable materials,

almost always in extremely precarious conditions.

The principal benefits of recycling discarded materials (plastic, paper, metal and glass)

are:

! the saving of non-renewable raw materials;

! the saving of energy in production processes;

! the prolongation of sanitary landfills’ useful life;

! the generation of income and employment.

The great challenge in implementing selective collection programs is to find a model

that is in itself economically sustainable. Traditional models applied in developed

countries almost always involve public subsidies and are difficult to apply in developing

countries. However the social and environmental benefits of these programs also have

to be considered.

In practice, a model involving the selective collection of materials at the source of

generation (houses, offices, shops and factories) and associated with a program of

income and employment generation, is the one most applied in Latin American and

Caribbean cities.

A scarcity of resources often hinders the implementation of such programs but some

municipalities are endeavouring to promote alternative models adapted to fit their

particular economic circumstances.

For example, where large parts of the population live in poor socioeconomic conditions

projects can be established that involve the “bartering” of recyclable materials for

food and an increased level of community participation.

Another example is the establishment of partnerships between public authorities and

civil organizations, such as segregator cooperatives, in which the latter undertake the

collection of materials.


157

Figure 87 – Selective collection by compactor truck

Figure 88 – Selective collection by truck without compaction

Amongst the options available for the segregation of recyclable materials at the source

of generation are:

! selective door to door collection;

! voluntary drop-off centres;

! segregator organizations.

11.2.1 Selective door to door collection

The most commonly used model for selective collection programs is the segregation by

residents of discarded recyclable materials, which are then collected by specialized vehicles

from each housing unit, in a similar way to conventional domestic waste collection.

The separation of recyclable materials in households can be done in two ways:

identifying and separating different types of recyclable material and storing them in

separate containers, or putting all recyclable materials in one container.

158

Figure 89 – Recyclables segregation plant

The system in which different types of recyclable materials are separated requires

more space for keeping the containers, one for each type of recyclable material, which

makes it more difficult in apartments or small houses. This model also requires a

collection truck with a box divided into compartments to transport materials separately.

With the other more commonly used model residents separate domestic waste into

two categories:

! organic material (damp) – including the remains of food and non-recyclable materials

that are stored in a container for this category and are collected by the normal

domestic waste collection service;

! recyclable materials (dry) – paper, metal, glass and plastic, which are stored in a

container for this category and are collected by the selective collection service.

In most cities where the system is operated, door to door selective collection can be

made once a week using open box trucks. The relatively long interval between selective

collections is possible because of the inert nature of recyclable materials.

Once collected, recyclable materials should be transported to a segregation plant,

generally equipped with tables, where materials are separated by type in preparation

for their commercialization.

Segregation plants should also have presses so that materials with a lower specific

weight (paper and plastic) can be baled to facilitate storage and transport.

It is important that the public is clearly informed of the correct criteria for the separation

of materials for commercialization in order to avoid the expense incurred with

transporting and handling non-recyclable waste at the segregation plant.

The principal disadvantages of door to door selective collection are the increased

transport costs involved in the need for extra collection trucks and the high unitary

cost of collection compared with conventional collection.


159

Source: CONAMA resolution Nº 275 of 25/4/2001 (Brazil)

Both before and after the initiation of selective collection services the public authority

should continuously encourage citizen participation through promotional campaigns

and environmental education. Consequently planning for a project has to allow for

the necessary resources to run such campaigns, which are fundamental to maintaining

citizen participation levels.

Selective collection is not profitable when the municipality uses its own vehicles,

labour and structure. Ideally it should standardize, regulate and foster the process

without participating directly in its operation. As an incentive it could invest in

warehouses and equipment such as bale-presses, grinders, washers, etc. to add value

to the recyclable material.

A selective collection system in which a municipality does not directly participate but

establishes alliances with the community for operating it, results in significant economic

benefits for the urban cleaning system as previously segregated recyclable materials

will not need to be collected, transported and disposed of in a landfill, all of which

reduces the costs and work of the municipality.

11.2.2 Voluntary Drop-off Centres (VDC)

Containers sited in public places for the public to voluntarily deposit pre-segregated

recyclable waste.

The responsible public body usually standardizes the program to facilitate organization

and community participation. It can for example define a colour code for the different

types of waste, which will then be used for identifying containers and collection

trucks, as well as in waste segregation educational campaigns. See the suggestions in

table 15.

Table 15

Container colour

Colour code for recyclable solid waste

Paper and Cardboard

Plastic

Glass

Metal

Organic waste

Blue

Red

Green

Yellow

Brown

Recyclable material

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Figure 90 - Special containers for a VDC

Figure 91 - Examples of VDCs

VDCs can be set up in partnership with private companies that can for example finance

their installation in return for the use of the site for advertisements.

Some municipalities are establishing partnerships with recycling companies that finance

both the installation of containers and the collection of materials deposited in them.

The establishment of VDCs in tourist areas should take into account potential

communication problems with the labelling of containers. To overcome the language

problem it is recommended that images are used to indicate the correct storage

container for each type of recyclable material.

Here too it is important to regularly empty VDC containers in order to avoid irregular

waste accumulation on the site.


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4 . Segregators from several Latin American countries met to define common strategies at the first and second LatinAmerican Congress of Recyclable Material Segregators, held in Brazil in 2003 and 2005.

11.2.3 Segregator organizations

The appearance of numerous segregator organizations in Latin America and the

Caribbean during recent decades reflects not only the socioeconomic crises that many

of these countries have experienced but also segregators’ capacity for articulation

and organization, which though still incipient has nevertheless grown significantly 4.

In spite of advances, working conditions for most segregators are still very precarious

and many of them continue to work without any support or acknowledgement.

Improvements in this sector’s working conditions depend to a large degree on several

institutions having an articulated vision and commitment that leads to the formulation

and implementation of effective public policies.

Many municipalities, in an effort to include a social dimension in their selective collection

programs or pressed by groups of segregators themselves, establish some type of

agreement or partnership with segregator cooperatives that then undertake the

collection and separation of discarded recyclable materials.

The principal advantages of working with segregator organizations are:

! the generation of income and employment;

! the social inclusion of segregators (who mostly live in the streets) as citizens;

! a reduction in the costs of selective collection programs;

! the organization of segregators’ work to avoid untidiness in waste collection and

the storage of materials in the streets;

! a reduction in the costs of the city’s urban cleaning system due to the collection of

part of the waste by segregators leaving less waste for collection, transportation

and final disposal.

Such savings on costs should benefit segregator organizations in the form of investment

in uniforms and infrastructure (warehouses for segregation and storage, standardized

carts, presses, bale lifters) so that the segregated materials increase in value in the

recyclables market.

It is important that municipalities adopting this model offer institutional support to

segregator organizations, principally in regard to granting the use of physical space,

providing juridical and administrative assistance for legalization processes and, as has

already been mentioned, providing basic equipment such as bale-presses, carts, etc.

Assistance should also be provided for the training of organization members to promote

greater autonomy.

One of the main factors that fosters the strengthening and success of segregator

organizations is the profitable commercialization of recyclable materials. The less

162

Figure 92 – Segregators from a cooperative working in the street

intermediaries that are involved in the process between the segregator organizations

and the final consumer (the recycling industry) the higher the sale price will be. The

following basic conditions should be met:

! good quality material (sorted by type of material, with a low impurity content and

appropriate packaging or baling);

! ample scale of production and storage: the larger the production and the quantity

available to the buyer, the better the selling conditions;

! regular production and delivery to the final consumer.

These conditions are rarely achieved by small groups but the organization of joint

commercialization centres is an option that creates better conditions for direct

negotiations with recycling companies.

When a public authority enters into partnership with a segregator organization it is

important that it continues to offer institutional support for the provision of basic

needs, the lack of which would hinder efficient performance, especially when

operations are beginning to be established.

Amongst the measures that should be taken in support of segregator organizations are:

! administrative and accounting support, the contracting of a professional specialized

in management to train the group;

! implementation of a social assistance program for segregators and their children;

! provision of uniforms and individual protection equipment;

! implementation of literacy courses and training for segregators;

! implementation of rehabilitation programs for those with a dependency on chemical

substances;

! implementation of environmental education programs for segregators.


163

Taking into account the lack of experience of those running the organizations, the

public authority can, during the initial phase, also help with the commercialization of

recyclable materials. For the eventuality of difficulties related to fluctuations in the

buying market, it is recommended that the group has a small liquid capital so that

segregators’ minimum incomes are guaranteed until better commercialization conditions

are re-established.

All these initiatives and types of support should be applied with a view to eventual

sustainability, that is, it is important that the strengthening of the segregator groups

leads in the long term to them gaining more autonomy and independence in their

activities.

164

Solid waste treatment12

12. Solid waste treatment

165

The most effective treatment is applied by the general public whenthey take action to reduce the amount of solid waste by avoiding

wastage, reusing materials, separating recyclable material at sourceand appropriately disposing of waste.

12.1 Concept

Between collection and final disposal municipal solid waste can be subject to

processes that produce technical-operational, economic and sanitary benefits. These

processes, known as waste treatment, contribute to human and environmental

protection.

The objectives of solid waste treatment are to reduce its volume and to lower its

contaminating potential by transforming it into inert or biologically stable material.

Processes applied to solid waste can be mechanical, thermal or biological.

Mechanical

! classification – sorting by economic criteria or as a preparatory step for subsequent

processing;

! grinding – reduces the granulometry and volume of waste as well as mixing and

homogenizing it;

! compaction – reduces empty spaces (increases waste density).

Thermal

! incineration – controlled burning at high temperature in purpose built equipment

with environmental control devices;

! pyrolysis – thermally induced waste degradation in the absence, or limited presence,

of oxygen at a lower temperature than that involved in incineration, producing high

energy liquids and gases and less atmospheric contamination.

Biological

! aerobic – stabilization and composting processes that principally generate water,

carbon dioxide and heat;

! anaerobic – important for the production of methane. Waste degradation is slower

and generates fatty acids, acetic acid, other acids of low molecular weight and some

unpleasantly smelling toxic gases such as sulfhidric acid (H2S).

166

The recycling process comprises: the segregation of materialssuch as paper, plastic, glass and metal from domestic solid waste,their sale to specialized companies and their transformation into

material for producing goods that can be sold in the consumermarket.

12.2 Domestic solid waste treatment

12.2.1 Recycling

Recycling offers the following advantages:

! conservation of natural resources;

! energy saving;

! economies in solid waste transport costs and in the occupation of landfills (as the

amount of waste to be transported to the landfill is reduced);

! generation of income and employment;

! greater public awareness of social and environmental problems.

The ideal recycling system begins with the separation of solid waste in homes so that

only potentially recyclable materials are sent to segregation plants. Such prior separation

reduces the amount of contamination affecting materials and in consequence increases

the productivity of segregation plants.

Recyclable material segregated from mixed solid waste is dirty and contaminated, so its

processing is more complicated and expensive.

Recyclable material contained in general domestic solid waste can be separated in the

segregation plant through manual or electromechanical processes that in terms of weight

usually yield only 3% to 6%, depending on the plant’s size and degree of sophistication.

The high cost of recyclable material transformation processes has resulted in many

recycling companies not following environmental guidelines stipulating the use of clean

(but expensive) technologies. If the necessary precautions are not taken recyclable

material transformation processes can be extremely harmful to the environment. In

such a case, the outcome is much worse than if the waste had been disposed of in a

sanitary landfill, together with the rest of the domestic waste, where it would be subject

to more rigorous environmental controls.


167

Figure 93 - Flow chart of the process and mass fraction proportions

Landfill RefuseRefuse

Grinding of the predominantly organic fraction

Grinding of the predominantly organic fraction

Selection table

Pre-selection of bulky objectsPre-selection

of bulky objects ReceptionReception

Storage of compostedground material

Storage of compostedground material

Compostcuring pilesCompost

curing piles

Recyclablematerials

Recyclablematerials

Organicpreparation (compost)

RefuseRefuse SievingSieving

Recoverablematerials

Recoverablematerials

Loss of matterheat+CO +water

189kg/day (12.6%)

225kg/day (15%)60kg/day(humidityloss 4%)

456kg/day (30.4%)

Domesticwaste collection

After the segregation of recyclable material that can be used for production, the rest

of the domestic waste, which is fundamentally organic, can be processed to obtain

compost for agricultural use. This subject is dealt with in the next section.

The gravimetric values (in weight) of the different types of solid waste after processing

in a segregation plant with a composting unit, and their uses, are in general as expressed

in the following flow chart of a hypothetical plant with an intake capacity of 1,500kg/

day (see figure 93). It can be seen that, provided there is compost production, from

the total amount of waste that arrives for processing only 12.6% needs to be transported

to the final disposal site. This material is inert and therefore not contaminating because

the residual organic content has been stabilized with most of the organic matter being

transformed into compost.

These percentages however are based on the optimum operational performance

conditions for a segregation and composting plant, which are:

! small-sized unit (low quantity of waste to be processed) which facilitates maximum

efficiency of manual segregation;

! reception of domestic waste from differentiated collections, thus avoiding a mixture

of recyclable and non-recyclable waste and reducing the percentage of non-

recoverable waste;

! existence of a strong and diversified market for recyclable materials so that the

commercialization of a wide range of materials is possible, thus reducing the amount

of non-recoverable waste.

168

In the case of bigger recycling and composting units (in large cities) the level of recyclable

material recovery tends to be less and the amount of disposable material for treatment

greater, which results in a larger percentage of non recyclable waste at the end of the

process.

As in practice optimum conditions rarely exist, the average production of non-

recoverable waste in recycling and composting plants can be estimated as 25% of the

total weight of refuse processed there.

Clearly this proportion depends on the composition of the domestic solid waste

generated in each city, which can be affected by local particularities, as mentioned in

chapter 5.

The operation of a segregation and composting plant is divided into three stages: re-

ception, feeding and selection.

Reception

Here collection trucks unload domestic solid waste and the following processes are

applied in sequence:

! determination of the volume or of the weight using a weighbridge, or in smaller

establishments by means of estimative calculations;

! storage of unloaded waste in silos or warehouses of a size compatible with the

daily processing capacity.

Feeding

The loading of waste onto the processing line by means of machines such as loaders,

overhead cranes, or hydraulic arm grabs. In smaller plants feeding can be manual.

In bigger establishments devices can be used to enable trucks to unload solid waste

directly onto the processing lines, thus freeing the operation of the processing lines

from dependence on the functioning of feeding equipment.

Selection

In this sector the flow of waste on the selection lines is regulated and segregation by

type of recyclable material is carried out.


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Figure 94 - Manual selection in a small capacity recycling plant

Equipment used for flow regulation comprises metal conveyor belts and mixer drums.

The latter are appropriate for plants with a maximum capacity of 10tons per hour

per line.

The selection conveyor belt speed should be 10 to 12m/min, to allow sufficient time

for the manual separation of materials by the segregators.

Segregators are stationed along the selection belt next to channels or containers. The

ones near the beginning of the conveyor belt separate larger objects (paper, cardboard

and sheet plastic) so that smaller objects (aluminium cans, glass containers, etc.) can

be seen and separated by segregators nearer to the end of the line. In general, the

first position on the selection line is occupied by a worker who breaks open bags and

scatters their contents across the width of the belt in order to facilitate the work of

the other segregators.

In establishments that have several parallel selection belts they should be installed on

a level that is high enough to allow for a level below them where baling presses can

operate and there should be enough space available for moving segregated materials.

The distinct selection processes can be set up independently of each other or be

interconnected. In general simple plants only have selection conveyor belts, while more

complete ones use other equipment that itself removes recyclable materials or assists

manual segregation. Examples of auxiliary equipment are: sieves, ballistic separators,

magnetic separators and pneumatic separators.

In plants that process up to 10tons/day, instead of a selection belt, a concrete table

can be used that should be slightly inclined and have raised lateral borders to avoid the

fall of waste. Waste is manually pushed along the table by segregators using small

planks as recyclable materials are withdrawn. In this type of plant the waste that arrives

from collection is unloaded close to the end of the selection table and is transferred

to the table by a worker with a pitchfork or another appropriate tool.

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Figure 95 - Manual selection in a large capacity recycling plant

Large capacity recycling plants need to use a high level of mechanization for feeding

and the movement of the large volumes of waste along the operational lines.

The type of recyclable material that will be separated in a segregation plant depends

above all on demand from the industry. However in most plants the following materials

are segregated:

! paper and cardboard;

! hard plastic (PVC, HDPE, PET);

! sheet plastic (low density polyethylene);

! entire bottles;

! transparent glass, coloured glass, mixed glass;

! ferrous metal (cans, sheet metal, etc.);

! non-ferrous metal (aluminium cans, lead, antimony, etc.).

It is important to note that a segregation plant can only operate if the urban cleaning

system of the city includes the selective collection of hazardous waste, such as medical

waste. It is essential that this type of material does not arrive at the segregation plant

in order to avoid endangering workers who handle the waste. Street sweeping waste

and construction rubble should also not be brought to the segregation plant as they

contain materials that can damage the machines.

12.2.2 Composting

Composting is the natural biological degradation of organic materials (with carbon in

their structure) of animal or vegetable origin through the action of micro organisms. It


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Hummus is a completely bio-stabilized homogeneous organic substance,dark in colour and high in colloidal particle content that when applied to

soil improves its physical characteristics for agriculture.

is not necessary to add any type of substance, including chemical substance, to the

mass of organic domestic waste for composting to take place.

Composting can be aerobic or anaerobic, depending on the presence or absence of

oxygen in the process.

In anaerobic composting, degradation is caused by micro organisms that live in

environments without oxygen; it takes place at relatively low temperatures, emits a

strong unpleasant odour and requires more time for the organic matter to stabilize.

In aerobic composting, the more appropriate treatment for domestic waste,

degradation is caused by micro organisms that only live in environments containing

oxygen. Temperatures can reach 70ºC, odours are not unpleasant and degradation is

quicker.

