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SOLID WASTE MANAGEMENT

M.Sc Environmental Design

ALLAMA IQBAL OPEN UNIVERSITY ISLAMABAD

January 25, 2014

Muhammad Abid

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Solid Waste Management - History

Waste treatment and disposal has been motivated by concern for

Public Health.

Migration of People started due to Industrial Revolution between

1750 and 1850.

Massive expansion of the population living in towns and cities,created high volume of domestic, commercial and industrial

waste i.e. broken glass, rusty metal, food residue and human

waste, which was dangerous to human health.

Waste attracted flies, rats and other vermin, which in turn posedpotential threats through the transfer of disease. This led to an

increasing awareness of the link between public health and the

environment.

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SWM is potential threat to human health, legislation wasintroduced on a local and national basis in many countries.

Waste treatment and disposal has been motivated by

concern for public health.

Introduction of Acts (UK 1875/1936) - Removal andDisposal of Waste and into Water

In USA Acts were introduced in 1795, 1856

Purpose built municipal waste Incinerators were introducedin the UK in the late 1870s and by 1912 there were over 300

waste incinerators in the UK, of which 76 had some form of

power generation

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Incineration plants reached the end of their operationallifetime, they tended to become scrapped in favor of

landfill.

Environmental implications of merely dumping the waste

in open sites and later with increase waste began to beburied.

Burying the waste had the health advantages of reducing

odours, and discouraging rats and other vermin. Series of incidents in the late 1960s and 1970s highlighted

waste as a potential major source of environmental

pollution.

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Solid Waste Management - Pakistan

In Pakistan SWM, need increased for using disposableitems i.e. plastic bags etc., which cause drainage

problems.

In Karachi - 50% of the citys daily generation of 7,000

tons of rubbish - Collected by the Municipal service,

while the rest remains at collection points and on Dump

sites

Urban environment in Pakistan continues to deteriorate,there is growing recognition of the need for a Sanitation

policy with sound operational strategies.

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Informal Recycling of Domestic WasteTwoCategories:

Waste picking in streets, communal bins, transfer

points and disposal sites.

Waste separation at the household stage and selling

onto itinerant waste buyers.

Above waste passes through a #of dealers in trading

and recycling, before it reaches the recycling industry.

The SWM system starts from the Households and ends

with the disposal or reuse of the materials

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Informal Sector

There are independent operators dealing in waste collection,

purchase, separation, restoration, and resale and recycling

Kabaris are large-scale waste dealers who operate from

shops and warehouses. There are approximately 1,000 inKarachi and most specialize in just one type of waste, which

they buy at auctions or from middle dealers and resell to

recycling plants, or recycle themselves.

Waste Busters collect rubbish from households and charge

about PKR 200 a month

Few Local NGOsCrush vegetables to produce liquid

concentrate for pesticides, fertilizer and Bin designs

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Recycling Waste Materials

Waste Material Common Reuse and RecyclingBroken glass Glass bottlesBottles Washed and used againBread Livestock feedNewspapers Various types of packingFerrous metal Recycled in re-rolling millsPaper Cardboard etc.Aluminium Re-melt in moulds for various industriesPlastics Uses/recycling depends upon type: toys, shoe soles, shopping bags, sandals

etc.Plastic bags Buckets and other household containersMagazines, books Sold again at reduced prices

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Cleaner Production Opportunity for

the Industrial Sector of Pakistan Industrial Sector in Pakistan accounts for 18% of GDP

Environmental Degradation due to the uncontrolled and

inefficient use of natural resources, low industrial

productivity, excessive generation of hazardous waste and

the uncontrolled release of solid wastes, air pollutants anduntreated wastewater into the natural environment has

become a major problem in Pakistan.

The major Polluting Industries are tanneries, textile,

petroleum, pesticides, fertilizer etc.

Majority of the multinational companies in Pakistan are also

now going for certification due to their corporate policy.

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Cleaner Production Opportunity for

the Industrial Sector of Pakistan Till now 20 to 25 companies have achieved ISO 14000

certification, mostly multinationals, whereas remaining are

exportbased industries.

Most of the Local Companies are still reluctant towards due

to wrong perception that environmental solutions cannot beeconomically viable.

