Hazardous Waste Management:Overview

Waste Management

Definition of Hazardous Waste

A solid or liquid wastes which because of its quantity, concentration or physical, chemical or infectious characteristics, may:

1. Cause increase in mortality or severe illness,

2. Pose a substantial potential hazard to human health or environment, when improperly treated, stored, transported or disposed

Definition of Hazardous Waste

Characteristics of Hazardous Waste

Ignitability (flash point >60oC)

Corrosivity (pH <2 or >12.5)

Reactivity (unstable materials or material that cause violent reaction when in contact with another material)

Toxicity (Leachate Test)

Nature of Hazardous Waste Management

Hazardous Waste field is interdisciplinary

Requires professionals with diverse background working together to solve the complex issue of hazardous waste management

Environmental Impact and Risk Assessment

Treatment, Storage and Disposal

Waste Minimization, Recycling and Reduction

Management and Cost

Past Disposal Practice

Soil Spreading

Pits/Ponds/Lagoons

Sanitary Landfills

Drum Storage Areas

Underground Storage Tanks

Midnight Dumping

Uncontrolled Incineration

Waste Generation Rates By Industry

Chemical Products Electronics

Petroleum & Coal Products Primary Metals

Transportation Equipment All Other Industries

Typical Hazardous Waste Types

70%

25%

Inorganic Liquid Organic Liquid Sludge

Why the need for HWTC?

Protect public health and the environmentReduce impact of hazardous waste on surface water and ground waterProvide the means to enhance:

Waste minimization at various industrial operations, andWaste recycling

Objectives of HWTC 1. Avoid and minimize environmental

and health pollution risks associated with the generation, storage, collection, transport, handling, recycling, and disposal of hazardous wastes

2. Ensure the movement and disposal practice of hazardous wastes is always controlled and environmentally safe, flexible, and economically sustainable for local conditions

Technical Feasibility Can the wastes be

separated at source to avoid co-mingling and analyzed before shipping to the facility?

What characteristics are the separated wastes likely to have?

What quantity of the wastes should be considered as wastewater?

Market and Economic Feasibility Is there a local market for the products

of recycling? Is there an international market for the

products of recycling?What scale of disposal fees is to be

expected for each category of waste?What rate of return would a Private

Sector investor expect for providing and operating a Hazardous Waste Recycling Facility?

Materials Disposed in HWTC Liquid organic wasteOily sludge and residue from petroleum industry Spent oil and catalystsContaminated soil Liquid heavy metalsAcidic and basic solids and liquids Liquid ammonia and ureaOff-Specification products

Estimation of Hazardous Wastes Quantities??

Hazardous Waste Inventory:

Estimate the total waste stream quantityDeduct the portion of these wastes that are being recycled or processed at the generator’s own facilitiesDeduct any co-mingled wastes that are impossible to separate in a cost-effective manner

Estimation of Hazardous Wastes Quantities (cont.)

Deduct waste quantities being disposed without permitPrepare an integrated treatment system for the remainder with add-on facilities for growth and improvement in anticipation of reducing any unauthorized disposalPropose action as necessary for treatment and disposal facilities for the co-mingled and improperly disposed wastes

HWTC Design Approach

1. A flexible modular design will provide the Project Authority with the opportunity to attract private sector investments and will minimize capital cost in the long-term

– Focus initially on the major polluters– Provide HWTC to treat part of the waste– Initiate and monitor

HWTC Design Approach (cont.)

2. Due to the nature of the hazardous wastes and their potential to change characteristics and properties over time, the HWTC needs to be properly designed and equipped with facilities that are capable of safely meeting the needs of handling and disposing the hazardous waste

Description of the HWTC

Liquid Waste Treatment FacilityLand Farming FacilityClass I Hazardous Waste LandfillClass II Regular Waste Landfill Solidification and Stabilization UnitIncinerator

Important Points

The priorities of hazardous Waste management in decreasing order of importance:

Minimization/Prevention

Treatment/Remediation

Disposal

Liquid Waste Treatment Facility

Separate tank farm storage for acidic and basic waste as well as drum storage areaNeutralization reactorsSludge storage reactorStandby neutralization reactors to be used during maintenance

Activated Carbon Column

Liquid Phase Adsorption Treatment System

Industrial Wastewater Treatment

Chemical Oxidation

In general the objective of chemical oxidation is to detoxify waste by adding an oxidizing agent to chemically transform waste componentsChemical oxidation is a well established technology that is capable of destroying a wide range of organic molecules, including chlorinated VOCs, phenols and inorganics such as cyanide

Process Description Chemical Oxidation is based on the delivery of oxidants to contaminated media in order to either destroy the contaminants by converting them to innocuous compounds commonly found in nature

The oxidants applied are typically hydrogen peroxide (H2O2), potassium permanganate (KMnO2), ozone (O3)

Process Description

Land farming is the preferred technology for the treatment of oily sludge and hydrocarbon contaminated soils, which constitute the main component of hazardous organic wastes to be treated at the HWTC

Land Farming Facility

Base Liner Detail

SUBSOILGEOMEMBRANE

WASTE

FILTER SOILGRAVEL W/PERFORATED PIPE

Compounds to be treated at the land Farming Facility:

Volatile Organic Compounds (VOCs): benzene, ethylbenzene, toluene, xylenes;

Semi-Volatile Organic Compounds (SVOCs): phenols, creosol, naphthalene, phennathrene, benzo(a)pyrene, flourrene, anthracene, chrysene; and

Heavy Metals: chromium, cyanides, lead and nickel

Land Farming Facility (cont’d)