The final product of an organic waste aerobic composting process is compost, a material

rich in hummus and mineral nutrients that can be used in agriculture to improve soil

quality and as a fertilizer.

Stages of composting

The aerobic composting process can be divided into two stages.

The first stage, bio-stabilization, involves a significant increase in the temperature

of the organic mass, reaching 65ºC and later stabilizing at the ambient temperature

towards the end of the cycle, which in natural composting systems takes

approximately 60 days.

The second stage, maturing, takes another 30 days. In this stage the humidification and

mineralization of the organic matter takes place.

Factors that influence composting

A sufficient quantity of the micro organisms necessary for degrading organic matter

is inherently present in domestic waste. If humidity and airing are appropriately

controlled these micro-organisms proliferate quickly and homogeneously throughout

the mass of waste.

The waste also contains pathogenic micro organisms such as salmonella and streptococcus.

These pathogenic agents are eliminated by the heat generated in the biological process

as they do not survive temperatures in excess of 55ºC for more than 24 hours.

Structurally the micro organisms that degrade the organic matter are approximately

90% water, therefore the water content has to be controlled during the process.

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Figure 96 - Aerobic composting in a small capacity plant

In aerobic composting the metabolism of the micro organisms needs oxygen. Factors

such as humidity, temperature and granulometry influence the availability of oxygen. A

lack of oxygen produces unpleasant odours.

Compost is aired by stirring the material with mechanical loaders or special machines.

In small units it can be stirred manually with pitchforks or other tools.

During the aerobic stage the more the matter is exposed to oxygen, the quicker the

degradation. In addition, the smaller the particles, the greater the surface area that is

exposed to oxygen and therefore the shorter the composting process. However, if

particles are too small an excessively compacted mass can result, which makes the

airing process more difficult.

Simple composting plants

Simple plants make compost naturally in the open air. In such plants the waste is

fragmented in a hammer-mill and then “piles” are set. The organic matter remains there

until its bio-stabilization and is stirred with a predetermined frequency (for example,

on the third day after the formation of the pile, and from then on, every 10 days until

completing 60 days). Once it is biologically stable the material is refined in a sieve and

is ready to be used in the preparation of agricultural soils.

The surface of the area where piles are set in a composting plant should be smooth,

well compacted and if possible surfaced, with enough of a slope (2%) for rainwater

and leachates produced in the composting process to run off. These effluents, which

in well managed piles are produced in very small quantities, should be sanitarily treated

in stabilization ponds.

When designing the composting area sufficient space has to be planned for between

the piles so that trucks, mechanical loaders and special machines for stirring the piles

can circulate. Sufficient space for the storage of compost that is ready for use should

also be made available.

Composting piles should have a pyramidal or conical shape, with bases of up to 3m per

side or 2m diameter and be no more than 1.50m to 2m in height.


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Figure 97 - Aerobic composting in a large capacity plant

Organic matter

Total Nitrogen

Humidity

C/N relation

PH

> 40%

> 1.0%

< 40%

< 18/1

> 6.0

- 10%

- 10%

+ 10%

21/1

- 10%

Table 16

Values established in Brazil for commercialized compost

Parameter Value Margin

If the height of the piles is more than 2m it is difficult to stir and air the organic mass.

A conical form facilitates the running off of rainwater and avoids the pile becoming

saturated.

Characteristics of compost

The principal characteristic of compost produced by domestic waste composting is

the presence of hummus and mineral nutrients, the amounts of which determine the

quality of the compost.

Hummus makes soil more porous thus facilitating the airing of roots and the retention

of water and nutrients. Mineral nutrients can comprise up to 6% of the weight of the

compost and include nitrogen, phosphorus, potassium, calcium, magnesium and iron,

which are absorbed by plant roots.

Compost can be used for any type of cultivation, whether or not chemical fertilizers

are being used. It can be used to correct soil acidity and rehabilitate eroded areas.

Compost quality

In general compost quality is standardized on the basis of parameters established by public

institutions in each country with a view to ensuring its effective application in agriculture.

In Brazil, for example, commercialized compost produced by domestic waste composting

plants must comply with minimum values established by the Ministry of Agriculture.

These values are presented in table 16 as a reference.

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Compost must be periodically subject to physical and chemical analysis in order to

verify its compliance with the minimum quality standards established by the relevant

governmental body.

One of the main concerns of compost users is the presence of heavy metals in sufficient

concentrations to be prejudicial for cultivation and/or produce consumers. Some

components of domestic waste such as coloured paper, textiles, rubber, ceramics and

batteries contain heavy metals. Composting plants’ segregation operations must remove

these materials as much as is possible from the waste that is received.

In most Latin American and Caribbean cities, especially in small and medium-sized ones,

it is unlikely that compost produced from domestic waste will contain a concerning

level of heavy metals because of the socioeconomic characteristics of most of the

population and therefore the type of waste generated.

12.2.3 Choosing a treatment option

Segregation and/or composting plants are alternatives that municipalities should consider

when planning the treatment of domestic solid waste that they collect.

However, before proceeding they should examine the practicalities of the following

required conditions:

! existence of a reasonably efficient and regular collection system;

! existence of selective collection for domestic, public and medical waste;

! existence of a market for recyclables and compost in the region;

! availability of sufficient space to establish a segregation plant and/or composting

area;

! availability of resources to finance initial investment;

! availability of personnel with sufficient technical training to select appropriate

technology, supervise the setting up of a plant, maintain machines and supervise

their operation.

When determining which machines to install it should always be taken into account

that the more sophisticated and automatic they are, the higher the initial investment

and maintenance costs and the lower the level of employment generation.


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In Latin American and Caribbean countries, where there is high unemployment, labour

intensive systems are recommended such as manual segregation plants.

A considered economic feasibility study of any proposed project should be undertaken

taking into account on the one hand the advantages of installing a plant (reduction of

the amount of waste to be transported and buried, sale of compost and recyclable

material, generation of incomes and employment, environmental benefits), and on the

other, the implementation, operational and maintenance costs.

ECONOMICFEASIBILITY STUDIES

Prior to the establishment of a segregation or composting plant an economic feasibility

study should be carried out covering the following points:

Investment

! environmental licenses;

! purchase and legalization of land;

! architectural and engineering planning and works;

! purchase of machines and tools;

! capital expenditure (interest and amortization) and depreciation.

Expenditure

! personnel (non-qualified labour; technical, management and administration teams);

! operation and maintenance;

! energy and tariffs of public service concessionaires;

! spare parts and machine replacement.

Income

! direct

! sale of compost and recyclable material.

! indirect

! savings through the reduced cost of transport to the sanitary landfill;

! savings through reduced sanitary landfill costs resulting from reduced

waste volumes.

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Segregation and composting plants generate income and employmentand reduce the amount of waste to be disposed of in sanitary landfills

or refuse dumps.

The use of recyclable material results in a saving of energy andresources that would otherwise be used in the transformation of rawmaterials and this, together with the transformation of organic matterseparated from waste into compost that improves agricultural soils,represents a significant environmental and economic benefit from

segregation and composting plants.

Environmental

! energy savings;

! natural resource savings;

! reduced environmental contamination from waste.

Social

! provision of dignified and formal employment for segregators – the participation of

segregator organizations in plants should be prioritized whenever possible;

! income generation;

! promotion of public environmental awareness.

It is unlikely that the direct income from a segregation and composting plant will cover

its expenditures and the project should not be entered into as a profitable undertaking

from a strictly commercial perspective. However, taken as a whole, it can be seen as

being extremely positive when indirect income and the potential for significant

environmental and social benefits are considered.

RECYCLABLEMATERIALS MARKET

The market for recyclable material is growing rapidly and offers significant rates of

return, although there has been a concomitant increase in quality requirements.

Companies that buy recyclables impose three basic conditions:

! sufficient production scale;

! regularity of supply;

! good quality material.


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Materials that are appropriately segregated, relatively clean, and so more valuable, are

easier to commercialize in the market.

The commercialization of these products, including the sale price and production flow,

depends on the existence of local recycling companies that are interested in them.

Market prices vary and are directly influenced by the price of raw materials as well as

other factors such as the level of demand from recycling companies for a particular

recyclable material at certain periods of the year.

Some segregator cooperatives seek ways of increasing the value of their recyclable

material by for example endeavouring to make it as clean as possible and at least

segregating and baling the different types of paper and cardboard, aluminium cans and

hard plastic. They will also endeavour to sell directly to companies, eliminating intermediary

agents. Another fundamental requirement is to have a storage place for the materials

in order to rationalize their transport to the customer and be able to offer larger

amounts of recyclable material and in consequence obtain better prices.

12.3 Treatment of special domestic waste

12.3.1 Construction rubble

The most common treatment of construction rubble is its segregation, cleaning and

grinding for reuse in the construction industry itself.

Recycled rubble can be used in the base and sub-base of roads or as gross aggregate

in construction works, reinforced concrete works of art and pre-moulded elements.

The recycling of construction rubble has the following advantages:

! a reduction in the extraction of raw material;

! the conservation of non-renewable raw material;

! an improvement in the urban environment due to reduced indiscriminate dumping

of construction rubble in the streets;

! the availability on the market of cheaper construction materials;

! the creation of employment for unqualified labour.

The establishment of recycling plants for this type of material should therefore be

fostered and the possibility of charging special tariffs should be considered to ensure

their economic viability.

Three factors should be analyzed in a pre-establishment evaluation for a rubble recycling

plant in a particular location. In order of importance they are:

Demographic density – a high demographic density in the area is essential to ensure

a constant supply of rubble to the recycling plant.

Availability of natural aggregate – a scarcity of, or difficult access to, natural

deposits of raw material favours rubble recycling. However an abundance of, and

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Figure 98 - Rubble recycling plant - basic features

1 - Administration2 - Control centre3 - Entry checkpoint4 - Feeder5 - Grinder6 - Conveyor belt7 - Rubble to be recycled8 - Storage Area9 - Reception Area

10 - Green Belt11 - Garden

easy access to, natural deposits does not necessarily exclude the viability of rubble

recycling.

Technical level – it is necessary to use appropriate technologies to avoid environmental

degredation.

The location of a recycling plant on the periphery of an urban area is of fundamental

importance in order to keep the final cost of the recycled product down. Also, the

following factors should be studied:

In connection with rubble received:

! rubble characteristics (quantity, type and quality, place of origin, responsible

agent, regulations in force);

! demolition and renovation (techniques applied, rubble transport);

! collection and final disposal possibilities (prices, distances, existing local

regulations);

! processing (feasibility, technical team, organization and machines).

In connection with commercialization:

! natural raw material (quality, price, reserves);

! market conditions (type, current consumption, standards);

! recycled material (technical quality, quantity, price).


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Figure 99 - General view of a rubble recycling plant

Construction rubble recycling can be done in two ways: automatic and semi-automatic.

The automatic process employs a robust machine of great potency, able to receive

and grind construction rubble without the prior separation of iron rods that therefore

remain inside concrete blocks. After being ground the material passes through a

magnetic separator to remove ferrous material, which is pressed, baled and

commercialized. The rest of the material passes through a revolving sieve that

segregates it according to granulometric characteristics.

In the semi-automatic process iron is separated before grinding.

The plant should receive only inert waste so that there is no possibility of releasing

contaminating substances. The appropriate procedures and control devices should be

adopted to avoid the emission of particles.

The grinder feeder should be equipped with water sprinklers to minimize the emission

of dust and a rubber lining to keep noise levels within the limits established by

environmental control bodies.

Operational sequence for a semi-automatic plant

! rubble brought in by collection trucks is weighed on the recycling plant’s weighbridge

and sent to the reception area;

! in the reception area it is superficially inspected to determine whether the load is

compatible with the grinder. If it is not of an appropriate type, the unloading of the

vehicle will not be allowed and it will be sent to a sanitary landfill;

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Figure 100 - Rubble recycling plant - feeder and grinder

! if the material is compatible with the machinery the vehicle unloads in the reception

area. Manual segregation takes place there, separating out material of no use such

as plastic, metal and small amounts of organic matter;

! during manual segregation a mechanical loader is used to stir the material and facilitate

the work of segregators;

! the separated out material is categorized into what can be commercialized (scrap

iron) and what is for disposal (the rest of the material), and is put in separate areas

for storage and future disposal respectively;

! material with larger dimensions than those of the feeding mouth is not accepted,

nor concrete blocks with internal iron rods that can damage the mill by breaking the

hammers. In some cases reception area workers can break the blocks and separate

out the iron;

! material in which significant amounts of plastic are incorporated must never be

admitted as it can damage the machines;

! rubble from small construction works often arrives in bags and is manually unpacked

before the feeding and grinding operations;

! once material that is of no use has been removed, the rubble is lightly dampened by

a sprinkler system in order to minimize the dust generated during grinding. A mechanical

loader then places it in the feeder, which regulates its entry into the grinder.

! from the feeder the material passes to the mill where it is ground. From the grinder

the material moves along a small conveyor belt equipped with a magnetic separator

to separate iron that was not seen during the manual segregation and was introduced

into the impact mill;


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Figure 101 - Rubble recycling plant - grinder and conveyor belt

! later the material passes to the vibratory sieve that segregates it according to

predefined granulometry;

! each type of material is transported to its respective storage area on a conventional

constant speed conveyor belt.

Conveyor belts are mounted on wheels so that they can be moved sideways in a semi-

circle in the storage area. This facilitates direct transportation to the storage area in an

interrupted operation that avoids the need to move piles of ground material with a

mechanical loader.

The conveyor belt wheels should move on a concrete surface strong enough to support

its weight. The sideways movement of the belt is a manual operation carried out by

storage area workers each time that the pile of ground rubble reaches the maximum

height allowed by the incline of the belt.

In the storage area the ground material should always be kept damp to avoid scattering

by the wind and dust generation.

Vehicles that take ground rubble away are loaded with a mechanical loader similar to

the one used in the reception area.

Products made with recycled rubble include:

! pavement paving slabs;

! road sub-base and base;

! breeze blocks for cheaper housing walls and masonry;

! fine aggregate for surfacing;

! aggregate for storm drain inlet, kerb and gutter construction.

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The costs presented here are based on the establishment and operation of a large

automatic rubble recycling plant with a 100 ton/hour production capacity located 10km

from the urban perimeter:

! cost of the plant (construction work + machines): US$ 1,091,274.33

! unit production cost: US$ 10.30/ton

The establishment and operational costs for a semiautomatic plant are as follows:

A 120 ton/day capacity plant:

! investment costs: US$ 45,000.00

! construction work: US$ 25,000.00

! maintenance/operation: US$ 11.50/ton

A 240 ton/day capacity plant:

! investment costs: US$ 80,000.00

! construction work: US$ 30,000.00

! maintenance/operation: US$ 13.60/ton

12.3.2 Tyres

Problems caused by the inappropriate disposal of tyres in wasteland, watercourses

and streets, especially in peripheral urban areas, are a source of growing concern for

public authorities due to their significant environmental impacts.

Due to climatic conditions and other characteristics particular to Latin American and

Caribbean countries, the problem is of equal concern from a public health perspective

as inappropriately discarded tyres become a shelter and breeding ground for disease

vectors due to the water that accumulates in them.

In the United States, where the consumption of tyres is equivalent to one tyre per

inhabitant per year (approximately 300 million tyres a year), the most common treatment

is burning in thermoelectric plants. However due to difficulties involved in this process

it is applied to no more than 5% of used tyres.

In both the 100 million dollar Modesto plant in California, which burns 4.5 million tyres

a year generating 15 megawatts and providing energy to 14,000 houses, and the Sterling

plant in Connecticut, which burns 10 million tyres a year generating 30 megawatts,

operational costs are double those for coal burning plants.


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5 . A network of locations with the minimum infrastructure necessary for the reception and storage of unusable tyres that, when apredetermined number have accumulated, are then taken away by the private sector to be recycled.

The disposal of used tyres in sanitary landfills is inappropriate as there are operational

problems involved in burying them and they provoke empty spaces that cause points

of instability in the mass of waste. Consequently alternatives have been sought to

address this problem but up to now no definitive solution has been found.

This problem came to the fore in Brazil in the mid 1990s when the annual tyre

production had reached 35 million. At the end of that decade CONAMA introduced a

requirement obliging tyre companies to take responsibility for the disposal of waste

resulting from their production (used tyres) under the “polluter pays” principle. Burning

in cement industry clinker furnaces was the immediate solution that producers turned

to. However not all furnaces were adapted to burn tyres and there were some restrictive

factors associated with the procedure because of a change in the quality of the cement

produced and the emission of gases not in compliance with limits established by

environmental bodies.

In recent years the ongoing search for new technological processes has seen

developments such as one in Brazil that uses organic solvents to separate rubber

from the wire and nylon in tyres facilitating its recovery and recycling. However, many

of these new developments are not economically viable.

In spite of these efforts the problem continues and, as in other situations, it is the

urban cleaning system that has to bear the significant expenditure involved in dealing

with used tyres habitually discarded in unpopulated peripheral areas as it has an

obligation to collect them for sanitary and environmental reasons.

In this context, an initiative that can serve as an example for other urban cleaning

bodies in Latin American and Caribbean cities is the COMLURB “ecotyres” experience

in Rio de Janeiro.

Concerned with the growing number of used tyres discarded in the city, a study was

carried out on the route taken by tyres from their moment of purchase in different

neighbourhoods of the city to the moment when they are discarded, in general in

peripheral zones.

The study found this route to be: producers, dealers, recovery agents and tyre work-

shops. Tyres without any further possibility of use are discarded on wasteland, in

drainage channels or are burned.