Lack of expertise available locally, there is a critical need

for capacity building program for pollution control,

promotion of environmentally sustainable development and

creation of awareness

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Cleaner Production Opportunities

for Industries Cleaner Production Opportunities for Industries

Cleaner production (CP) is a strategy for enhancing productivity and

environmental performance for socio-economic development.

Application of Appropriate Techniques, Technologies and

Management Systems to produce environmentally compatible goodsand services.

Improvements in productivity and environmental performance

achieved through CP bring bottom line savings, profit/efficiency.

In-house improvements and CP technologies will not only result inthe improvement of economic and environmental performance of the

unit, but will also reduce the cost of end-of-pipe treatment.

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for Industries Cleaner Production Opportunities for Industries

Cleaner Production technologies already used in the country

Scrubbers

Dust Filters

Economizer

Vacuum Cleaners

High Pressure Cleaning Devices

Condenser

Grease Trap

Incinerators

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for Industries Waste

The definition of waste can be very subjective; what represents waste to one person

may represent a valuable resource to another

Definition of 'Waste' Production or consumption residues not otherwise specified below.

Off-specification products.

Products whose date for appropriate use has expired. Materials spilled, lost or having undergone other mishap, including any materials, equipment etc. contaminated as a

result of the mishap.

Materials contaminated or soiled as a result of planned actions (e.g. residues from cleaning operations, packing

materials, containers etc.).

Unusable parts (e.g. reject batteries, exhausted catalysts etc.).

Substances which no longer perform satisfactorily (e.g. contaminated acids, contaminated solvents, exhausted tempering

salts etc.).

Residues of industrial processes (e.g. slags, still bottoms etc.).

Residues from pollution abatement processes (e.g. scrubber sludges, baghouse dusts, spent filters etc.).

Machining or finishing residues (e.g. lathe turnings, mill scales etc.).

Residues from raw materials extraction and processing (e.g. mining residues, oil field slops etc.).

Adulterated materials (e.g. oils contaminated with PCBs etc.).

Any materials, substances or products whose use has been banned by law. Products for which the holder has no further use (e.g. agricultural, household, office, commercial and shop discards etc.).

Cl P d i O i i

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for Industries Types of Waste

Controlled Waste

Household Waste

Industrial Waste

Commercial Waste Clinical Waste

Special Waste

Un-Controlled Waste

Inert Waste

Hazardous Waste

Municipal Solid Waste

Cl P d ti O t iti

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for Industries Waste Classification Systems

Origin, e.g., clinical wastes, household or urban solid wastes, industrial wastes,

nuclear wastes, agriculture;

Form, e.g., liquid, solid, gaseous, slurries,

powders;

Properties, e.g., toxic, reactive, acidic,alkaline, inert, volatile, carcinogenic;

Legal definition, e.g., special, controlled,

household, industrial, commercial.

Properties of Waste

Series of descriptors for different types of

wastes:

Code DescriptionHI ExplosiveH2 OxidizingH3A Highly flammable

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for Industries Subdivisions of General HHs, Commercial and Industrial Waste Category:

General household, commercial and industrial waste

Separate components of general waste

Vegetable matter

Animal matter

Animal or vegetable oil, fat, wax, grease Sewage

Subdivisions of the Organic Chemical Wastes Category:

Paints, resins and adhesives

Inks and dyestuffs

Cosmetics, Surfactants and Chelating Agents

Monomers and Precursors, Tarry wastes

Pharmaceuticals , Pesticides

Organic Chemical Process Wastes, Additional Codes

Cl P d ti O t iti

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for Industries Typical Composition and Properties of Sewage Sludge

PropertyTypical value

Calorific value 21.3

MJ/kg (dry, ash free)Ash content

37%Composition of combustible fraction (dry, ash free)Carbon

53.0%Hydrogen

7.7%Oxygen

33.5%Nitrogen

5.0%Sulphur

0.8%Organic composition (dry, ash free)Crude protein

30.0

Crude fat

13.0Crude fiber

33.0Non-fibrous carbohydrate 24.0

Cl P d ti O t iti

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for Industries Physical form of the Waste

Physical form of the waste i.e solid, liquid or sludge etc:

F1 Solid - composite of materials

F2 Solid - mixed materials

F3 Solid - bulky

F4 Liquid - containerized F5 Liquid - bulk

F6 Sludge/slurry - in a solid container

F7 Sludge/slurry - bulk

For Textiles

F8 Clean textiles F9 Dry textiles

For Metals

FI0 Metal rod F11 Metal swarf F12 Metal wire

For Plastic

F 13 Plastic bottles F14 Plastic film F15 Plastic - rigid

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Waste Containers and Collection System

Type of container used to store the waste generated from households, commercial and

industrial premises depends on i.e. frequency, efficiency of collection, amount of waste,

type of housing, density of collected wastes, collection vehicle type, vehicle usage and

manpower and economics relating to container and the collection system.

