LESSON 2: CHARACTERISTICS AND QUANTITY OF MSW
Goals
Determine why quantification is important
Understand the methodology used to quantify MSW
Become aware of differences among global production rates
Understand factors affecting waste generation rates
Become familiar with per capita generation rates
Goals, Cont’d
Explain why it is important to characterize MSW.
Become familiar with MSW descriptors.Understand the methods used to
characterize MSWDescribe the physical, chemical, and
biological properties associated with MSW.
Perform calculations using waste composition and properties.
RCRA Subtitle D Wastes
MSWHousehold
hazardous wastesMunicipal sludgeNon-hazardous
industrial wastesCombustion ash
SQG hazardous waste
Construction and Demolition debris
Agricultural wastes
Oil and gas wastes Mining wastes
MSW - RCRA Definition
Durable goodsNon-durable goodsContainers/PackagingFood wastesYard wastes Miscellaneous inorganics
MSW - Textbook Definition
Mixed household waste recyclables household hazardous waste commercial waste yard waste litter bulky items construction & demolitions waste
What are the sources of RCRA Subtitle-D Wastes? Residential Commercial Institutional Industrial Agricultural Treatment Plants Open Areas (streets, parks, etc.)
What is the Nature of Municipal Solid Wastes?OrganicInorganicPutrescibleCombustibleRecyclableHazardousInfectious
Importance of Generation RatesCompliance with Federal/state
diversion requirementsEquipment selection,Collection and management
decisionsFacilities designMethodology
– Materials Flow– Load Count
Factors Affecting Generation Rates Source
reduction/recycling Geographic location Season Home food waste
grinders Collection
Frequency GNP trend, Per
capita income
Legislation Public attitudes Size of households Population density Pay-As-You Throw
Programs Population
increase
EU Waste Generation Study Studied correlation between waste generation
and:– Population– Population density– Age distribution– Employment– GDP– Infant mortality– Life expectancy– Average household size– Unemployment– Tourism
Waste generation has grown steadily in Europe for over 20 years
Strongest Correlation
Generation increases with: – Population– Age distribution (fraction in 15-39,
employment)– The rate of increase in GDP (for example
Poland, Spain and SlovakiaGeneration decreases with average
household size Low income areas had low amounts of
plastics, paper and cardboard, but not organics
Conclusions
Continued increase in MSW generation rate is expected– Because of economic grown– Improving health– Increasing urbanization– Offset by declining percent of 15-59
year olds
Composition Studies
Materials FlowManual Sorting
Manual Sorting Methodology Study PlanningSample PlanSampling ProcedureData Interpretation
Sample Plan
Load SelectionNumber of Samples
Sampling Procedure
Vehicle UnloadingSample Selection and RetrievalContainer PreparationSample PlacementSorting
Waste contents areunloaded for sorting
Appropriate mass of material is selected randomly
Each load is separated manually by component example - Wood, concrete, plastic, metal, etc.
Components are separated
Each component is weighed and weights recorded
Data Interpretation
Weighted Average based on Generator Source Composition/Distribution
Contamination Adjustment
US MSW Composition
Terminology
Generated Waste = Disposed (Collected) Waste + Diverted
Waste
Specific Weight
Values: 600-900 lb/yd3 as delivered
Function of location, season, storage time, equipment used, processing (compaction, shredding, etc.)
Soil Phase Diagram
Vsample=Vsolids+Vliquid+Vgas
Vvoids = Vliquid + Vgas
Wsample=Wsolids+Wliquid
(Wgas~0.00)
V=volume, W=weight or mass
Moisture content (MC)
Weight or volume basedWeight: wt. of water/sample wt.
• MCwet= Wwater/(Wwater+Wsolids)
• MCdry= Wwater/Wsolids
Volume: Vwater/Vsample
Chemical Composition
Used primarily for combustion and waste to energy (WTE) calculations but can also be used to estimate biological and chemical behaviors
Waste consists of combustible (i.e. paper) and non-combustible materials (i.e. glass)
Proximate Analysis
Loss of moisture (temp held at 105o C)
Volatile Combustible Matter (VCM) (temp increased to 950o C, closed crucible)
Fixed Carbon (residue from VCM)Ash (temp = 950o C, open crucible)
Ultimate Analysis
Molecular composition (C, H, N, O, P, etc.)
Table in notes
Typical Data on the Ultimate Analysis - ExampleFood Wastes
– Carbon: 48%– Hydrogen: 6.5%– Oxygen: 37.6%– Nitrogen: 2.6%– Sulfur: 0.4%– Ash: 5%
Energy Content
Models are derived from physical composition and from ultimate analysis
Determined through lab calculations using calorimeters
Individual waste component energy contents
Empirical Equations
Modified Dulong formula (wet basis):BTU/lb = 145C +610(H2-02/8)+40S +
10NModel based on proximate analysis
Kcal/kg = 45B - 6WB = Combustible volatile matter in MSW (%)
W = Water, percent weight on dry basis
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Last updated April 18, 2023 by Dr. Reinhart