This data led to the following measures: the registering of all locations, both formal

and informal, where tyres are repaired; the implementation of the “ecotyres” system 5

in cooperation with the private tyre sector; and the development of an information

program on the use of the “ecotyres” system covering dealers, tyre mechanics, bus

companies and haulage companies.

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The public authority should introduce specific regulations that consolidate the

application of the “polluter pays” principle by establishing the responsibilities of

producers and distributors for waste generated when their products are discarded.

12.3.3 Batteries and fluorescent tubes

The number of batteries present in domestic waste continues to increase as the use

of electrical and electronic gadgets spreads in modern society and plays an increasing

role in people’s daily lives.

The incidence of this type of waste in the overall composition of domestic solid waste

is clearly dependent on the socioeconomic condition of the population as here the

relation between consumption and disposal is direct. In Latin American and Caribbean

countries the problem has therefore yet to reach the concerning proportions that it

has in the United States, Japan and European countries.

However immediate action is necessary to establish control mechanisms for this

type of waste as it should receive the same level of treatment as hazardous industrial

waste.

Fluorescent tubes fall into a similar category and due to their high level of toxicity,

together with the difficulties involved in controlling environmental contamination

from them, they should be dealt with in the same way as toxic waste.

In the cases of both batteries and fluorescent tubes specific legislation is required

to consolidate the “polluter pays” principle. Under such legislation responsibility

for the treatment and final disposal of these types of waste would be assigned to

producers, with the participation of dealers and distributors in the reception of

discarded material and of the general public in separation, appropriate storage and

delivery.

12.4 Treatment of waste from special sources

12.4.1 Industrial solid waste

It is usual to treat industrial waste with a view to its reuse, or at least to leaving it inert.

Due to its diversity however there is no pre-established universally applicable process

so research and development for economically viable processes is always needed.

This waste should not be the responsibility of the urban cleaning authorities but of

the waste generators themselves, the industrial companies that produce it. Such an


185

approach requires comprehensive legislation and effective supervision mechanisms

to avoid irregular disposal of the waste.

Recycling and recovery

In general there is a trend towards transforming waste into base material for other

processes, thus generating savings in the industrial process. However transformation

processes require significant investment and offer unpredictable returns as the scope

for corresponding charges on the price of the product is limited, but this risk reduces

as technological developments provide more secure and economical ways of using

the material.

To encourage waste recycling and recovery, some states issue free periodical

publications in which industrial companies anounce waste that they have for sale or

donation, or waste that they want to purchase.

Other treatment processes

The most common treatment processes are:

! neutralization – for waste with acid or alkaline characteristics;

! drying by mixing – the mixing of waste that has a high humidity content with dry

waste or inert material such as sawdust;

! encapsulating – the lining of waste with a coat of impermeable synthetic resin with

a very low leaching level;

! incorporation – the adding of waste to a mass of concrete or clay in a proportion

that does not damage the environment, or the adding of it to combustible material

where gases that are harmful to the environment will not be generated during

burning;

! thermal destruction – incineration and pyrolysis.

12.4.2 Radioactive waste

There are still no economically viable treatment processes for radioactive waste. Atomic

stabilization processes for radioactive material have been developed but still cannot

be used on an industrial level.

As has already been explained this type of waste is the responsibility of a specialized

national body that operates within international regulations and safety procedures,

without any participation by the urban cleaning sector.

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12.4.3 Port and airport waste

This type of waste is not usually treated in a special way except in the case of

waste generated on boats or planes coming from regions where a particular disease

is endemic. In such cases it is important that the work of the urban cleaning team

is integrated with that of the professionals responsible for sanitary vigilance so

that appropriate sanitary and environmental procedures can be applied to the

storage, collection, treatment and final disposal of this waste. Incineration, or

another equivalent treatment, is usually recommended for waste with a high

potential risk.

In general most waste generated on these sites has similar characteristics to domestic

waste and can be collected and sent to the same final disposal units.

12.4.4 Medical waste

There are many technical processes for the treatment of medical waste. Until a short

time ago the debate on medical waste treatments was between incineration and

autoclave treatment as many countries do not allow its disposal in septic tanks at

sanitary landfills.

Recent progress in environmental research led to the discovery of atmospheric

contamination risks in the incineration process and resulted in a requirement for very

expensive treatments of generated gases, which has imposed economic restrictions

on its use.

New technical processes have led to the development of several treatments that are

already available on the market. Irrespective of its technical basis any waste treatment

that is adopted should:

! reduce the biological content of waste in accordance with stipulated requirements,

that is, the elimination of bacillus stearothermophilus in the case of sterilization

and of bacillus subtyllis in the case of disinfection;

! comply with regulations established by the government’s environmental control body

for effluents and gas emissions;

! avoid the de-characterization of waste thus ensuring that it is recognizable as medical

waste;

! process sufficient volumes in relation to the capital and operational costs of the

system in order to be economically viable in terms of the local economy.

The available commercial processes that meet these fundamental requirements are:

incineration, pyrolysis, autoclave, microwave, ionizing radiation, electro-thermal

deactivation and chemical treatment.


187

INCINERATION

Incineration is a burning process in the presence of a high level of oxygen, through

which carbon based materials are decomposed, releasing heat and generating ashes as

residue. Normally the amount of oxygen used in incineration is 10% to 25% greater

than is necessary in the common burning of waste.

Correctly carried out waste incineration is also an effective means of reducing the

volume of waste and leaving it absolutely inert in a short time. However installation and

operational costs are generally high principally because of the need for filters and

sophisticated technological devices to reduce or eliminate the contamination of the

air with gases produced during the burning of waste.

Basically an incinerator consists of two combustion chambers. In the first chamber

solid and liquid waste is burned with a high level of oxygen at a temperature of

800ºC to 1,000ºC, transforming it into gases, ashes and scoria. In the second chamber

gases produced by the initial combustion are burned at a temperature of 1,200ºC

to 1,400°C.

Gases resulting from the secondary combustion are rapidly cooled to avoid the re-

composition of their extensive toxic organic chains and are then treated in washers,

cyclones or electrostatic precipitators, before being discharged into the atmosphere

through a chimney.

As the waste burning temperature is not high enough to melt and volatilize metals,

they become mixed with the ashes from where it is possible to separate and recover

them for commercialization.

In the case of toxic waste that contains chlorine, phosphorus or sulphur, gases not

only need to remain for more time inside the chamber (approximately two seconds)

but also require treatment by sophisticated systems before they can be discharged

into the atmosphere.

In the case of waste composed exclusively of carbon, hydrogen and oxygen atoms all

that is required is an efficient system to filter particles expelled together with the

combustion gases.

There are different types of incineration furnace, the most common being fixed grate,

moving grate and rotary kiln.

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Figure 102 - Fixed grate incinerator

Overhead crane

Feeding

Collectiontruck

Airblower

Receptionpit

Fixed grate

Ash outlet

Combustionchamber

Contaminationcontrol

equipment

Ash outlet

Airextractors

Chimney

Fixed grate incinerators

In this process waste is deposited on a fixed grate where it is burned. Air is introduced

from above the grate to minimize the trailing of ashes. Ashes and scoria resulting from

the burning process fall through the holes of the grate into an ash pit, from where

they are removed mechanically or by water.

To ensure the level of oxygen necessary for the complete combustion of waste

and gases, the air flow is augmented by an extractor located at the base of the

chimney.

Moving grate incinerators

The grate consists of stepped cast iron sheets connected to a hydraulic system for

moving it in a swaying motion that conducts the waste from the access door through

to the ash and scoria pit.

The combustion grate is divided into three sections, the first one is for drying and the

waste is completely burned in the second and third sections.

Air for combustion in the furnace is provided by two blowers, one that blows air

amongst the waste (air below fire) and the other that introduces air above the waste

(air above fire).

Hot ashes and scoria from the burning are continuously deposited in a pit located

under the furnace from where they are removed mechanically or by water.


189

Figure 103 - Moving grate incinerator

Figure 104 - Rotary kiln

Overheadcrane for

bulky waste

Swayinggrate

Ventilationblower

Overhead craneto transport waste

Overhead craneto transport ashes

Steamcontrol valve

Use of heat generatedby waste

Steam turbine Condensationtank

Chimney

Heater

Furnace

Reagentcatalyticreactor

CondenserGas

re-heaterFiltersleeve

Gas cooler

Bulkywaste pit

Waste pit Conveyor beltfor ashes

Fly ashtreatment

Ash pit

Gaswasher

Ventilationblower

Bulkynon-combustible

wasteMagnetic separator Rotary

sieveBulky combustible waste

Hammergrinder

Aluminiumseparator Ground

combustiblematerialFerrous

material pressAluminium

pressFerrous

material storageAluminium

storage

Slow speedblade grinder

Collectiontruck

Feedersystem

Liquidwaste burner

Rotarykiln

Heatinterchanger

Electrostaticfilters

Gaswasher

Washer -water

oxidation

Chimney

Airextractor

Receptionpit

Post-burningchamber

with chimney

Rotary kiln

Rotary kilns are useful for the thermal destruction of infectious waste but are more

used for burning hazardous industrial waste. They are cylindrical incinerators with a

diameter of approximately four metres and a length of up to four times the diameter,

mounted with a slight incline in relation to the horizontal plane.

The entrance is at the higher end, the opposite end to the burners, so that the waste

moves slowly downwards due to the rotation of the cylinder.

Gases generated pass to a secondary burning chamber that accommodates burners

for liquids and gases. Gases resulting from this burning flow into heat interchangers

and washing equipment.

190

Figure 105 - Pyrolytic furnace

Primary air

TemperatureGradient

Drying

Decomposition

Gasification

,

Ash extractor

Secondary air

Cyclone BoilerAir extractor

PYROLYSIS

Like incineration, pyrolysis is a thermal destruction process with the difference that it

absorbs heat and takes place in the absence of oxygen. In this process, carbon based

materials de-compose into combustible gases or liquids and carbon.

Pyrolytic furnaces are very much used in the treatment of medical waste, where the

calorific value of the waste maintains a certain temperature during the process.

There are single chamber models where the operating temperature is approximately

1,000ºC and dual chamber models with temperatures of between 600ºC and 800ºC in

the primary chamber and between 1,000ºC and 1,200ºC in the secondary chamber.

The feeder system can be automatic (continuous) or semi-automatic (by lots) and the

auxiliary burners can burn diesel or gas.

Its main advantages are:

! effective treatment is guaranteed given optimum operational conditions;

! substantial reduction in the volume of waste to be disposed of (almost 95%).

Its main disadvantages are:

! high operational and maintenance costs;


191

Figure 106 - Medical waste incineration plant with a capacity of 250kg/hour

! maintenance difficulties requiring constant cleaning work in the auxiliary fuel feeder

system, unless natural gas is used;

! high risk of air contamination from dioxins generated by the inappropriate burning

of chloro materials present in PVC bags and disinfectants;

! risk of air contamination due to the emission of particulate matter;

! high cost of effluent treatment.

It should be noted that neither incineration nor pyrolysis completely solve the medical

waste final disposal problem as both the ashes that are produced and the sludge

resulting from the treatment of gases require an appropriate final disposal.

AUTOCLAVE

Originally used for the sterilization of surgical equipment, this process was adapted

and developed for waste sterilization.

Basically it consists of a feeder system that conveys the waste into a hermetic chamber

where a vacuum is created and steam is then injected (from 105ºC to 150ºC) under

certain pressure conditions.

192

Figure 107 - Autoclave

The waste remains in the chamber for a certain period until it is sterile, after which

water is discharged from one side and the waste from the other.

Advantages:

! relatively low operational costs;

! does not emit gases and effluent is sterile;

! relatively easy and cheap maintenance.

Disadvantages:

! there is no guarantee that the steam will reach all parts of the mass of waste unless

it has been appropriately ground before the sterilization phase;

! does not reduce the volume of waste unless it is previously ground;

! waste is processed in lots, continuous treatment is not possible.

MICROWAVE

In this process waste is ground, dampened with steam at 150ºC and is fed, as a

continuous process, into a microwave furnace where there is a device to stir and

transport the mass so that all of the material uniformly receives the microwave radiation.


193

Figure 108 - Microwave

Advantages:

! absence of emissions or any type of effluent;

! continuous process.

Disadvantages:

! relatively high operational costs;

! the volume of waste to be buried is not reduced unless it is ground.

IONIZING RADIATION

In this process, waste in its natural form is exposed to the action of gamma rays,

generated by a source of enriched cobalt 60, which render micro organisms inactive.

This process has the following disadvantages in comparison with previously mentioned

processes:

! treatment effectiveness is questionable as a possibility exists that part of the mass

of waste is not exposed to the electromagnetic rays;

! the used cobalt 60 source (radioactive) requires appropriate disposal.

Its advantages are the absence of any type of effluent emission and the fact that it is

a continuous process.

194

Figure 109 - Ionizing radiation

Weighbridge

Automaticdoors

Receptionpit

Deodorizer Deodorizer

HEPA Filter -Pre-filter

Dustcollector

Hydraulicpress

HEPA Filter -Pre-filter

Primary grinder -primary cyclones

Secondary grinder -secondary cyclones

Liquids

Waste reception Grinding and homogenization

Processingunit

PressControlpanel

Container

Transport

Treatment

To thelandfill

Class Cwaste

ELECTRO-THERMALDEACTIVATION

This process consists of double grinding prior to treatment, followed by the exposure

of the ground mass to a high potency electrical field, generated by low frequency

electromagnetic waves, reaching a final temperature of 95ºC to 98ºC.

In this process there is no effluent or gas emission.

The advantages and disadvantages of this process are the same as those for the

microwave process, with the addition of equipment maintenance difficulties, and there

is no volume reduction unless a post-treatment grinding system is installed.

CHEMICAL TREATMENT

In this process waste is ground and then submerged in a disinfectant solution that

can be sodium hypochlorite, chlorine dioxide or formaldehyde gas. The mass of

waste remains in the solution for some minutes and the treatment is by direct

contact.


195

Figure 110 - Chemical disinfection

Grinder Nº 1

Bags ofmedicalwaste

Feeder

Sodiumhypochlorite

solutionIm

mersion

Inclin

ed sc

rew co

nvey

or

Pulverizer Nº 1(disinfectant)

Mixer

Pulverizer Nº 2(disinfectant)

Gas washing

Particlefiltering

Air extractorHEPA filter

Vapo

ur

Horizontal screw conveyor

Verti

cal s

crew

con

veyo

r

Discharge tube

Rotary dischargescrew conveyor

½ to 2 inchgrater (dry)

Grinder Nº 2

½ to 2inch grater

Before being deposited in the outlet container, waste passes through a drying system

generating an environmentally harmful effluent that has to be neutralized.

The advantages of this process are its low operational and maintenance costs and the

effectiveness of the waste treatment.

The disadvantages are the need for effluent neutralization and the absence of volume

reduction unless the waste is ground, which would have to be a separate process.

196

Solid waste final disposal13

13. Solid waste final disposal

197

13.1 Introduction

Urban cleaning systems have to face the challenge not only of collecting solid waste

from streets and buildings in ever-growing cities but also of ensuring an appropriate

final destination for such waste.

The latter issue deserves attention because if collection is inefficient public pressure

is put on the municipality to improve service quality due to it being an exposed and

visible activity, while if the final disposal of waste is carried out in an inappropriate

way, few people will be directly disturbed by this and so it will not generate complaints.

Consequently, as many municipalities in Latin America and the Caribbean have a limited

budget, the urban cleaning system will tend to leave final disposal in the background

giving priority to waste collection and street cleaning.

As a result in many municipalities, particularly the smaller ones, it is common to find

refuse dumps where collected waste is deposited directly on the ground without any

supervision or environmental care, contaminating soil, air, the water table and

neighbouring land.

In addition to the sanitary and environmental problems that refuse dumps present,

there are serious social problems connected with the segregators that they attract.

These people make their living from the separation of recyclable material and often

live in huts and shacks on the site of the dump, raising families and even forming

communities.

The only appropriate form of solid waste final disposal is in sanitary landfills or, provided

certain conditions that will be described later are fulfilled, in controlled landfills. All the

other processes that are regarded as disposal (recycling, composting and incineration

plants) are in reality waste treatment processes that need a landfill for the final disposal

of the remaining waste.

The initiation of a sanitary landfill presents difficulties not only because it involves

environmental studies, specific sanitary engineering and environmental planning and a

relatively high initial investment before it is established, but also due to the natural

resistance that arises in people when they know that they will be living close to a place

where waste will accumulate.

This rejection stems from a perception that society has of solid waste disposal sites

as being inadequately set up and badly managed. It is therefore necessary to defeat

this stigma through thorough studies and project planning, and with a broad awareness

raising process in society that communicates the difference between sanitary landfills

and dumps. At the same time, it is essential that the political will exists to allocate the

necessary budgetary resources for the implementation and correct operation of the

approved project.

198

13.2 Impacts of inappropriate solid waste disposal

Problematic situations often encountered around the site of incorrect municipal solid

waste disposal and their respective consequences are:

! proximity to bodies of water ! water contamination;

! lack of covering, or only partial covering, of waste ! vector proliferation, odours,

unsightliness and landscape contamination;

! practice of burning waste ! safety risks for people, atmospheric contamination,

energy wastage;

! lack of physical barriers (areas without fences) and a vegetation belt ! access for

people and animals, dispersion of odours and waste particles;

! inappropriate disposal of medical waste mixed with domestic waste ! increased

risk to people and of environmental contamination;

! pig raising and presence of other animals ! zoonosis and other public health risks;

! proximity to population centres, educational centres and kindergartens !

inhabitants subject to various nuisances and sanitary risks;

! segregation activities carried out by women, men, old people and children !

citizenship degradation, exposure to unhealthy conditions, health risks and accidents;

! proximity to environmentally protected areas (ecological reserves and equivalents)

! degradation of the area and environmental contamination risks.