The correct size of waste container is important, since it has been shown that the use of

non-standard containers is the greatest cause of litter. Household waste containersinclude traditional metal or plastic dustbins, wheeled bins and plastic sacks. The capacity

of the household waste storage container depends on how many collections are made per

week.

With a general increase in the amount of waste generated, there has been a response to

use bigger or more containers, which also has the potential to reduce manning costs byless frequent waste collections.

Another factor dictating size of container and frequency of collection is climate; in

cooler areas such as Northern Europe, where odour from the degradation of the waste

occurs more slowly, the frequency of collection may be once or twice per week.

Consequently the container must be able to store a full week's volume of waste.

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Waste is dumped un-segregated and collected by three methods:

Hauled Container System,

Stationary Container System and Bull Carts,

The containers are mostly transported from one place to another with help of a truck or

tractor, which is overflowing and not covered properly. The waste spills out of the

container and a lot of it falls in the streets before reaching the landfill site. Similarly, in

certain areas bull and donkey carts are used to collect the MSW. The cart goes from

street to street picking up the waste and is again not a proper system for waste collection.

A fact sheet on Municipal Solid Waste Management (MSWM) has been developed by

WWF-P with a viewpoint to facilitate the readers on efficient practices of SWM.

The government has initiated a plan to privatize the MSWM in the country. This could

be done using the present network of recyclers and scavengers to collect and processgarbage. It would be in their interest to make arrangements with individual households

and industries to segregate different recyclable at the source. This interest of the private

collector in segregated garbage could be translated in payment in terms of free garbage

collection or cash payment for the segregated material.

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Land-Fills

Landfilling is the technical term used to Fill large holes in the ground with waste.

This process is also known as land-raising. Landfill sites produce landfill gas (55%

methane and 45% carbon dioxide) which can be partly captured for energy production.

Impacts

Friends of the Earth opposes landfill for the 80% of municipal solid waste that can berecycled or composted for the following reasons:

It wastes valuable resources.

It exacerbates climate change because when materials are buried, more fossil fuel energy

is used to replace the products through mining, manufacturing, and transportation around

the world. It produces methane, a potent greenhouse gas that contributes to climate change.

It creates water pollution through leaching.

It can lead to the contamination of land.

It gives rise to various nuisances including increased traffic, noise, odours, smoke, dust,

litter and pests.

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Major Advantageswith Landfillingof wastes are the low costs of landfill

compared to other disposal options and the fact that a wide variety of wastes aresuitable for landfill. It should also be remembered that ultimately, many other waste

treatment and disposal options require that the final disposal route for the residues

requires landfill.

Disadvantages with Landfill. Older sites, which in some cases are still in use or

have long been disused, were constructed before the environmental impacts ofleachate and landfill gas were realized.

Landfill gas, in particular, can be hazardous, since the largest component, methane,

can reach explosive concentrations.

All Landfill sites are required to be monitored for landfill gas, and the gas from

operational sites must be controlled via proper venting. Landfill methane gas is alsoa 'greenhouse gas', leading to the problems of global warming but with about 30

times the effect of carbon dioxide.

Selection of a site for a waste landfill depends on a wide range of criteria, including

the proximity of the site to the source of waste generation, suitability of access

roads, the impact on the local environment of site operations, and the geological andh dro eolo ical stabilit of the site.

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Main aim of the landfill site assessment investigation is the identification of the

possible pathways and receptors of landfill gas and leachate in the surroundingenvironment and the environmental impact of site operations Site assessment

involves appraisal of geological and hydrogeological conditions at the site.

This may include the use of existing surveys, aerial photography, boreholes,

geophysical investigations, geological mapping and sampling etc. The information

allows an assessment of soil and bedrock grain sizes, mineralogy and permeabilitys,and ground water levels.