Aerobic Biodegradation

ORGANICPOLLUTANT + MICROORGANISMS + NUTRIENTS + OXYGEN

CARBON DIOXIDE + WATER + BIOMASS

HYDROCARBONPRODUCT

Microorganisms

• Regarding the natural breakdown of hydrocarbon products, bacteria are the main microorganism in the bioremediation process

• Bacteria act as decomposers and utilize hydrocarbon product as a source of energy

Nutrients

Nutrients enhance the biodegradation process by supplying essential elements required for optimal microbial growth and maintenance

Nutrients can be supplied in the field through the application of manure or fertilizer

C:N:P = (100-300):10:1

Requirements for Biodegradation

Proper nutrient balance Temperature 15 – 30 oCAcceptable pH 5.5 - 8.5Moisture content of 60% - 80% of

field capacityOxygen concentrationPresence of toxic heavy metals

Naphthalene Removal Efficiency

0

20

40

60

80

100

0 100 200 300 400

TIME (hours)

AV

ER

AG

E N

AP

TH

AL

EN

E

RE

MO

VA

L E

FF

ICIE

NC

Y (

%)

Non-Acclimatized Acclimatized Control

Bio-piles

Soil Composting

Hazardous Waste Landfill

Class I Landfill should include:

Double liner Leachate collection Leachate detection

system Surface water

control mechanism Impermeable cover

system

Hazardous Waste Landfill

Hazardous Waste LandfillLiner System

Regular Waste Landfill

Class II Landfill should include:

Single liner Leachate

collection Surface water

control mechanism Impermeable

cover system

Regular Waste Landfill

Solidification and Stabilization

The solidification and stabilization facility (SSF) will be designed to inactivate and immobilize contaminants prior to landfilling

Solidification and Stabilization

The following waste will be processed by SSF plant prior to landfilling:

Mercury contaminated solid wastes;

Solid miscellaneous inorganic sulfur;

Semi-solid hazardous waste; and

Sludge from Liquid Hazardous Waste Treatment

Solidification and StabilizationS/S reduces the mobility of hazardous substances and contaminants in the environment through both physical and chemical meansS/S seeks to trap or immobilize contaminants within their host medium (i.e. soil, sand and binding agent)Leachability testing is usually performed to measure the immobilization of contaminants from the stabilized matrix

Solidification and Stabilization

• General binding and sorbent materials: Cement Pozzolans Lime Silicates Organically

Modified Clays

High Temperature Thermal Desorption

HTTD is a technology in which wastes are heated to 320 to 560 oC Produce final contaminant concentration level below 5 mg/kg

Incinerator

Structure to house the furnace

Tipping floor where the Hazardous Waste is disposed

Storage pit to store the Hazardous Waste delivered

Charging system

Furnace

Air pollution control

Ash handling system

HWTC Control Philosophy

Provide a Supervisory Control and Data Acquisition (SCADA). The SCADA system will provide two levels of control:

Level 1 control operates equipment directly and bypasses all interlocks.

Level 2 is initiated directly by computer programming. Level 2 controls, operates equipment and processes remotely.

Typical Control System

Environmental Monitoring

Air Quality Groundwater

Quality Surface Water

Quality Dust and Noise

Environmental Monitoring

Selection of the parameters of concern

Sampling methodology

Quality assurance /quality control plan

Project Approach

Task 1: Review of Existing Data

Task 2: Discussion with Project Authority

Task 3: Development and Finalization of HWTF Design

Task 4: Prepare Final Design Drawings and Design Basis Memorandum

Project Approach (cont.)

Task 5: Design of Liquid Hazardous Waste Treatment Facility

Task 6: Class I and II Landfills Design

Task 7: Land Framing Facility Design

Task 8: Solidification and Stabilization Facility Design

Project Approach (cont.)

Task 9: HWTC Construction

Task 10: Facility Commissioning and Operation

Task 11: Facility Handing Over

Conclusions

1. Key to proper design of HWTC is system flexibility to adjust to hazardous waste quantities and properties over time

2. Enforcement of environmental law and regulations

Leachate Treatment Using Wetlands

Department of Environmental Engineering Beijing University of Chemical Technology December 2003

Wetlands

Wetland is define as land having the water table at, near or above the land surface or which is saturated for long enough period to promote wetland or aquatic processes as indicated by hydric soils, hydrophilic vegetation, and various kinds of biological activity which are adapted to the wet environment.

Treatment Mechanisms in a Wetland System

Type of Engineered wetlands

Constructed wetland systems are classified into

two general types: Horizontal Flow System (HFS)

Surface Flow (SF) Sub-surface Flow (SSF)

Vertical Flow System (VFS).

Horizontal Flow Wetland System

Surface Flow Wetland System

Subsurface Flow Wetland System

Field Monitoring

Monitoring wells

Pond #1

Pond #2Peat Filter

SW-1

SW-4SW-3

SW-2

DBA

C

FSW-1

FSW-2

FSW-3

W-2

W-1

MW-4

MW-1

MW-2

MW-5MW-3

Manhole

Pump

Field Monitoring

Boron Concentration

0

2

4

6

8

10

12

14

16

189

6-1

96

-2

96

-3

96

-5

96

-6

96

-7

96

-8

97

-1

97

-2

97

-3

97

-4

97

-5

97

-6

Monitoring Event

Co

ncen

trati

on

(m

g/L

)

Pond MW-A MW-B MW-C MW-D SW

Field Monitoring

Boron adsorption was directly related to organic content

Peat filter was effective in treating landfill leachate

The adsorption capacity of the peat can be significantly enhanced by lime addition

Conclusions