Landfills are a kind of melting pot for chemical and biological activity and reactions that

produce effluents, the nature of which depends on the components of the waste,

hence the previous segregation of special waste is indispensable.

At the final disposal site the biological decomposition of the remains of food and

other organic material contained in domestic waste generates an effluent with a high

BOD (biochemical oxygen demand) that moves and incorporates other substances

contained in the mass of waste. As a result this leachate is highly contaminating due to

its high BOD and chemical reactions between its components (heavy metals, for example).

In addition domestic solid waste anaerobic decomposition processes generate biogas,

principally composed of methane, which is explosive in concentrations of 5% to 15% in

the air. Biogas is not only toxic but is one of the contributory factors to the greenhouse

effect. The composition of this biogas includes gases with an unpleasant smell such as

hydrogen sulfide and mercaptans.

Measures to avoid the negative effects that result when waste is inappropriately disposed

of on the ground should include the creation of an environment less favourable for


199

undesirable chemical and biological reactions. It is therefore necessary to isolate or

minimize the contact between waste components that could react with each other.

Finally it is necessary that effluents and gases are dealt with in an appropriate way.

A solid waste final disposal project should therefore incorporate technical solutions

that comply with the basic guidelines for avoiding the above mentioned environmental

impacts.

In a solid waste final disposal unit the soil is the principal receptor and conductor of

contaminants. Nevertheless it can also serve as protection against the contamination

of underground water and the environment provided that it is sufficiently deep and

impermeable. Where these favourable conditions do not exist naturally, engineering

resources should be used to comply with the required technical specifications and

applicable regulations.

The recommended method for domestic waste final disposal is the sanitary landfill. In

Latin American and Caribbean countries an acceptable alternative for smaller

municipalities with limited economic resources is the controlled landfill, which can be

used provided that technical and environmental norms established by regulatory legal

instruments are respected.

13.3 Sanitary landfill

The objectives and principles of sanitary landfill construction and operation can be

defined in different ways. In our opinion the most appropriate definition is the one

established by the Sanitary Engineering and Environmental Sciences Pan-American Centre

(CEPIS, in Spanish), of the Pan American Health Organization, which has been

incorporated in many technical norms and adopted by environmental bodies and entities.

It states that:

“The sanitary landfill is a technique for the final disposal of solid waste in the ground

that causes no nuisance or danger to public health or safety; neither does it harm the

environment during its operations or after its closure. This technique uses engineering

principles to confine the waste to as small areas as possible, covering it daily with

layers of earth and compacting it to reduce its volume. In addition, it anticipates the

problems that could be caused by the liquids and gases produced by the decomposition

of organic matter.”

A sanitary landfill unit of construction is called a cell, in which each day’s solid waste

(or the waste from a shorter period if the daily amount of waste is too great) is deposited

in compacted sloping layers and is covered with a layer of earth that is also compacted.

The cell is built against a retaining wall that can be a pre-existent natural elevation, a

berm previously formed with compacted earth or other cells. Cells are constructed

next to each other, each one supported by the previous one, forming a “landfill level”;

the landfill can have two or more levels, depending on project requirements.

200

Figure 111 – Construction of the operational area - Embankment

Figure 112 – Waterproofing of the operational area

When determining the dimensions of a cell, some basic criteria should be taken into account:

! the width of a cell’s work face should not be greater than is necessary for the safe

manoeuvring of machines and vehicles;

! the height should be between 3 and 6 metres depending on the amount of waste

to be dealt with (sanitary landfill capacity);

! the advance should be calculated according to the daily volume of waste, the width

of the work face and its height;

! dimensions are adjusted according to the stability and availability of the land.

A sanitary landfill consists of operational and support units.

Operational units

! domestic waste cells;

! medical waste cells (where the municipality does not have a more effective final

disposal process for this type of waste);

! waterproofing of the bottom (obligatory) and of the top (optional);


201

Figure 113 – Leachate collection and treatment

Figure 114 – Biogas collection and burning

Figure 115 – Rainwater drainage system

! collection and treatment system for percolated liquid (leachate);

! biogas collection and burning (or use) system;

! rainwater drainage and channelling system;

202

Figure 116 – Storage area for materials

Figure 117 – Vegetation barrier

Figure 118 – Preparation of an internal service road

! environmental, topographical and geotechnical monitoring systems;

! storage area for materials.

Support units

! fence and vegetation barrier;

! access and service roads;


203

Figure 119 – Weighbridge for weighing loads

Figure 120 – Support units

! weighbridge for trucks and waste checkpoint;

! entrance checkpoint and administrative offices;

! mechanical and tyre workshops.

The sanitary landfill pre-operational process consists of the selection of the site,

obtaining the necessary licenses, formulating the project master plan and installation.

13.3.1 Sanitary landfill site selection

The selection of the sanitary landfill site is a complex task. The intense urbanization

and land use in cities limits the availability of sites that are both close to where waste

is generated and large enough for the installation of a sanitary landfill that will meet

the needs of the municipality.

Many other factors have to be taken into account such as the technical requirements

of the norms and guidelines issued by relevant public bodies, juridical aspects,

204

governmental requirements, the governing plan of the corresponding municipality, local

and regional development centres, the distance over which waste will have to be

transported, access roads and political and social aspects involved in the approval of

the project by politicians, the media and the community.

Economic and financial factors must be a major consideration as municipal resources

always have to be used in a balanced way.

Requirements for the appropriate establishment of a sanitary landfill are therefore

very rigorous and it is necessary to carefully define an order of priorities.

The selection strategy for a new sanitary landfill site consists of the following steps:

! preliminary identification of land available in the municipality;

! determination of all selection criteria;

! definition of the selection criteria order of priority;

! a critical analysis of each potential site in relation to the prioritized criteria, so that

the site that most complies with the required conditions in terms of its natural land

characteristics is selected.

Applying this strategy minimizes the corrective measures that have to be taken to

adapt the land to technical requirements and thus reduces the need for initial

investment.

PRELIMINARY IDENTIFICATIONOF AVAILABLE SITES

The preliminary identification of available sites in the municipality should be carried out

as follows:

! preliminary calculation of the total area needed for the sanitary landfill;

To make an approximate calculation of the minimum total area necessary for the

installation of a sanitary landfill, in square metres, some experts multiply the quantity

of waste collected daily, in tons, by the factor 560. This factor is based on the following

landfill project parameters:

Useful life = 20 years; landfill height = 20 m; slopes of 1:3 (vertical : horizontal) and an

80% operational occupation of the land.

However the operational usage as a percentage of the total area will depend on the

particular conditions of each site (topography, hydrology and geometric shape, for

example).


205

Table 17

Technical and legal criteria

Land use

Distance to

bodies of water

The site should be outside the limits of any environmental

conservation areas and in a zone where designated land

use is compatible with the operation of a sanitary landfill.

The site should be not less than 200 metres from major

bodies of water such as rivers, lakes, lagoons and oceans

and should be not less than 50 metres from any other

body of water.

Criteria Observations

! perimeter delimitation of rural and industrial zones and conservation areas existing

in the municipality;

! survey of the available sites within the delimited perimeters, where there are no

zoning or land use restrictions and sites have dimensions compatible with the

preliminary calculation, giving priority to land owned by the municipality;

! determination of ownership of surveyed sites;

! study of documents relating to the sites, excluding those where the documentation

is not in order.

It is very important that the legal situation in relation to the ownership of a site is in

order to avoid potential problems for the municipality and delays in the licensing process.

SELECTION CRITERIA

The criteria are divided into three groups: technical and legal, economic-financial, and

socio-political.

Technical and legal criteria

The selection of a sanitary landfill site for domestic solid waste final disposal should

fulfil the technical criteria imposed by technical norms and regulations stipulated by

the different levels of authority in each country.

All the conditions and restrictions commonly stipulated by technical norms and relevant

regulations are listed in table 17. It should be noted however that specific aspects of

legislation in any particular country may vary from the concepts and dimensions

described here, which in such cases should be appropriately modified.

206

Table 17 (cont.)


The site should be not less than 300 metres from urban

residential centres with 200 or more inhabitants.

The site should not be located in the proximity of airports

or aerodromes and should comply with current legislation

in this respect.

The minimum distances recommended are the following:

! in a sanitary landfill with plastic membrane water-

proofed bottom, the distance between the water table

and the membrane should not be less than 1.5 metres;

! in a smaller landfill the bottom of which is waterproofed

by a layer of compacted clay with a permeability coef-

ficient of less than 10-6cm/s, the distance between the

water table and the waterproofing layer should not be

less than 3 metres.

It is recommended that the site is compatible with a useful

life for the new sanitary landfill of at least 8 years.

It is recommendable that the soil of the selected site has

good natural impermeability in order to reduce the

possibility of aquifer contamination. The soil of the

selected site should be clayey.

The rainwater drainage basin should be small in order

to avoid significant amounts of rainwater entering the

landfill.

Roads leading to the site should not have pronounced

inclines or curves and should be well surfaced in order to

minimize wear and tear on collection vehicles and enable

them to have easy access even at times of intense rain.

It is preferable that the site has, or is close to, deposits

of material appropriate for covering, in order to keep the

cost of waste covering low.

Distance to urban

residential centres

Distance to

airports

Water table depth

Minimum

useful life

Natural soil

impermeability

Topography

favourable to

drainage

Easy access for

heavy vehicles

Availability of

material for

covering

The length of a sanitary landfill’s useful life is very important as it is increasingly difficult

to find new sites close to the collection area that are suitable for receiving the volume

of urban waste generated in the municipality. This is largely due to the natural rejection

of residents to having this type of waste final disposal unit close to where they live.


207

Table 19

Political and social criteria

Access to the site

through low

demographic

density areas

Local community

acceptance

The passage of vehicles transporting waste along residential

streets constitutes an inconvenience for the inhabitants of

those streets and it is therefore recommended that truck

routes to the sanitary landfill pass through areas of low

demographic density and preferably on roads designed to

handle heavy vehicles.

It is recommended that a site is not chosen if there have

been previous problems between the municipality and the

local community, non-governmental organizations (NGOs)

or the media in the area as any past disharmony with the

public authorities is likely to cause negative reactions to

the proposed landfill.


Table 18

Economic and financial criteria

Proximity to

collection area

Land purchase

costs

Construction and

infrastructure

investment costs

Drainage system

maintenance costs

The distance that collection vehicles have to cover on existing

roads and streets between the collection area and the sanitary

landfill should be as short as possible in order to minimize

wear and tear on trucks and waste transport costs.

If the land is not owned by the municipality, and therefore

has to be purchased, it is preferable that it is located in a

rural area where purchase prices are lower than in other

areas where the landfill could be sited (industrial areas for

example).

It is important that the selected site has access to service

infrastructures in order to limit expenditure on water

provision, collection and treatment of local effluents, rain

water drainage, electricity supply, and communications

facilities.

The selected site should have a gentle incline to avoid soil

erosion and limit expenditure on cleaning and maintaining

drainage system components.


Economic and financial criteria

Political and social criteria

208

Priority

Table 20

Criteria hierarchy

Compatibility with environmental legislation

Compatibility with political and social conditions

Compatibility with the main economic conditions

Compatibility with the main technical conditions

Compatibility with other economic conditions

Compatibility with other technical conditions

1

2

3

4

5

6

Criteria

Table 21

Weight given to criteria and compatibility

Priority of criteria

1

2

3

4

5

6

Weight

10

6

4

3

2

1

Total

Partial or total with work

No compatibility

100 %

50 %

0 %

Compatibility Weight

SELECTION CRITERIAORDER OF PRIORITY

Table 20 shows a suggestion for the selection criteria order of priority in choosing a

sanitary landfill site.

In order to determine which is the best site for the sanitary landfill, each candidate site

should be the subject of an exhaustive analysis in regard to each of the established

criteria. For each criterion the analysis should allocate one of the following categories

and provide reasons for doing so: “total compatibility”, “partial compatibility, or total

with work” or “no compatibility”.

Both the priorities and the compatibility with the defined criteria are given a relative

weight, as shown in table 21.


209

Note: T = Total compatibility; P = Partial compatibility; N = No compatibility.

Criteria PrioritySite 3

Site characteristics

Table 22

Compatibility

Site 2Site 1

Distance from bodies of water

Distance from residential centres

Distance from airports

Water table depth

Access through low demographicdensity areas

Acceptance by local community

Land purchase costs

Existence of infrastructure

Minimum useful life

Land use

Natural impermeability of soil

Favourable topography for drainage

Easy access for heavy vehicles

Coverage material availability

Drainage system maintenance

Proximity to collection centre

1

1

1

1

2

2

3

3

4

4

4

4

4

4

5

6

T

T

T

P

P

N

P

T

P

T

P

P

T

N

P

T

T

T

T

P

P

P

P

T

T

T

P

P

P

P

P

P

T

P

T

T

P

T

T

P

T

T

P

T

P

T

T

P

SELECTION OF THE BEST SITE

Analysis of candidate sites in relation to the established criteria

The site chosen for the sanitary landfill should be the one that is compatible with the

highest number of criteria, taking into account the relative priority of each one.

When the natural attributes of the selected site are not totally compatible with a certain

criterion, its deficiencies should be remedied by the application of modern engineering

solutions.

As an example we present the case of a municipality that has to determine which is the

best site amongst three pre-selected candidate sites, the characteristics of which are

shown in table 22.

The site with more points will be considered the best.

210

Criteria

Table 23

Site1

Compatibility

weightPoints for

each sitePriority

weight

Distance from bodies ofwater

Distance from residentialcentres

Distance from airports

Water table depth

Access through lowdemographic density areas

Acceptance by localcommunity

Land purchase costs

Existence of infrastructure

Minimum useful life

Land use

Natural impermeability ofsoil

Favourable topography fordrainage

Easy access for heavyvehicles

Coverage materialavailability

Drainage systemmaintenance

Proximity to collectioncentre

Points total

Points for each site

Site2

Site3

Site1

Site2

Site3

10 100% 100% 100% 10.0 10.0 10.0

10 100% 100% 50% 10.0 10.0 5.0

10 100% 100% 100% 10.0 10.0 10.0

10 50% 50% 100% 5.0 5.0 10.0

6 50% 50% 50% 3.0 3.0 3.0

6 0% 50% 100% 0.0 3.0 6.0

4 50% 50% 100% 2.0 2.0 4.0

4 100% 100% 50% 4.0 4.0 2.0

3 50% 100% 100% 1.5 3.0 3.0

3 100% 100% 100% 3.0 3.0 3.0

3 50% 50% 50% 1.5 1.5 1.5

3 50% 50% 100% 1.5 1.5 3.0

3 100% 50% 50% 3.0 1.5 1.5

3 0% 50% 100% 0.0 1.5 3.0

2 50% 50% 100% 1.0 1.0 2.0

1 100% 50% 50% 1.0 0.5 0.5

56.5 60.5 67.5

After the weighting process is applied, in accordance with table 21, the candidate sites

have the following points:

As can be seen, site 3, in spite of being located relatively close to a residential centre,

is the one that overall has the most advantages.


211

EIS is a technical study, undertaken by specialized companies, withthe objective of determining the positive and negative aspects of the

project in regard to the physical (climate, geology, hydrology,pedology, etc.), biotic (flora and fauna) and anthropic (related to

human activities) environment. It also establishes measures that canbe taken to avoid or diminish identified negative impacts.

After choosing the sanitary landfill site the municipality should not immediately proceed

with the purchase or compulsory purchase of the land as the project first needs

approval from the relevant environmental body, through a licensing process that is

based on deeper environmental studies.

13.3.2 Environmental licenses

The procedures for obtaining the necessary licenses for a sanitary landfill site depend

on formal processes and relevant legislation in each country.

The basic actions to take and process stages are presented here:

STAGE I

Approval of the land for landfill use

The objective of this stage of the environmental license application process is to

evaluate the selected site to determine whether it is appropriate for use as a landfill, in

comparison with other alternative sites.

The process begins with the presentation of a formal request by the applicant (the

municipality or private company, for example) to the relevant environmental body. This

document should be accompanied by general information about the site and the

conceptual basis of the sanitary landfill project.

Once the request is received, the environmental control body prepares technical

instructions (or terms of reference) in which the relevant aspects to be evaluated in

an Environmental Impact Study (EIS) are defined. The preliminary plan for the sanitary

landfill should be ready before this study is carried out.

As these studies are highly specialized, with complex methodologies and technical

terminology, a second report has to be prepared that presents a summary of the principal

finding of the EIS in a language that is accessible for the general public. Thus society in

general can form an opinion on the subject and participate democratically in the licensing

process.

It is important to note that environmental studies should be carried out with the

cooperation of technical teams from both the municipality and the environmental

control body, so that the methodology, technical guidelines and conclusions are, as

far as is possible, compatible with the policies of these entities.

212

Once completed, the studies should be immediately sent to the environmental control

body, which will analyze them and issue a technical opinion.

After this opinion is presented the community can be called to participate in public

hearings on the approval process, where this is the policy of the environmental control

body. In the specific case of a new sanitary landfill it is always advisable to hold such

public consultations.

EIS presentation at a public hearing should be accompanied by all available audio-visual

aids as the participating public will mostly be lay people who will better be able to

understand proposed solutions if they can see visual images of them.

Once the environmental impact study is approved, together with the pertinent palliative

measures, and after the necessary environmental impact compensatory measures are

established, the environmental control body will grant the authorization document

that licenses the selected site for the installation of a sanitary landfill. It should be

noted however that this license does not authorize the immediate commencement of

works, as first several complementary procedures have to be carried out by the applicant.

STAGE II

Authorization to commence sanitary landfill installation works

In the initial stage of the licensing process, and on the basis of the environmental

impact study, the environmental control body determines the conditions and restrictions

that the applicant has to comply with in order to obtain an environmental license to

commence sanitary landfill installation works.