Inaddition, the previous use of the site, meteorological data, transport infra-structure

and planning use designations, and the planning strategy of the area would also be

assessed.

For large landfill sites an environmental assessment is also required to determine theimpact on the environment. Environmental assessment involves a description and

assessment of the direct and indirect effects of the project on human beings, fauna,

flora, soil, water, air, climate and landscape, material assets and the cultural heritage

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Considerations for Landfills

A waste landfill is a major design and engineering project and there are a number ofpoints to be considered as part of the process.

Final Landform Profi le

Site capacity

Settlement

Waste density

Mater ials requirements

Drainage

Operational Practice

The typical modern landfill site consists of a secure, fenced, landscaped site with

access routes for waste transport vehicles. The sequence of operations for an

incoming waste vehicle may include the weighing of the lorry on a weighbridge

document inspection and waste inspection. Once cleaned, the lorry would move to

the waste disposal area where the waste is tipped, the wheels of the lorry are cleaned

and the lorry is weighed out if the site to determine the weight of waste deposited.

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Types of Waste Land Filled

Inert wastes

Bio-reactive wastes

Hazardous/industrial or special waste

Factors Influencing Waste Degradation in Landfills

Site characteristics

Waste characteristic

Moisture content of the waste

Temperature

Acidity

Major Stages of Waste Degradation

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Major Stages of Waste Degradation

in Landfills

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Landfill Design Types

Attenuate and disperse landf i l ls

Containment landfi l ls

Schematic diagram of water balance for an attenuate and disperse landfill site.

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Landfill Gas

Gases arising from Bio-degradation landfills consist of hydrogen and carbon dioxide

in the early stages, followed mainly by methane and carbon dioxide in the laterstages. What is known as 'landfill gas' is a product mainly of the methanogen stage

of degradation of biodegradable wastes.

Landfill gas is produced from household and commercial wastes, which contain a

significant proportion of biodegradable materials however, certain industrial and

commercial wastes, which have been estimated to contain 62% and 66%biodegradable components.

The major constituents of landfill gas, methane and carbon dioxide are odorless, and

it is the minor components such as hydrogen sulphide, organic esters and the

organosulphur compounds, which give landfill gas a malodorous smell. Landfill gas

contains components, which are flammable, and when mixed with air can reachexplosive concentrations in confined spaces.

Some of the trace components of landfill gas have a toxic effect and may be

hazardous if high enough concentrations are reached; for example, hydrogen

sulphide Aromatic hydrocarbons are in low concentration but may potentially have

an adverse effect on the workforce of the landfill site.

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Landfill Gas

The major components of landfill gas, methane and carbon

dioxide, are 'greenhouse gases'. The greenhouse effect is

produced by certain gases in the atmosphere, which allow

transmission of short wave radiation from the sun but are

opaque to long wave radiation reflected from the earth'ssurface, thereby causing warming of the earth's atmosphere.

A molecule of methane has approximately 30 times the

greenhouse effect of a molecule of carbon dioxide.

The quantities of gas produced from waste depend on the

biodegradable fraction of the waste, the presence of

microorganisms, and suitable aerobic and anaerobic

conditions

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Landfill Gas Migration

Gases generated in the landfill will move throughout the mass of waste in

addition to movement or migration out of the site. The mechanism of gasmovement is via gaseous diffusion and advection or pressure gradient.

That is, the gas moves from high to low gas concentration regions or

from high to low gas pressure regions.

Movement of gas within the mass of waste is governed by thepermeability of the waste, overlying daily or intermittent cover, and the

degree of compaction of the waste. Lateral movement of the gases is

caused by overlying low permeability layers such as the daily cover and

surface and sub-surface accumulations of water.

Vertical movement of gas may occur through natural settlement of the

waste, between bales of waste if a baling system is used to compact and

bale the waste, or through layers of low permeability inert wastes such as

construction waste rubble. Where landfill gas extraction is practiced to

recover the gas for energy use, the gas is collected in gas wells, and

Possible Landfill Gas Migration

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Possible Landfill Gas Migration

Pathways for a Closed Site

Management and Monitoring of

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Landfill Gas

With the recognition of formation of landfill gas and its associatedhazards, and the potential to utilize the energy content of the gas,

the modern landfill site is designed to trap the gases for flaring or

use in energy recovery systems.