The detailed engineering plan (master plan) should therefore take into account those

requirements and incorporate the concepts contained in the environmental impact

control and minimization plans recommended in the environmental assessment.

The compilation of field data must be completed in this stage, including detailed

topographical surveys and new geotechnical probes and tests. Detailed plans that deal

with environmental issues should also be completed, as should plans for layouts,

rainwater drainage, the collection and treatment of leachate, the collection and burning

of biogas, access and service roads, support unit buildings and landscaping.

The master plan should also include a detailed operational plan covering the operation of

the sanitary landfill, geotechnical and topographical monitoring, environmental monitoring,

weighbridge operation (if there is one) and machine, vehicle and equipment maintenance.

Finally detailed plans for foundations, superstructures, water and sanitation, electricity

supply, telephones, etc. are required.

Once completed, these plans should be submitted to the environmental control body

that will ascertain whether the requirements and conditions established when granting


213

the stage I license have been met. If they have, the environmental body will issue the

license that authorizes commencement of sanitary landfill installation works.

STAGE III

Authorization for commencement of sanitary landfill operation

Once the environmental license authorizing the commencement of works is obtained,

the master plan begins to be put into practice, that is, earth works, excavation, drainage,

access road construction, etc. is carried out.

In this phase the applicant has to take into account that works should be carried out in

a way that rigorously respects not only the engineering plan but also control plans and

programs resulting from the environmental impact study that conditioned the approval

of the project by the environmental control body.

Consequently, paying attention to the circulation of vehicles and machines during the

work, the regulation of the internal combustion engines and the dispersion of

suspended particles in the work area, amongst other aspects, should be part of the

daily routine of engineers, overseers and all professionals involved.

Fulfilling the relevant environmental requirements and installing systems and devices in

accordance with the project plans are essential for obtaining the environmental license

that will authorize the operation of the sanitary landfill. Therefore, in addition to covering

the work itself, planning should include an efficient and responsible environmental

management strategy.

13.3.3 Master plan

The sanitary landfill master plan should maximize the useful life of the available area,

fully utilizing the natural characteristics of the land, minimizing installation costs and

ensuring appropriate environmental monitoring and safeguards.

In general it takes from 90 to 120 days to formulate a sanitary landfill master plan,

which has to rigorously comply with technical norms and environmental legislation.

The master plan should include the following documents:

! planialtimetric plan for the landfill in an appropriate scale, with contour lines

representing each metre, and showing the location of accesses, plateaus,

constructions and other significant features;

! geotechnical research and test results;

! water quality analysis results for surrounding bodies of water and the water table;

214

! access and service roads plan, including layout, earth works, surfacing and drainage;

! construction plans, including the calculations for foundations and structures,

architectural design, landscaping and structures related to water and electricity

provision, communications, security and others;

! external network plans for water, sewerage, electricity and rainwater drainage

systems;

! layout plan for terraces, embankments and the final configuration of the sanitary

landfill and plans for each annual filling stage with cross sections;

! plans for the collection and treatment of leachate, including bottom and top

waterproofing layers (where applicable), bottom drainage network, pumping network

and treatment plant;

! superficial drainage plans for the landfill, including the slope of the platforms both

for the landfill’s intermediate stages and for the final stage, drainage of the definitive

berms, water drain pipes and discharge structures;

! delimitation plans of sanitary landfill plots;

! biogas collection and burning system plans, showing cross-sections and details;

! environmental monitoring plan, including water table monitoring wells;

! landfill operational manual covering the routine activities of solid waste disposal,

including leachate treatment plant operations and rainwater drainage network

maintenance;

! a record of the calculations made for landfill and construction stability studies,

construction structures, superficial and deep water drainage networks, electricity

and water installations, the biogas collection and burning network and quantification

of machine, vehicle and labour requirements for landfill operation and maintenance;

! technical specifications of all equipment, services and materials involved in the work;

! sanitary landfill closure plan, including post-closure environmental monitoring plan.

Once the master plan has been approved, it is essential that it is presented to the

community using simple and direct language and the best audiovisual aids, informing

citizens about the nature of a sanitary landfill, the contamination control measures

that will be taken, the benefits of appropriate solid waste disposal and the

compensatory measures applicable to residents of the area. Such an approach will

help to avoid problems during the installation and operation of the sanitary landfill.


215

A barrier of vegetation should be planted along the wire fence witha minimum width of 15 metres. The objectives of this are to blockthe line of sight to the operational area, contain airborne particles

and help to reduce the dissemination of characteristic wasteodours.

13.3.4 Landfill installation

When the master plan has been approved and authorization for installation has been

obtained, work on the landfill can begin with fencing, land clearing and constructing

the foundations for a weighbridge (where applicable).

Works should always comply with technical specifications and all the other conditions

set out in the master plan, as well as with the requirements of technical norms,

government bodies that establish employment and work safety policies,

environmental control bodies, environmental legislation and norms and directives

issued by public service concessionaires (water, electricity, telephone, fire control

and others).

In medium-sized and large landfills the sequence of construction is in general as

follows:

SITE FENCING

Site fencing is necessary to discourage the entrance of non-authorized people and

animals such as dogs, horses, cows or pigs. An approximately two metre high fence is

recommended made of concrete or wood posts and galvanized wire with small spaces

in the lower part so that small animals cannot enter.

INITIAL LAND CLEARING WORKS

This includes the removal of natural vegetation (clearing and stump removal) by cutting

trees, grass, bushes etc. and scrapping off the vegetation layer on operational areas

such as the landfill area that will receive domestic and public waste and the effluent

treatment plant area, wherever possible preserving landscape composition elements

even if this does not appear in the plans.

216

EARTH WORKS

Earth works should rigorously respect the plans for them and excess material from

cuts should be stored in an appropriate place to be used in the future as cover material

for landfill cells.

Layers that need to be compacted should be dampened until “ideal humidity” is achieved.

Earth works finish with the organization of the storage area for materials, which should

ideally be located close to the landfill operational area.

ACCESS AND SERVICE ROAD WORKS

Sanitary landfill access roads are categorized as external or internal and permanent or

temporary.

As has been previously explained, special attention has to be paid to the surfacing of

external access roads and their capacity to support heavy vehicles right from the stage

when alternative sanitary landfill sites are being evaluated. These roads have to be

easily passable in all seasons of the year and must have appropriate surfacing and

road signs so that they are safe for the heavy vehicles that will use them and for the

local residents. Road maintenance should be a priority in planning for the entire projected

operational life of the sanitary landfill in order to ensure the regular flow of collection

vehicles to the landfill and, therefore, sound sanitary and environmental conditions.

Internal access and service roads should be built with a primary surface of gravel or

selected rubble. They should have a uniform incline towards one side to direct rainwater

to a drainage system that runs along the side of the road.

In smaller landfills internal roads can have different types of surface: brick dust, gravel,

construction rubble or quarry products.

The recommended thickness for a landfill’s internal road surfaces is from 30 to 50cm,

compacted in layers of 15 to 25cm, depending on the volume of traffic and therefore

the landfill’s size.

WATERPROOFING WORKS

A 3m layer of clayey soil (k<10-7cm/s) between the bottom of the landfill and the top

of the water table provides an excellent protection against the contamination of

underground water. As a naturally occurring formation of this type is quite rare, a

technical solution that may be applied is the use of geo-membrane (plastic membrane)

lining to waterproof the bottom of the sanitary landfill.


217

The bottom of the domestic waste sanitary landfill should be waterproofed immediately

after removing the superficial layer of soil from the operational area and this work

consists basically of laying the high density polyethylene (HDPE) membrane on the

compacted clayey soil. Once this geo-membrane is installed, it is covered with a layer

of earth to protect it against perforation and cutting by materials contained in the

waste.

Once the waterproofing work is completed the network of leachate collection pipes

should be laid. The passing of the leachate collection pipes through the plastic membrane

is done by means of a special union already incorporated in the membrane that is

soldered to the body of the tube.

The soldering of the membrane sections should be done by a specialized team and it

is recommended that the supplier provides this service.

In some cases, such as smaller sanitary landfills or where soil conditions are relatively

favourable and underground bodies of water are deep, the bottom of the landfill can

be waterproofed with an at least 80cm thick layer of compacted clay with a

permeability coefficient of less than 10-6cm/s. The viability of this solution should

be verified by specific technical studies carried out by the project management and

its approval depends on compliance with the relevant environmental body’s regulations

and norms.

DRAINAGE WORKS

“Water does not enter a landfill plot from outside or come out from inside of it without

being controlled.”

This principle requires the installation of three drainage systems for liquids:

Peripheral interception drainage that stops rainwater entering the landfill and

contaminated water exiting it;

Landfill bottom drainage leading effluent and contaminated water to the treatment

unit;

Superficial drainage installed during the operational stage minimizes rainwater

infiltration and consequently reduces the flushing of contaminants, the quantity of

effluent and the anaerobic reaction in the mass of buried waste.

Access roads (permanent or temporary) have their own drainage systems that also

serve service roads.

Whenever possible rainwater drainage should be through ditches lined with cement

soil, grass, etc. to avoid the use of buried pipes. The collection of percolated

leachate should be done through pipes laid on the waterproofing layer at the bottom

218

Figure 121 - Leachate drainage system

PVC pipe

Pumpingunit Collection pit

See enlargement

Principal drainage pipe

LANDFILL

Pumping unit

Collection pit

Principaldrainage pipe

Bidim ®

LANDFILLPVC pipe

PVC pipe

To ETU

Percolated liquid minimum levelSumergible pump

Clay protection layerHDPE membrane

Secondary drainage pipe

Effluent treatmentunit (ETU)

PLOT 1 PLOT 1

PLOT 2 PLOT 2

1.5m

60m30m

L

Secondary drainage pipe

of the landfill in a zigzag pattern, with secondary pipes that conduct the collected

leachate into the main pipe. The liquid flows to a storage pit from where it is pumped

to a treatment plant, see figure 121.

These pipes should be bedded on gravel or crushed stone (blind drainage) and covered

by large grain, and then medium grain sand in order to avoid the silting of the pipes by

solids suspended in substantial quantity in the leachate. Geo-textile membranes can

be used instead of the layers of sand. This system is the most frequently used for a

sanitary landfill’s secondary drainage lines.

A more effective alternative is to install a Poly Vinyl Chloride (PVC) or HDPE perforated

tube in the gravel bed. The whole, formed by the pipe and the gravel, should be wrapped

in geo-textile membrane to avoid silting. This is used for the sanitary landfill’s principal

percolated liquid drainage lines.


219

Figure 122 - Types of underground leachate drainage pipe

The following figure shows cross sections of these two types of underground pipe.

INSTALLATION OF EFFLUENTTREATMENT SYSTEM

The determination of the best leachate treatment system and its dimensions for a particular

landfill requires a previous study of the characteristics of the actual effluent generated in

the sanitary landfill. This circumstance does not prevent, but on the contrary requires, the

inclusion in the sanitary landfill project of an initial treatment facility (for at least primary

treatment) and a final monitoring lagoon before discharge into the receptor body.

The effluent treatment process can be biological, physico-chemical, physical, thermal

or a mixture of these (combined processes).

A low cost process that can be used is the recirculation of the effluent through the mass

of buried waste, the decomposition of which tends to intensify with the addition of micro

organisms contained in the effluent. At the same time the mass of waste functions as a

filter, reducing the contaminating potential of the re-circulated effluent. Another advantage

is the reduced volume of effluent to be treated due to evaporation by sun and wind.

This stage of effluent treatment system works should therefore include at least the

installation of a leachate recirculation system, storage pit and primary treatment plant.

220

Figure 123 – Leachate treatment lagoon

CONSTRUCTIONS WORKS

Construction works include the foundations and superstructure of support buildings

and the treatment plant.

Before works commence it is very important to check the location of these buildings

again as this is the last opportunity to modify plans, adapting them to some condition

of the site that may have been overlooked during the formulation of the master plan.

As in all works of a certain size, adjustments often have to be made due to difficulties

that arise on site, for example modifications in the route of internal roads may be

necessary where they are incompatible with the location of support units.

Any modification or adjustment of the plan should ideally be made by the planning

company, or at least it should be consulted, because it holds all the information and

technical specifications covering the overall context of the work. It is recommended

that the planner is on site during construction work.

ELECTRO-MECHANICALINSTALLATIONS

The assembly of the weighbridge should meticulously follow the manufacturer’s

instructions and the weighing platform should be perfectly level. Once installed the

weighbridge should be officially calibrated in the presence of the supervision team.

It is obligatory that a weighbridge is mounted on pillars so that the weighing platform

does not settle and therefore remains level.


221

Figure 124 - Location of environmental monitoring wells

Figure 125 - Outline cross-section of a monitoring well

Protectingstructure Cover

Thread cap

PadlockInternal lining

(Ø 4” rigid PVC pipe)

Sanitaryprotection

Protection slabSanitary seal

Ø Hole 8”Ø Pipe 4”

Filling (impermeablematerial: clay,

excavated earth)

Cement seal

WT (Water Table)Pre-filter (washed

sand or quartz gravel) Perforated orgrooved pipe

Fixed cap(pressure or thread)

Impermeable layer

5.00

Flow of underground water Landfill

Operationalarea

Monitoring well

Watercourse

Surface water samplecollection points

DIGGING OF ENVIRONMENTALMONITORING WELLS

At least three monitoring wells should be dug, one upstream and two downstream

from the sanitary landfill operational area, incorporating the elements shown in figures

124 and 125.

Surface water should also be monitored at different points along any nearby body of

water upstream and downstream from the sanitary landfill area of influence.

222

COMPLEMENTARY WORKS

Finishing works on the landfill site, including landscaping and general cleaning work.

Depending on the location of the landfill, the acquisition of materials and machines

can present difficulties. Construction materials should be bought from traditional market

suppliers that are if possible located close to the site.

Arrangements should be made so that machines and vehicles necessary for particular

tasks arrive on the site in accordance with the work schedule.

13.3.5 Sanitary landfill operation

Once the installation work is finished and the operational authorization has been

obtained, the sanitary landfill can begin receiving loads of waste in accordance with

the pre-established operational plan.

The operational plan should be simple and cover all the routine activities carried out at

a sanitary landfill while at the same time making provisions for their safety.

The basic activities carried out at a sanitary landfill are listed below:

WASTE RECEPTION CHECKING

On entering the landfill site the collection vehicle goes directly to the weighbridge

where it is weighed and all the information relating to its load is registered. If there is

no weighbridge, the vehicle goes to the entry checkpoint where the responsible person

writes down data identifying the truck and its load, including an estimate of its weight

(or volume). The vehicle then goes to the operational area to unload the waste it is

carrying.

LANDFILL OPERATIONS

When the construction method for a landfill is being determined, three main factors

have to be taken into account:

! topography;

! soil type;

! water table depth.


223

Figure 126 – Trench method

Figure 127 – Ramp method

In general there are three possible methods of construction and the choice depends

on the concept behind the particular sanitary landfill project and, in the last analysis,

the site conditions. The construction methods are:

Trench or ditch method – this is the most appropriate technique for land that is flat

or has only a slight incline and where the water table is relatively deep.

Ramp method – this is appropriate where the landfill site is flat, dry and with a type of

soil suitable for use as waste covering material. A natural embankment against which

cells can lean inspires the name of this construction method.

Area method – this is the most appropriate technique for a completely flat site and

begins with a berm (artificial embankment) of clayey soil against which the first cells of

waste lean. Subsequently procedures are the same as for the ramp method.

224

BERM

1 Cellst

2 Cellnd

RUBBISH

Figure 128 – Area method

Solid waste disposal processes are almost identical in the three methods.

The basic rules of operation for a sanitary landfill are:

! the distribution and compaction of waste should be done if possible from the bottom

to the top to achieve better results;

! to obtain good compaction the waste should be distributed in not very thick layers

and a bulldozer should pass over the mass of waste of each layer three to six

times;

! the height of the cell should be between four and six metres to provide optimum

decomposition conditions for the buried waste;

! the usual incline of operational slopes is one metre of base for each metre of

height in an active cell and three metres of base for each metre of height in a

finished cell;

! the ideal thickness of the coverage soil layer is between 20cm and 30cm for the

daily covering of waste;

! the final layer of covering material should be at least 50cm thick;

! the cell should be as narrow as possible but wide enough to allow the simultaneous

unloading of a certain number of trucks depending on the sanitary landfill’s capacity

(or the demands of collection) so that queues do not form and collection is not

delayed.

The procedures to be followed for each cell in each of the operational plots of the

sanitary landfill, on each of the levels (superimposed layers) are:

! prepare the work face, including a truck manoeuvring area with primary surfacing

that is big enough for trucks to unload their waste and make the necessary turning

manoeuvres to return;

! with a provisional 20cm thick layer of soil cover the top of the cell, with an incline

of 2% towards the edges, and the internal slopes;

! cover the external slopes with the definitive 50cm thick layer of clay;


225

pH (un.)

Total Kjeldahl Nitrogen

Nitrate Nitrogen

Nitrite Nitrogen

Ammoniacal Nitrogen

COD

5.9 8.7

15.0 3,140.0

0.0 5.5

0.0 0.1

6.0 2,900.0

966.0 28,000.0

Table 24

Range of leachate composition variation

ParametersMinimum

Range of variation

Maximum

! some days before completing cell 1, prepare the work face for unloading waste

into cell 2 in the same way as for cell 1;

! as cell 1 is being filled the gas venting system should be progressively built into it;

! repeat the operations for filling each cell and preparing the next one until plot 1 is

entirely filled;

! repeat the same operations to fill plots 2, 3 and so on until the lower level is

completed;

! fill cell 1 of the upper level following the same operational sequence used on the

lower level;

! when burying the cells of the last level, make the final coverage of the completed

cells with a layer of 50cm thick compacted clay, with an incline of 2% towards the

edges;

! repeat the sequence of operations until all plots on all levels are completely filled.

EFFLUENT TREATMENT

The main characteristic of sanitary landfill effluent is its changing composition over

time, due to progressive exhaustion of the biodegradable organic matter. Consequently,

the high contaminating potential of “new leachate” gradually reduces over a period of

ten years to a point when it does not need treatment.

Table 24 shows the range of parameter variation for some sanitary landfill percolated

liquids in Brazil and is presented here as an example of the difficulties involved in a

definitive pre-establishment of the type of effluent that will be produced in a particular

sanitary landfill. These difficulties arise because the type of effluent produced depends

on the particular characteristics of the waste (determined by its component substances)

deposited in the landfill and on a series of specific factors that influence the

decomposition process in the mass of organic waste.

226

Source: Data compilation, COMLURB (Rio de Janeiro, Brazil), 1993.Note: all values are in mg/l, except where another unit is indicated.

Table 24 (cont.)

ParametersMinimum

Range of variation

Maximum

BOD5

Chlorides

Sulfates

Total Phosphorus

Copper

Lead

Iron

Manganese

Zinc

Cadmium

Total Chromo

Faecal Coliform (un.)

Total Coliform (un.)

480.0 19,800.0

50.0 11,000.0

0.0 1,800.0

3.7 14.3

0.0 1.2

0,0 2.3

0.2 6,000.0

0.1 26.0

0.1 35.6

0.0 0.2

0.0 3.9

49.0 4.9 x 107

230.0 1.7 x 108

The volume of percolated liquid produced by a sanitary landfill registers seasonal

variations depending on climatic conditions in the region and the local drainage system.

It is influenced by temperature, rainfall quantity, evapotranspiration, the nature of the

cell coverage material and in particular its permeability, the vegetation cover on the

sanitary landfill area, and many other factors.

A way of calculating the potential flow of effluent from a new sanitary landfill is by

direct correlation with percolate generation data obtained from measurements in similar

but already operating landfills located in regions with similar climatic conditions. However

distortions may occur.

Another procedure is the “Swiss method” that calculates the flow of sanitary landfill

percolated liquid by means of an equation involving the dimensions of the operational

area, the annual rainfall and a factor determined by characteristics of the land. Another

more complex procedure calculates the production of sanitary landfill percolated liquids

through the water balance.

Stabilization lagoons

One of the most frequently used forms of treatment involves lagoons into which

leachate effluent is discharged after passing through a grate or a mechanical sieve and


227

Figure 129 - Treatment in aerobic lagoons

Percolatedrainage

Equalizationtank

Grates

First aerobiclagoon

Overflowoutlet

Finishinglagoon Receptor

body

Second aerobiclagoon

Sanitarylandfill

remaining for at least 24 hours in an equalization tank to homogenize its composition

as much as possible. The following figure presents an outline of a typical leachate

treatment system employing aerobic lagoons.

It is recommended that a superficial aeration device is installed in the equalization tank

to improve the homogenization of the liquid mass and the aerobic condition of the

effluent to be treated.

In general aerobic stabilization lagoons have the following basic characteristics:

! form – truncated pyramidal;

! depth – 1.5 metres;

! retention time – 25 days minimum.

Entry to the lagoons should be through a two pipe system to improve the flow of

effluent in the lagoon avoiding dead zones and short cuts. The height of the effluent

overflow outlet should be adjustable to ensure that leachate remains inside the lagoons

for the minimum required time irrespective of the flow volume.

This series of lagoons ends with a smaller one where the effluent receives a finishing

treatment. This lagoon is also aerobic and has the same physical characteristics as the

previous ones but only retains the effluent for seven days.

Lagoon borders should be treated so that no vegetation grows in the air-effluent

intermediate zone, as such vegetation could harbour mosquitoes and other vectors.

In addition, sludge should be periodically removed so that the effectiveness of the

treatment is not impaired.

228

This removed sludge should be put to dry in a drying bed and then deposited in the

sanitary landfill, while the liquid can be directly discharged into the receptor body.

In determining the type of treatment to use the more correct procedure is a laboratory

study of the effluent’s characteristics. It is not advisable to use only documented data

to calculate the necessary dimensions of a treatment unit.

Effluent flow measurement should be carried out at a minimum of two points on the

treatment system:

! immediately after the storage pit or immediately before the equalization tank

! immediately before the point of discharge into the receptor body

Gross effluent and treated effluent should be periodically monitored.

Recirculation

Another commonly used treatment of sanitary landfill percolated effluent is its

recirculation through the mass of waste using sprinklers, tank trucks or infiltration

beds.

In this process the effluent gradually looses its toxicity (basically its organic content)

due to airing and the biological action of micro organisms present in the mass of waste.

In addition part of the re-circulated effluent evaporates and to encourage this sprinkler

nozzles should be adjusted to produce a fine spray, thus increasing the rate of

evaporation.

Evaporation is an important factor in leachate recirculation and it functions better in

regions with a negative water balance, that is, regions where the rate of evaporation is

higher than that of rainfall. It can also be used in other regions during dry seasons as

an auxiliary procedure complementary to the principal method being used.

Another important aspect to consider is that the leachate storage pit should have

enough capacity to store a sufficient amount of liquid for the recirculation pump not

to have to be used at very short intervals.

Ideally the pit should be designed to hold one complete day’s production of leachate

during the rainy season, thus making it possible for recirculation to take place only

once a day and preferably during the eight hour period that the operator is present at

the sanitary landfill.

The disadvantages of this process stem from its high electricity consumption together

with its dependence on a constant supply of electricity and the functioning of the

pump. If the electricity supply or the recirculation pump fail, gross effluent will inevitably

drain into some body of water producing environmental damage.


229

Figure 130 - Infiltration bed recirculation

Submergible pump Service roads

Nº 2 gravelbeds

Ditch for percolated liquid

Ditch for percolated liquid

Suction pit

Recirculation areaPerforated PVC

pipes Ø ½”Pumping pipePVC Ø 02”

Landfill

Landfill

Suctionpit overflow

Drainage valley

Ideally recirculation should serve as a complementary procedure to one of the

conventional effluent treatment processes, such as stabilization lagoons or an activated

sludge system.

The following figure shows a recirculation system using infiltration beds.

Activated sludge

Other processes that can be used in the treatment of sanitary landfill percolated liquids

are the activated sludge system and evaporation.

In the activated sludge system effluent passes through a preliminary treatment generally

in the form of a chamber with bars after which it is directed to a primary settling tank

where solids settle. It then goes to an aeration tank where aerators, usually on the

surface, inject air into the liquid mass allowing the aerobic bacteria to stabilize the

organic matter, which generates a secondary sludge that remains in suspension.

The effluent from the aeration tank passes to a secondary settling tank where the

previously generated sludge precipitates. A part of that sludge then returns to the

aeration tank while the settled sludge is put together with the sludge from the primary

settling tank and goes to a drying bed. The dried sludge is taken back to the landfill for

disposal.

From the secondary settling tank the liquid part goes to a finishing lagoon similar to

the one at the end of the aerobic lagoons process, from where it is discharged into

the receptor body.

230

Figure 131 - Activated sludge

Figure 132 - Leachate evaporator

Aerationtank

Primarysettling tank

Preliminarytreatment

Secondarysettling tank

Aerators

Finishinglagoon

Flowmeasurement

Receptorbody

T= 8

0ºC

to 9

0ºC

Biogasinlet

Thermallining

Humidityfilter

Sludgepump

Supporting base

Biogasinlet

Treated air outlet

Temperatureof departingair 750ºCto 900ºC

Chimney

Combustionair

Burner

Percolatedliquid inlet

Evaporator

Concentratedsludge

Sludge outlet

Average concentration30% solid

Evaporation

In the evaporation process effluent is sent to a metal tank, the evaporator, where it is

heated to a temperature of 80ºC to 90ºC causing part of the liquid to evaporate and

consequently the effluent to become more concentrated.

The hot vapour leaving the evaporator passes through a filter that retains humidity and

then goes to a final heating chamber from where it is discharged, dry, into the

atmosphere.

The sludge, now more dense with 30% of it being solid material, comes out through the

lower part of the evaporator and is disposed of in the landfill.

The great advantage of this process is its low operational cost as the fuel used to

evaporate the effluent is biogas from the sanitary landfill itself.


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Figure 133 - Installation of gas drainage wells

Whatever treatment option is selected, treated effluent should meet all discharge

standards established by the environmental control body.

RAINWATER DRAINAGE SYSTEM

The rainwater drainage system should be kept clean and free of obstructions, particularly

underground conduits.

As the sanitary landfill is constructed with solid waste, comprising mostly organic matter,

the decomposition process that gradually takes place in the mass provokes frequent

settlings of the surface.

It is important to constantly make adjustments to the system accommodating to these

movements in the mass of the landfill, at its edges, and on the slopes, in order to

promptly correct potentially damaging effects on the rainwater drainage devices.

GAS VENTING

The gas venting system comprises vertical wells surrounded by gravel or gross ground

stone, located at a distance of 50m to 60m from each other.

There are two methods for installing a gas drainage system: extending the pipe as the

landfill evolves (recommended) or excavating the completed cell to install the pipe. In

both cases the pipe should be high enough to serve as a guide for its further extension

when work begins on the next level up.

Once the well is installed, the ground around it should be covered over a radius of

approximately two metres with a 50cm thick layer of clay to avoid the dispersion of

gas into the atmosphere.

A burner should be installed in the mouth of the well. The gas venting system should

be constantly monitored so that burners are always alight.

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ENVIRONMENTALMONITORING

The monitoring of water in the area surrounding the sanitary landfill should begin before

the commencement of its operational phase with the collection and analysis of samples

from nearby bodies of water and the water table. The quality of these samples is

evaluated so that they can be compared with future samples.

The second phase of environmental monitoring commences when effluent generated

by the sanitary landfill begins to be stored for treatment and gases begin to be produced.

The frequency of sampling and the parameters that are analyzed must comply with

regulations established by the environmental control body.

Example of an environmental monitoring program:

! Monthly - physical, chemical and bacteriological analyzes of gross and treated effluent

in the treatment system, including tests for pH, BOD, COD, total and fixed sedimentary

residues and colimetry tests.

! Every three months - analysis of water from the monitoring wells and from water

body sampling sites both upstream and downstream from the sanitary landfill,

analyzing results for the same parameters in each case.

GEOTECHNICAL ANDTOPOGRAPHICAL MONITORING

At all times during the filling of sanitary landfill cells attention must be paid to

topographical alignment, up to and including the creation of the final covering surface

incline. Careful attention should also be paid to topographical aspects in determining

the incline of percolated liquid drains to ensure optimum drainage conditions after

collection.

In addition to these considerations, concrete frameworks should be installed in the

work faces for the purpose of monitoring the differential settling of the buried layers.

These frameworks should be read monthly, and the frequency of readings should be

increased when significant settling is observed. The reading of these frameworks will

also be useful to monitor the geotechnical stability of the sanitary landfill through the

measurement of horizontal displacement.

13.3.6 Equipment

Commonly used machines and vehicles for the operation of a sanitary landfill are:

! bulldozer - for the distribution, compacting and covering of waste;

! dump truck - for transporting coverage material and material for surfacing internal

access roads;


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! mechanical loader - to load trucks;

! mechanical digger - for digging and maintaining drainage ditches;

! tank truck – to supply water for reducing dust on internal roads and dampening

lighter waste (papers, plastics, etc.) to avoid it being scattered.

Factors that have to be taken into account when selecting machinery are: the availability

of financial resources, specialized labour for maintenance and spare parts for immediate

delivery. The sanitary landfill’s operational method is the principal factor that determines

the selection and dimensions of machinery needed for landfill operations.

As this equipment represents the most significant operational expenditure for a sanitary

landfill, a rigorous system controlling its use should be established not only in relation

to the number of hours that machines are operating for, and the wear and tear on

their components, but also in regard to their correct operation during daily tasks in

order to optimize their use and minimize unproductive procedures.

13.4 Controlled landfills

With everything that has been previously explained about sanitary landfills, from the

planning and installation phase to the final disposal of urban solid waste, the extensive

range of technical components involved in them can be appreciated as can the amount

of resources that it is necessary to allocate, not only for installation but also for their

ongoing operation in compliance with all the technical requirements and applicable

regulations.

In Latin American and Caribbean countries the limited availability of public resources

and the great demands made upon them create a situation in which it is very difficult to

establish sanitary landfills, to such a degree that only a few municipalities can install

them. In addition, even when the necessary financial resources are available for

installation there can be difficulties in obtaining sufficient resources and qualified labour

to operate a sanitary landfill in a way that meets its rigorous technical requirements.

Nevertheless, in spite of all these obstacles it is necessary to deal with the problem of

solid waste disposal as it has such serious consequences for sanitary and environmental

conditions in cities. In this context the alternative “controlled landfill” option arises, a

type of landfill that is often misunderstood or badly defined even by the technical

community itself. Such definitions tend to focus on specific aspects of particular

projects rather than providing a wider conceptual description.

The most appropriate definition of a controlled landfill is:

“A controlled landfill is a modified version of a sanitary landfill where the rigorous

technical requirements applicable to the latter are more flexible in order to facilitate

urban solid waste final disposal on the ground, with the waste duly isolated and covered,

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Figure 134 - Cross section of a controlled landfill

Upper waterproofing

Lower waterproofing

Controlled landfill

Maximumwater level

h>3.0m

Water tableFlow ofunderground water

Impermeable soil

complying with minimum sanitary control requirements through the selection of a site,

the natural characteristics of which minimize the risk of negative environmental impacts.”

The key to a successful controlled landfill project is therefore the choice of the land

where it will be installed, the principal characteristics of which should be: soil that is

not very permeable (clayey) and a deep water table (at least 3 metres below the level

of the natural land).

Where the soil type is not appropriate the controlled landfill project should make

provision for the installation of an at least 50cm thick waterproofing layer of clayey

soil brought from the nearest deposit.

The cells of a controlled landfill are also built with compacted layers of waste but

without necessarily using specialized machines (bulldozers, self-propelled waste

compactors), that is, waste can be manoeuvred using lighter equipment or manual tools,

though it must be routinely covered with earth.

It is common for controlled landfills to be used in small cities that collect up to 50 tons

of solid waste per day and where municipalities are not in an economic condition to

maintain, for example, a bulldozer exclusively and permanently allocated to final waste

disposal, or to implement, operate and maintain some of the systems required by the

norms that regulate sanitary landfills.

Of these systems it is the absence of effluent treatment that causes such municipalities

most problems. Consequently special care should be taken with the rainwater drainage

system of controlled landfills, as the more effective that system is the less effluent

will be produced in the landfill. In this respect it is also important that the waste coverage

layers are of clayey earth and particular attention should be paid to the top covering

when the landfill reaches its maximum height.

There is no exact definition of a “controlled landfill”, as they vary from very simple

installations to ones that are similar to sanitary landfills. A controlled landfill offers

municipalities with limited investment and budgetary capacity a relatively immediate

opportunity to operate a low cost urban solid waste disposal system that eliminates

the environmental and social aggression of refuse dumps, and in doing so demonstrates

the principle “the ideal can be the enemy of the good”.


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Figure 135 - Manual compaction of waste in a cell

One of the requirements for a sanitary landfill is the permanent presence of specialized

machines for the manoeuvring, compaction and covering of waste. This is not a realistic

possibility for most small-sized municipalities in Latin America and the Caribbean with

their budgetary limitations and the significant under use of equipment that this would

imply due to the relatively small amount of waste to be disposed of, as well as the

drain on equipment resources needed for other municipal services.

For such municipalities a controlled landfill allows for alternative solutions such as the

periodic and programmed use of machines from other municipal sectors - for example

those used for road maintenance - in the preparation of the weekly work face.

A mechanical digger for example could excavate trenches for future waste cells where

the land type permits the employment of this method of solid waste landfill construction.

In such a case resultant material would be stored in a nearby place for later use in the

covering operation. A practical alternative for small-sized municipalities is to use easily

obtainable manual tools for landfill operations. In this case additional compaction can

be achieved by collection vehicles being driven over filled areas as the cell advances.

When it is not possible to guarantee even the infrequent programmed availability of

machines to do the heavier work involved in landfill routines (such as excavating earth),

the selection of the site becomes fundamentally important for an effective functioning

of the controlled landfill. The ideal in such a case is a small dry natural hollow.

Manoeuvring and coverage work is done manually as described below.

The waste can be manoeuvred and the top surface and lateral sloped (1:1) surfaces

can be levelled using hoes, mallets, rakes, pitchforks and forks.

The covering of waste should be done at the end of each working day.

Waste compacting can be done with mallets.

An entirely manual operation is recommendable only for a daily waste volume of up to

40m³ or approximately 10 tons.

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Where a landfill is manually operated it is indispensable that workers engaged in the

manoeuvring and covering of waste have, in addition to the appropriate tools, clothing,

shoes and gloves that guarantee their protection and safety. On rainy days they should

wear plastic waterproofs.

13.5 Environmental recuperation of refuse dumps

As has been explained, a refuse dump is an inappropriate form of urban solid waste

disposal as it produces a series of negative environmental impacts and poses sanitary

risks for the population.

Areas degraded by refuse dumps should therefore be recuperated by containing such

impacts and re-establishing healthy conditions there.

Theoretically the correct way to recuperate land degraded by a refuse dump is to

collect all the waste inappropriately disposed of there and transfer it to a sanitary

landfill, subsequently recuperating the excavated area by filling it with natural soil from

the region. In practice however this procedure is not usually economically viable and in

most cases it is anyway impossible to implement due to the physical characteristics of

the dump site.

It should be noted that the strategic context of a refuse dump environmental

recuperation exercise can be:

! that the area will be recuperated after it is closed for the dumping of waste, or

! that the area will be recuperated in such a way that it will be able to continue receiving

waste but on a sound sanitary and environmental basis.