However, the priority is for control of the gases to protect theenvironment and prevent unacceptable risk to human health rather

than utilization, and therefore where energy recovery is practiced,

there would also be a control system alongside.

Three types of system used to control landfill gas migration: Passive venting;

Physical barriers;

Pumping extraction systems.


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Landfill Gas

Passive Venting Systemsare only recommended for oldsites in the late stages of gas generation where gas

generation rates are low, or where inert wastes are landfilled

and similarly low, or where negligible rates of gas

generation are found.

The passive venting pit consists of a highly permeable vent

of gravel material encased in a geotextile fabric to prevent

ingress of fine material and reduction of permeability. Construction of the passive venting system may be as

emplacement of the waste proceeds or afterwards by drilling

or excavation into the mass of waste. Typically the vents are

placed at intervals of between 20 and 50 m.


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Landfill Gas

Physical barr iersuse low-permeability barriers of, for example, flexible polymericgeomembranes, bentonite cement or clay, to contain and restrict the gas migration.

Whilst these barriers might form part of a leachate containment system, they are less

effective in containing gas. Coefficients of permeability for gas containment are required

to be lower than 10-9 m/s. Efficiencies of barriers are improved if they are combined

with a means of removing the gas by either passive venting or pumped extraction.

Pumping extraction systemspump the gas out of the landfill. The gas migrates to gas

pits or wells within the waste, which consists of highly permeable gravel, stones or

rubble with a central perforated plastic pipe. The gases pass through the high-

permeability vent to a plain unperforated pipe, which draws the gases through to the

pump. Leachate vapour may also be pumped out with the gas, and because this vapour

has a high moisture content a leachate condensation trap is required. Figure shows atypical pumping extraction well. The gas pumped to the surface is either flared by self-

sustaining combustion or the use of a support fuel, utilized in an energy recovery system,

or if the gas concentrations are sufficiently low it is discharged to the atmosphere. Where

flaring is used to dispose of the gas minimum flame temperatures between 850 and 1100

C are recommended to destroy any hazardous trace components.

Typical combined Leachate and

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Typical combined Leachate and

Landfill Gas Collection Well

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Landfill Leachate Leachate represents the water, which passes through the waste, and water

generated within the landfill site, resulting in a liquid containing suspendedsolids, soluble components of the waste and products from the degradation

of the waste by various microorganisms. The composition of the leachate

will depend on the heterogeneity and composition of the waste and whether

there is any industrial/hazardous waste co-disposal, the stage of

biodegradation reached by the waste, moisture content and operationalprocedures.

The decomposition rate of the waste also depends on aspects such as pH,

temperature, aerobic or anaerobic conditions, and the associated types of

microorganisms. Associated with leachate is a malodorous smell, due mainly

to the presence of organic acids.

The characteristics of the leachate are influenced by the waste material

deposited in the site. For example, inert wastes will produce a leachate with

low concentrations of components, whereas a hazardous waste leachate

tends to have a wide range of components with highly variableconcentrations.

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Landfill Capping Final cover or capping of the landfill site is required after the final waste has been

deposited. The purpose of the cap is to contain and protect the waste, prevent

rainwater and surface water from percolating into the site and influencing the

generation of leachate, control the release of landfill gas, and prevent ingress of air

and disruption of the anaerobic biodegradation process. In addition, the final cover is

landscaped and provides a soil for the establishment of the restored site plant

materials. The design of the cover system of lining materials used to cap the site

depends on the nature of the waste, for example, whether they are inert orbiodegradable.

Overlying the main body of waste may be the gas collection layer, depending on the

nature of the waste. The gas collection layer is a porous material such as geotextile,

geonet or coarse sand through which the gas can easily permeate to the gas

collection and control system.

A barrier layer is a low permeability layer such as a plastic polymer geomembrane, a

geosynthetic clay liner of bentonite/geotextile fabric, or compacted natural clay. The

barrier layer serves a two-fold purpose: to prevent ingress of water and the egress of

landfill gas. The barrier layer may have a protective geotextile layer above and

below.