An analysis of these alternatives is fundamental to appropriate planning for future

solid waste final disposal. It is always recommended, especially in cities with restricted

financial resources, that investment in the environmental recuperation of a dump is

combined with the creation of disposal service and environmental protection

infrastructure in the same place, thus allowing for the continued disposal of waste

there but in sanitary conditions.

In this way the municipality can avoid generating negative impacts on a virgin site before

exhausting the waste disposal capacity (useful life) of the area previously used as a

refuse dump. Another aspect to consider is the availability of resources. Often a

municipality does not have access to sufficient finance for carrying out two works,

that is, the recuperation of the degraded refuse dump area and the installation of a

new final disposal system on another site, so it will naturally opt for undertaking the

latter and leave aside remedying the environmental liability incurred by the refuse dump.

Therefore whenever possible the refuse dump site or neighbouring land should be

used to install a new final disposal system, in order to optimize the use of resources

and maximize sanitary, environmental, technical-operational and economic results.


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When a refuse dump is permanently closed, thus ending any type of waste disposal

there, and site recuperation is undertaken, the basic procedures are:

a) if there is no reliable cadastral data, previous urban cleaning personnel should be

consulted to determine as precisely as possible the extent of the area affected by

waste and the principal physical characteristics of the natural land;

b) delimit the affected area in situ;

c) carry out probes to measure the thickness of the layer of waste throughout the

degraded area;

d) remove the waste from the parts of the site where the layer of waste is thinner (in

general less than one metre) and deposit it on the part of the refuse dump where

the layer of waste is thickest;

e) form lateral slopes with an appropriate incline, in general 1:3 (V:H);

f) give the top surface an incline as indicated in the section on drainage;

g) after they have been levelled, cover the exposed waste surfaces with an at least

50cm thick layer of good quality clay, including the lateral slopes;

h) recuperate the excavated area by filling it with natural soil from the region;

i) install rainwater and leachate drainage devices appropriate for the particular project;

j) dig one or more storage pits for effluent collected by the leachate drainage devices;

k) construct vertical wells for gas venting;

l) spread a layer of top soil over the layer of clay on the top surface and slopes;

m) sow grass and native plant species with short roots;

n) use three of the previously made probe holes to install water table monitoring

wells: one on the upstream side of the area of the recuperated dump and two on

the downstream side.

The recuperation of a refuse dump does not finish with the implementation of these

procedures. Leachate that accumulates in the storage pits should be periodically re-

circulated in the mass of waste, through sprinklers (similar to those used for grass

watering) or infiltration beds; gas vents should be periodically checked so that those

extinguished by wind or rain can be relit; and the quality of underground water should

be checked through the monitoring wells, as should the surface water in nearby bodies

of water.

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As has been previously explained, due to the difficulty of finding new sites appropriate

for sanitary landfills, whenever possible a recuperated dump site should continue to

be used, but as a landfill. In this case, the sequence of procedures listed in the previous

paragraph is modified after point “g” in the following way:

! prepare the excavated area to receive more solid waste, waterproofing it with good

quality clay and installing underground pipes to collect leachate;

! install the necessary rainwater drainage channels to stop rain water run off reaching

future work faces;

! excavate one or more storage pits for effluent generated in new cells;

! as the landfill evolves build vertical wells for gas venting;

! establish procedures for distribution, compaction and covering as if it were a sanitary

landfill;

! install a leachate recirculation system and (depending on the climatic conditions of

the zone) an effluent treatment system with stabilization lagoons;

! dig water table monitoring wells, one upstream and two downstream from the future

operational area.

13.6 The situation of segregators

In the present situation of Latin American and Caribbean countries there are not enough

employment opportunities in the formal work market to allow universal entrance into

it by a growing population, which together with low work training levels leads people

to seek any activity that at least provides a means of survival for themselves and their

families.

Even though recyclable waste segregation in refuse dumps and streets is an unhealthy

activity, it has become an “alternative job” as a result of the now endemic large-scale

social crisis.

Segregators tend to circulate freely in the operational area of a refuse dump, together

with collection trucks and scrap dealers, and such activity hinders distribution,

compaction and covering operations, in addition to creating a serious risk of accidents

involving the working machines and vehicles.

Even more serious is the presence of children at dumps, either due to a lack of

alternative options for parents who do not have anybody to take care of them while

they are engaged in segregation work, or because the children themselves are

segregating materials in order to increase family income.

Refuse dump recuperation projects are therefore not limited to engineering issues

but also have to solve a complex social problem that cannot and should not be the

sole responsibility of the body providing urban cleaning services, but rather requires

articulated action involving various governmental sectors.


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Figure 136 – Recycling plant operated by a segregator cooperative

Some of the initiatives that should be implemented to gradually change this situation

are the development of alternative income and employment programs (such as

segregator cooperatives, for example), the provision of technical training for

segregators so that they can engage in other activities in the formal labour market,

cooperation with non-governmental institutions and private companies, programs that

provide children with integral fulltime places in schools or sports and recreational

centres and a compensatory system for parents whose children cease to engage in

segregation work.

13.7 Special domestic waste disposal

13.7.1 Construction rubble disposal

As has been explained in the chapter on solid waste treatment, the ideal destiny for

construction rubble is recycling.

However when a municipality does not have this option, it is disposed of at the bottom

of a landfill.

Disposing of construction rubble in a sanitary landfill is not economical as it is inert

waste that is being deposited in a specialized system surrounded by technical resources

designed to protect the environment, when it could be disposed of in more simple

landfills at a lower cost.

Depositing this type of waste in a sanitary landfill is also not economical from an

environmental perspective as the useful life of the landfill will be diminished by waste

that, with effective management, could be used for the recuperation of excavations

resulting from the extraction of materials used in the construction industry.

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The only appropriate types of rubble disposal in a sanitary landfill are:

! its use as base material for internal roads and unloading areas;

! its use for the temporary covering of urban waste when there is a scarcity of the

usual covering material in the zone.

13.7.2 Disposal of batteries

As used batteries constitute hazardous waste, particularly due to the presence of

heavy metals in their composition, their final disposal should be managed with the

same criteria as are applied to industrial waste that carries the same type of risk.

Before organizing a system for battery separation at source, with a view to recycling

or another form of treatment and final disposal, the body responsible for urban cleaning

should ensure the participation of producers, dealers and other players in this economic

sector, who should be responsible for financing such a process.

This waste should be regarded as waste from the industrial process of its producers,

who should therefore be responsible for its collection, treatment and final disposal.

Corresponding regulations should be brought into force in support of this type of

model to avoid the risk that the municipality will be left with responsibility for costs

associated with production process waste from private sector enterprises.

Two initiatives are presented below as examples of measures that the private sector

can adopt for the collection and final disposal of batteries.

! develop a project together with associations of authorized technical service

providers for the installation of battery collection containers on their premises.

Batteries collected in this way would be removed once a month and taken to a

treatment or recycling site.

! establish an agreement with mobile phone producers under which they set up a

discarded battery collection program that includes the provision of a telephonic

information centre providing the location of places where there are special containers

for used batteries.

13.7.3 Disposal of fluorescent tubes

Often small pieces of broken tubes are accidentally discarded together with common

waste in sanitary landfills.

However, as there is mercury in them the appropriate final disposal of such waste,

especially in large amounts, is in a landfill designed specifically for industrial waste with

this risk classification. In this case too the “polluter pays” principle applies.


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13.7.4 Disposal of tyres

When it is not possible to recycle used tyres or use them in cement industry furnaces,

for example, they can be disposed of in sanitary landfills after being ground so that

they do not cause structural problems in the landfill.

The body responsible for urban cleaning should not have to take on the problematic

final disposal of used tyres, which should be the responsibility of producers and

distributors as it is their economic activity that generates this waste.

In support of this current perspective on the problem national legislation is needed to

facilitate a progressive reduction in the quantity of such waste through a policy that

fosters recycling by the industry and suppliers.

Finally it is necessary to pay attention to the import of used but still usable tyres as

together with these goods the companies of exporter countries are also exporting

the problem of disposal when they are of no further use.

13.8 Disposal of waste from special sources

13.8.1 Industrial waste disposal

Soil bio-regeneration (land farming), industrial landfills, waste barrages and other forms

of disposal are commonly used for industrial waste.

SOIL BIO-REGENERATION

Soil bio-regeneration (land farming) is a biological treatment through which the organic

part of waste is decomposed by the micro organisms that live in the upper layer of

soil. This treatment is very much used for the final decomposition of oil by-products

and organic compounds.

The treatment consists of mixing and homogenizing waste with the upper layer of

soil (to a ploughing depth of 15cm to 20cm). Once the micro organisms complete

the degradation work, a new layer of waste can be treated in the same soil, repeating

the same steps, and so on. Although the same land can be used repeatedly the

disadvantage of this method is its need for large areas of land as the layers are not

thick.

The following figure shows an outline cross section of a bio-regeneration area.

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Figure 137 - Soil bio-regeneration outline

Figure 138 - Flow of water in a landfill

Periodic application andmixing of waste and soil

Containment of rainwater thatfalls on the treatment area

Diversion ofrainwater that

falls outside thetreatment area

Aerobic decomposition, absorptionand adsorption in the upper layer

Watercourse

200 m

Evaporation

Infiltration

Rain

Evaporation

Superficial drainage

Leaching Wastelandfill

Percolation

Impermeable soil

Non-saturatedzone

Flow ofunderground water Wastewater

Maximumwater level

Leaching

INDUSTRIAL LANDFILLS

Industrial landfills are classified according to the hazard presented by the waste to be

deposited there. In Brazil, for example, landfills for Class I waste can receive hazardous

industrial waste; those for Class II, non-inert waste; and those for Class III, only inert

waste.

In any type of industrial waste landfill a rainwater drainage system and bottom

waterproofing are essential to avoid soil and water table contamination from rainwater

that has percolated through the waste, as demonstrated in the following figure.

In order to reduce the amount of effluent to be treated, the first step is to avoid, by

means of barriers and drainage ditches, the incursion of rainwater falling outside the

limits of the landfill that would otherwise increase the volume of effluent percolating

inside the landfill.


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Figure 139 - Industrial landfill for Class I waste - typical cross-section

Final coveragelayer

Rainwater drainage

t = 0.60 to 1.00mPlastic

membraneVegetationcoverage

Pumping unit

To the effluenttreatment unit

Storage pitWasteWaste Blind drainage

I = min 0.5%

Waste

Waste

I = 2%

Drainagelayer

h = 4 to 6m t = 25cm

t = 20 to 30cm Intermediatecoverage

(soil – t = 25cm)

Plastic membrane(double layer)

t =1.0 to 2.5mm

Physicalprotection layer

t = 30cm

Leakage detectionlayer (t = 25cm)

Maximumwater level

h > 3m PVCtube

The second step is waterproofing the bottom of the landfill with a plastic membrane in

order to stop leachate contaminating the soil and the water table.

The main disadvantage of an industrial landfill as a means of final waste disposal is that

it requires a large area of land in order to be economically and operationally viable and

it should be taken into account that the waste continues to be potentially dangerous

until it can naturally incorporate itself in the environment. In this context the best

course of action is to concentrate efforts on earlier stages, that is, on the reduction

of waste production and its treatment so that only unusable refuse is deposited in

industrial landfills.

An industrial landfill with a capacity of 15,000 tons requires an initial investment of

approximately two million dollars and involves operational costs of 50 to 150 dollars

per ton. The operational cost varies according to the waste’s degree of toxicity.

When operating an industrial landfill special precautions have to be taken to control

the type of waste unloaded there as only chemically compatible wastes can be disposed

of in any given landfill, that is, wastes that do not react in contact with each other or

with infiltrated rainwater.

The most common phenomena produced by the mixture of incompatible wastes are:

heat generation, fire or explosion, production of smoke and gases that are toxic and

inflammable, dissolution of toxic substances and violent polymerization. Consequently,

before waste is unloaded at the landfill the list of compatible wastes published by

environmental control bodies must be consulted.

Industrial landfill for Class I waste

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Figure 140 - Industrial landfill for Class II and Class III waste – typical cross-section

Final coveragelayer

Rainwater drainage

t = 0.60 to 1.00m

Vegetationcoverage

Pumping unit

To the effluenttreatment unit

Storage pitWasteWaste Blind drainage

I = min 0.5%

Waste

Waste

I = 2%

Drainagelayer

h = 4 to 6m t = 25cm

t = 20 to 30cm

Plastic membranet = 0.8 to 1.5mm

Physicalprotection layer

t = 30cm

Maximumwater level

h > 1.5m PVCtube

Industrial landfills for Class I waste require more rigorous waterproofing than those

for Class II and III. A minimum water table depth of three metres is required and the

following layers are compulsory:

! double layer of bottom waterproofing: PEAD membrane and clay protection layer (k

< 10 - 7cm/s);

! leakage detection layer between the bottom waterproofing layers;

! top waterproofing layer;

! drainage layer on top of the top waterproofing layer (t = 25cm).

Industrial landfill for Class II and Class III waste

Industrial landfills for Class II and Class III waste are similar to domestic waste sanitary

landfills but do not usually have a gas venting system.

Beginning at least 1.5m above the highest level of the water table and going from

bottom to top this type of landfill usually consists of the following layers:

! bottom waterproofing with PEAD membrane;

! physical protection for the plastic membrane;

! percolates drainage system;

! layers of waste (from 4.0m to 6.0m thick) with 25cm thick layers of soil between

them;

! although it is not obligatory, a top waterproofing layer of plastic membrane or good

quality clay (k = 10 - 6cm/s; thickness > 50cm) is recommended;

! 25cm thick sand drainage (necessary only where there is top waterproofing);


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! organic soil (thickness > 60cm);

! vegetation coverage with short root plant species.

The percolated liquid, collected through a drainage system similar to the one in the

previous figure, should be led to a treatment unit. The type of treatment depends on

the characteristics of the waste deposited in the landfill but usually a complete physico-

chemical process is applied, followed by a conventional biological process (stabilization

lagoons or activated sludge).

WASTE BARRAGES

Waste barrages are used for the disposal of liquid waste as well as sludgy waste that

has a humidity content of more than 80%. These landfills are not deep and cover an

extended area. They have a filtration and drainage system at the bottom (flute) to

collect and treat the liquid part while containing the solid matter inside the barrage.

Such barrage systems use a double layer of waterproofing only on the bottom. A top

waterproofing layer is not required as the surface serves to evaporate off part of the

liquid content.

After the closure of the landfill, when the top layer of waste has solidified, the surface

is waterproofed with a layer of clay to reduce rainwater infiltration and thus the need

for ongoing treatment of percolated liquids.

OTHER FORMS OF DISPOSAL

Highly hazardous waste can be disposed of in underground saline or calcareous caves,

or can be injected into exhausted oil wells.

13.8.2 Radioactive waste disposal

There are three final disposal processes for nuclear waste, all very expensive and

sophisticated:

! construction of special shelters with double walls of high resistance concrete,

preferably underground;

! encapsulation in an impermeable concrete covering followed by dumping in the

deep ocean (this process is very much criticized by environmentalists and in some

countries is prohibited);

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! disposal in saline underground caves that are sealed so as not to contaminate the

biosphere.

13.8.3 Port and airport waste disposal

In some countries it is required by law that port and airport waste is disposed of by

incineration. However, in many of these countries only some ports and airports comply

with such environmental legislation while in the others no special attention is paid to

waste disposal.

In recent years the sanitary vigilance authorities of several countries have begun to

implement measures that increase controls in ports and airports out of a concern for

the potential economic impact of diseases such as foot-and-mouth or mad-cow disease

being “imported” from other countries or regions.

Port and airport waste not at risk of being contaminated by contact with waste generated

in boats or planes arriving from areas with endemic diseases can be disposed of in

sanitary landfills. It is therefore essential that an effective and safe solid waste storage,

handling and internal transport system is implemented in order to avoid contact between

common waste and waste that is contaminated or represents a potential sanitary risk.

13.8.4 Medical waste disposal

The only final disposal process for this type of waste in the ground is the septic

trench, a method that is very much questioned by most professionals but, due to its

low investment and operational costs, is a viable option for cities with budgetary

limitations.

Conceptually a septic trench is in reality a Class II industrial landfill, as described in

13.8.1, which involves the daily covering of waste and obligatory waterproofing but no

leachate collection.

There are two types of septic trench: individual ones such as may be used by large

hospitals and ones that are annexed to a municipal sanitary landfill.

In the first type, trenches should be excavated with dimensions appropriate for receiving

waste generated over a pre-determined period (a month, six months or a year). The

bottom and sides of the excavated trench are then waterproofed and waste begins to

be deposited there, the surfaces of which should be covered daily.

Top waterproofing should begin as soon as the volume of waste reaches its final

height and should progress at the same rate as the filling of the trench.

When the septic trench is annexed to a municipal landfill, a distinct plot should be

separated for medical waste disposal. This plot should be fenced and isolated from

the rest of the landfill.


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Figure 141 - Septic trench installed in a sanitary landfill

Finalcoverage

Drainagelayer

Plasticmembrane

Fence

Lateral slopescoverage

Topcoverage

3m to 4m

Plasticmembrane

Waste

Waste

Waste

The procedures for waste disposal and waterproof layer installation are similar to

those previously described.

13.9 Sanitary landfills and carbon credits:Opportunities to help resolve environmental problems

The environmental damage resulting from refuse dumps and irregular dumping always

causes significant problems for municipal administrations. The unpleasant appearance

and the bad odour that they emit discredit city administrations where waste is not

appropriately disposed of. From an environmental perspective dumps are a real calamity

as they contaminate the soil, the atmosphere, surface and underground water and

represent a potential source of epidemics and fires as well as being susceptible to

disintegration.

Many mayors have been held directly accountable by environmental bodies, auditing

tribunals and public prosecutors for poor urban cleaning management, especially in

relation to the final disposal of waste.

Attempting to resolve urban solid waste final disposal problems through the installation

of recycling or incineration plants is often not feasible as, in spite of spectacular

promotional offers by equipment manufacturers, they require significant financial

investment and their operation involves a high level of complexity, both of which are

beyond the capacity of municipalities that lack financial resources and specialized

personnel.

The simplest and cheapest option for solving the problem of refuse dumps is

undoubtedly the installation of sanitary landfills, provided they are well built and correctly

248

operated. Sanitary landfills do not contaminate or emit unpleasant odours and after

their final closure they can be used for the construction of sports complexes or public

parks.

Refuse dumps can be eliminated either by transforming them into sanitary landfills or

by eradicating them altogether in an environmentally sound way, in which case they

should be replaced by a sanitary landfill elsewhere that will then receive the city’s

domestic waste. However such initiatives involve investment and operational costs

that in general are beyond municipalities’ financial means.

As a result of this situation the problem of solid waste disposal in Latin America is far

from being solved, as is revealed by PAHO reports on basic sanitary services (see chapter

1), according to which the percentage of cities that still have refuse dumps is very high.

One potentially positive economic factor being studied with increasing attention as a

solution to this problem is the exploitation of biogas naturally produced during organic

waste anaerobic decomposition processes, approximately 50% of which is methane.

This combustible gas can be used to fuel boilers, furnaces and vehicle internal

combustion engines or to generate electricity, with the additional advantage that its

producers will receive Certified Emission Reductions (CERs), as established in the Kyoto

Protocol the objective of which is to reduce the proportion of gases that provoke the

greenhouse effect in the earth’s atmosphere. The naturally occurring “greenhouse

effect” is a phenomenon of the Earth’s particular type of atmosphere that ensures

climatic conditions favourable for life as we know it.

This new opportunity is beginning to receive support from the World Bank and other

international development bodies, which are offering resources and information for

the installation of sanitary landfills with systems that recover and exploit “waste biogas”.

In this chapter we will try to clarify the question of carbon credits as the recovery and

use of biogas for fuel has already been dealt with in many technical publications.

13.9.1 Greenhouse effect: causes and consequences

This phenomenon is similar to the one produced by the glass panels of a greenhouse

that retain heat produced by the sun. As with the glass panels of a greenhouse, the

presence of certain gases in the atmosphere, principally water vapour, carbonic gas

and methane, impedes the release into space of heat generated by the incidence of

the sun’s rays on the Earth’s surface, which is then reflected outwards.

If this phenomenon did not exist, our planet would be as cold and sterile as Mars, for

example, while if it existed to a greater degree the Earth would be similar to Venus,

sterile and with an extremely high ambient temperature.

Over recent decades the concentration of these gases in the atmosphere has

increased, principally due to the intensive use of fossil fuels such as coal and oil in

domestic and industrial activities and in transport. Consequently, the average


249

6 . Available on the Convention on Climate Change website http://unfccc.int/2860.php

temperature on Earth is increasing, thus endangering the delicate balance that makes

our environment liveable.

A dramatic example of what a change in the Earth’s climate can imply is the extinction

of the dinosaurs that once lived all over the planet and, according to the most accepted

theory, disappeared when a layer of dust was raised by the impact of a meteorite on

the surface of the Earth provoking a drastic fall in global temperatures.

Out of a concern to stop, or at least reduce, the acceleration of this process the UN

called a summit, Rio 92, which established the “Framework Convention on Climate

Change” that finally became the Kyoto Protocol 6 signed in 1997 in the Japanese city of

that name.

The Kyoto Protocol established that between 2008 and 2012 countries listed in its

Annex 1 (developed countries) should reduce their emission of green-house gases

(GHG) to a level approximately 7 % below that of 1995.

Following its ratification by Russia in November 2004, the Kyoto Protocol came into

force on 16th February 2005, the moment at which the timeframe for commitments

taken on in that international agreement became applicable.

The Protocol defined a baseline criterion separating the group of surplus emission

producing countries (credit buyers) and the group of sub-baseline producing

countries (credit sellers). Consequently commitments were established that defined

greenhouse gas emission reduction goals for developed countries listed in Annex

1 of the Protocol and a program of reduction quota commercialization. Countries

not included in Annex 1 of the Protocol, such as Latin American and Caribbean

countries, are not obliged by the Protocol to reduce emissions but rather can

transfer to Annex 1 countries credits corresponding to emission reductions

produced by projects implemented for that purpose that qualify as what are called

CDM (Clean Development Mechanism) projects.

13.9.2 The “logic” of carbon credits

The interest in buying Certified Emission Reduction credits is due to differences

between countries in the cost of emission reduction through processes applied to

installations. In developed countries these costs can reach to values higher than US$

500.00 per ton of carbon while in countries not included in Annex 1 of the Protocol

they vary from US$ 1.00 to US$ 30.00 per ton of CO2.

As a result of these cost differences the Emissions Reduction Market was created

where the current value of a ton of CO2 or equivalent that is not emitted, or is captured,

is approximately US$ 10.00.

Global carbon markets have therefore begun to form and several international funds

have been created to support the development of projects that reduce anthropogenic

250

carbon emissions. Each ton of CO2 that a developing country does not emit or captures

(that is, transforms for example into vegetable matter, a process called fixation in

plants) can be traded on the global market in the form of the above mentioned CER

credits.

In relation to the greenhouse effect it should be noted that each ton of methane is

equivalent to 21 tons of CO2. In consequence CERs are generated to the degree that

the combustion of methane takes place and the emission of CO2 equivalent is therefore

diminished.

For CERs to be issued, the planning, implementation and operation of a project should

be certified and audited by independent bodies authorized by the UN, taking into

account:

! whether the project is entered into voluntarily, that is, it is not required by law;

! whether there are real measurable long term benefits;

! whether emission reductions are additional to those that would take place if the

project was not implemented (baseline).

The application of CDM to sanitary landfills is very effective for emission reduction,

requires low investment, is aligned with public policies for the improvement of sanitary

and environmental conditions and results in a better quality of life for the urban

population by contributing to the transformation of refuse dumps into sanitary landfills.

To take advantage of this new economic opportunity, Latin American cities are beginning

to invest in urban waste treatments that reduce methane emissions and generate income

through CERs linked to sanitary landfill projects implemented in accordance with CDM.

In Argentina for example, the concession for the collection and treatment of methane

produced by the large sanitary landfill at Villa Dominico, Buenos Aires, has been put to

tender with the support and assistance of the World Bank. This is the first Argentinean

project that has been presented to the Kyoto Protocol Executive Council as a CDM.

The first CDM project approved by the Executive Council is in Brazil: an electricity

generating station fuelled by methane from landfill biogas in Nova Iguaçu (Rio de Janeiro).

The project is expected to capture the equivalent of 2.5 million tons of carbonic gas

(US$ 4.5 per ton) and its first client is the government of the Netherlands.

Another Brazilian project for implementation in the Salvador Centre Metropolitan

sanitary landfill (Bahia), already approved by the Brazilian government through the Inter-


251

ministerial Climate Commission, headed by the Science and Technology Ministry, is at

present awaiting the evaluation of the Kyoto Protocol Executive Council.

The first pilot project in Latin America was implemented in Uruguay at Las Rosas sanitary

landfill, Maldonando province, with the objective of capturing 18,962 tons of methane

over the course of 15 years.

It is therefore clear that the carbon credit market is rapidly expanding and adapting to

the CDM principles established by the Kyoto Protocol.

13.9.3 Circumstances in which biogas froma sanitary landfill can be utilized

For an effective implementation of a biogas recovery and utilization project, with its

consequent reduction of methane emission into the atmosphere, there are requirements

that have to be met. Here we present some of the essential conditions that the various

sectors involved in the operation of an urban cleaning system should fulfil in order to

achieve the established objective.

Institutional

The mayor and secretaries of departments related to municipal solid waste management

and the environment should clearly and unequivocally demonstrate their intention to

implement a permanent program of domestic waste collection and final disposal that

covers the entire urban population (universal coverage) in order to ensure healthy

conditions for everybody and the protection of the local environment.

To achieve these objectives there must be a separate management unit within the

municipal administration with sufficient training to carry out these functions, as well as

a specific annual budget allocation to municipal solid waste management large enough

to cover the system’s investment and operational costs. There should also be a national

policy for solid waste management establishing minimum service provision standards

and requiring the implementation of final waste disposal systems that are both sanitarily

and environmentally sound.

Finally, an organizational agreement should be established between the different

institutions involved in the project such as the municipality; the company operating

the sanitary landfill where that service is subcontracted; the electricity distribution

company or gas consumer company where there is energy or gas generation using

biogas; and national, provincial or municipal environmental conservation bodies.

252

Physical and operational

The existence of a sanitary landfill principally dealing with the disposal of domestic

waste with a high organic matter content that has already received a minimum quantity

of 15,000 tons of waste (corresponding to 25,200 cubic metres, considering a density

of 0.7t/m³, which occupies a volume that can be represented, to give an idea, by a

10m high prism with sides of 60m); the layer of waste is at least 10 metres deep; the

surface of the landfill and its slopes are covered with clay except for the work face

where trucks unload; and there is a regular reception of at least 50 tons of domestic

waste per day.

If the site is not operated in a sanitary way, that is, the waste is not covered with clay

and there is no leachate and biogas collection, the possibility of recuperating the land

at the same time as sanitary or controlled operations begin on it should be examined.

Disposal operations should preferably continue on the site of the old refuse dump,

provided that the ownership, urban zoning and minimum environmental conditions are

appropriate, in order to avoid the difficulties involved in the implementation of a new

landfill in an urban area even when it will be operated on a sound basis.

Social

A public awareness raising program should be instigated focusing on the issue of urban

cleaning with a view to informing all citizens about sanitary problems in their region,

the resources needed to solve them and the responsibilities that each party has in the

process.

13.9.4 Requirements for the implementation of GHGemission reduction projects in solid waste landfills

The implementation of emission reduction programs for methane produced in urban

waste landfills should comply with CDM requirements, so that they can be analyzed

and given different degrees of priority by the Interministerial Commission on Global

Climate Change, with a view to the possible allocation of public resources or investment

by the private sector at a national or international level.

In addition guarantees are required not only for an effective collection of the biogas

and the transformation of its methane into carbon dioxide (CO2) but also for the long

term continuity of the process as biogas continues to be produced during a period of

more than 15 years after the closure of a landfill as a waste disposal site.

Consequently the formulation of a table of conditioning factors is recommended that

can be filled in according to the specific characteristics of each project and subsequently

analyzed to determine if a given project can receive preliminary approval from the

national body responsible for the environment and later, where relevant, by the national

body responsible for climate change issues.


253

The following is a list of project related characteristics that will facilitate the analysis

of a given project prior to a decision on whether or not basic CDM requirements are

met:

! an urban population of more than 30,000 inhabitants;

! the existence of a body responsible for urban cleaning in the municipality;

! a qualified technical team within the responsible body;

! a waste collection system coverage of at least 80% of the population;

! a daily waste collection delivered to the site of at least 50 tons;

! a landfill operation that is ongoing and functions in a regulated way: a sufficiency of

machines, a landfill growth plan that is followed, the compaction of waste and its

regular coverage with a layer of clay, more than 10 metre thick layers of waste, a

collection and either treatment or recirculation of leachate;

! a sub-contraction of the landfill operation;

! a municipal budgetary allocation specifically for urban cleaning services that is big

enough to maintain the quality of those services at an appropriate level;

! a municipal urban cleaning or waste collection rate that covers more than 40% of

service costs;

! an effective body of municipal regulations applicable to urban cleaning that may be

part of a general body of municipal regulations;

! a political decision on the part of the mayor to recuperate the existing refuse dump,

where applicable, and install a new sanitary landfill;

! the existence of land owned by the municipality that meets the environmental

conditions necessary for installing a sanitary landfill;

! an existing or planned public awareness raising campaign on environmental issues

in general or urban cleaning in particular;

! no depositing of industrial waste in the landfill.

13.9.5 General considerations

The relation between sanitary landfills and carbon credits is based in the fact that

landfill biogas capture and utilization projects, involving burning and transformation

into CO2, are less onerous than other GHG emission reduction options. Such sanitary

landfill projects are therefore likely to be of interest to large international corporations

as a way of obtaining cheaper CERs.

Even though income from CERs is not received immediately after the transformation

of a refuse dump into a sanitary landfill, in the medium term it can represent real financial

assistance for municipalities enabling them to ensure the correct operation of urban

254

solid waste final disposal installations. This offers municipalities a definitive and low

cost way of fulfilling their constitutional and moral duty to appropriately dispose of

waste produced in urban concentrations and provide basic sanitary conditions for the

inhabitants of the city they administer.

Finally it should be noted that the Intergovernmental Panel on Climate Change has

recently approved a new methodology for calculating the emissions avoided by

composting processes. This is of interest as it can facilitate the viability of projects

that add this form of waste treatment to the operation of sanitary landfills thus

extending their useful life, reducing leachate generation and avoiding methane emissions,

which can lead to CER income.

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ABNT – Brazilian Institute of Technical Standards

ASCE – American Society of Civil Engineers

BOD – Biochemical Oxygen Demand

CEPIS/PAHO – Pan American Center for Sanitary Engineeringand Environmental Sciences

CER – Certified Emission Reduction

CDM – Clean Development Mechanism

CNEN – National Nuclear Energy Commission, Brazil

COD – Chemical Oxygen Demand

COMLURB – Rio de Janeiro Urban Cleaning Company

CONAMA – National Commission on the Environment, Brazil

EIS – Environmental Impact Study

EMS – Environmental Management Secretariat, IDRC

GHG – Green-House Gas

HDI – Human Development Index

HDPE – High Density Polyethylene

IADB – Inter-American Development Bank

IBAM – Brazilian Institute of Municipal Administration

IDRC – International Development Research Centre of Canada

IPCC – Intergovernmental Panel on Climate Change

IPE – Individual Protection Equipment

ISWM – Integrated Solid Waste Management

ISWMP – Integrated Solid Waste Management Plan

LAC – Latin America and the Caribbean Region

LDPE – Low Density Polyethylene

MoU – Memorandum of Understanding

NGO – Non-Governmental Organization

PAHO – Pan-American Health Organization

PET – Polyethylene Terephtalate

PVC – Poly Vinyl Chloride

Rio 92 – United Nations International Conference on Environmentand Development (Rio de Janeiro, 1992)

SISNAMA –National Environmental System, Brazil

TGW –Total Gross Weight

UN – United Nations

VDC – Voluntary Drop-off Centres

WCR – Waste Collection Rate

GLOSSARY OF ACRONYMS

259

GLOSSARY

Biogas: combustible gas naturally generated during the organic matter putrefaction process.

Clean technology: technology that does not produce secondary effects or impact on the

environmental balance or natural systems.

Compensatory measures: measures to compensate communities or social groups for

the use of non-renewable environmental resources, or for unavoidable negative environmental

impacts.

Composting: procedures for the transformation of biodegradable organic municipal solid

waste into organic compounds.

Domestic waste: residential waste and waste from small commercial generators.

Environmental impact assessment: a procedure aimed at identifying and interpreting the

effects of public or private actions or projects that may cause environmental impacts or

alter the quality of life.

Final disposal: the final process applied to solid waste resulting in its ultimate placement.

Governing plan: a fundamental legally binding policy instrument for the development and

organization of the municipal territory aimed at guaranteeing an appropriate social functioning

of the city.

Greenhouse effect: the absorption by the Earth’s atmosphere of infrared radiation emitted

by its surface, resulting in increased heat on the Earth’s surface and thus an increase in the

average temperature of the planet. This phenomenon stops heat from the sun leaving the

atmosphere and returning to space, replicating on a planetary scale an effect similar to the

one observable in a greenhouse.

Healthcare institutions: public and private hospitals, laboratories, clinics, veterinary clinics,

medical centres and all other establishments where any level of human or animal healthcare

is practiced with a view to prevention, diagnosis, treatment or rehabilitation.

Indivisible service: a public service available to all tax-payers that cannot be measured

on the basis of the amount used by individual citizens.

Integrated solid waste management plan: a technical planning instrument for activities

linked to urban cleaning.

Intermediary agents: agents involved in the commercialization of recyclable materials in

general as intermediaries in sales by segregators to recycling companies, which implies a

reduced financial income for segregators.

260

Leachate: liquid that drains through solid waste, contains materials in solution or in

suspension and results from the decomposition process plus the infiltration of rainwater.

Master plan: a document containing all of the necessary elements for the complete

implementation of a project in accordance with relevant technical regulations.

Medical waste: all waste generated by healthcare institutions.

Municipal Treasury: the resources of a municipality out of which the municipal budget is

financed.

Municipal waste: solid or semisolid waste generated by activities in population centres, of

residential, commercial or institutional origin, or from markets, healthcare institutions, small

industries and the sweeping and cleaning of public spaces.

Organic law: a municipality’s foundational law defining the areas of jurisdiction and

responsibility for its executive, legislative and judicial branches.

Plant: a solid waste processing site including the land, structures, works and added features.

Recycling company: a company specializing in the recycling of material.

Refuse: all waste produced by human activity that is not reused.

Refuse dump: a place where waste is indiscriminately dumped in the open air without the

application of any sanitary treatment.

Segregator: a person engaged in the separation of recyclable material from refuse, also

called scavenger or waste picker.

Solid waste management: all technical and administrative activity, including planning, design

and evaluation, that is related to appropriate solid waste management.

Urban cleaning service: all activities relating to solid waste management: preparation

and storage, collection, transport, transfer, street cleaning, recyclable material recovery,

treatment and final disposal of solid waste.

Documents

Integrated Municipal Solid Waste Management Manual - Brazil