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Components of Landfill Capping System

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Landfill Site Completion and Restoration

At the end of the life of a landfill, the landfill operator must

demonstrate that the site has physically, chemically and biologicallystabilized and no longer poses a risk to the public or the local

environment. When a site is deemed complete, post-closure pollution

controls and leachate and landfill gas control systems would no longer

be required. Stabilisation is defined in terms of the quantity andcomposition of the leachate and landfill gas produced at the site.

Assessment of completion depends on the type of landfill site. For

example, sites, which have taken only inert wastes, pose a low risk to

human health and the environment since, only low or zero levels of

leachate and landfill gas are likely to be generated. For biodegradable

wastes such as municipal solid waste, then a full assessment of the

leachate composition and gas volume and the potential future

generation rates, together with an assessment of the waste settlement,

would be required

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Energy Recovery

The development of larger and larger landfill sites throughout many countries has

provided for economies of scale and the economic viability of utilization of landfillgas. The modem site is seen in this context as a 'bio-reactor', used to stabilize waste

and produce landfill gas for energy recovery. Therefore, whilst landfill sites exist

which are used for disposal without energy recovery, the modem purpose-built site

would normally incorporate a landfill gas extraction system for the recovery of

energy.

Estimates of the amount of landfill gas generated throughout the lifetime of a

landfill site are highly variable, with estimates of between 39 and 500 m3/tonne.

Annual rates of gas production have been estimated for a typical municipal solid

waste landfill at between 6 and 8 m3/tonne/year, but much higher rates of over 20

m3/tonne/year have been recorded.

The energy recovery technology is based around the gas collection system and the

pre-treatment and power generation technology. Gas collection is via either vertical

gas wells or horizontal well collection systems, depending on the type of site, site-

filling techniques, depth of waste and leachate level. The gas is collected in a series

of perforated gas pipelines connected to a central pipeline.

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Waste Treatment Technologies

Recycling

Recycling is the collection and separation of materials from waste and subsequentprocessing to produce marketable products.

Benefits

Recycling basic materials in order to make new products has several benefits:

It reduces the demand for raw materials by extending their life and maximising the

value extracted from them.

It reduces the habitat damage, pollution and waste associated with the extraction of

raw materials.

It reduces transport costs and pollution from transporting raw materials and

manufacturing new products.

It saves energy in the production process when compared with the energy consumed

in using raw materials.

It reduces emissions to air and water in the production process.

It reduces disposal impact (if more waste is recycled, less waste goes to landfill or

incinerators).

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Composting

The process of composting is one of biological decomposition under aerobic (openair) and thermophilic (at or above 70C) conditions, which breaks down organic

material to leave a humus rich residue, the compost. Compost is a valuable soil

conditioner for both agriculture, gardening and forestry.

Benefits

Composting is an excellent method of managing solid waste with a high organiccontent (i.e. biodegradable waste) such as garden waste, kitchen waste, park waste,

and even scrap paper and cardboard. 60% of municipal solid waste can be

composted.

Composting techniques

Home composting Compost can be made at home using a traditional compost heap,

a purpose designed container or a wormery.

Community composting

Open/Open air windrow

Enclosed/Covered windrow

In-vessel

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Incineration Ration

Incineration is the combustion of waste at high temperatures. It uses a wide variety ofcombustion systems developed from boiler plant technology and also more novel techniques

such as molten salt and fluidized bed incinerators.

Incineration of waste has a number of advantages over landfill

Incineration can usually be carried out near the point of collection. The number of landfill

sites close to the point. of waste generation are becoming scarcer, resulting in transport of

waste over long distances.

The waste is reduced into a biologically sterile ash product, which for municipal solid waste

is approximately one-tenth of its pre-burnt volume and one-third of its pre-burnt weight.

Incineration produces no methane, unlike landfill. Methane is a 'greenhouse gas' and is a

significant contributor to global warming.

Waste incineration can be used as a low cost source of energy to produce steam for electricpower generation, industrial process heating, or hot water for district heating, thereby

conserving valuable primary fuel resources.

The bottom ash residues can be used for materials recovery or as secondary aggregates in

construction.

Incineration is the best practicable environmental option for many hazardous wastes such ashighly flammable, volatile, toxic and infectious waste.

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Incineration - Disadvantages

It generally entails much higher costs and longer pay back periods due to the high capital investment

The incinerator is designed on the basis of a certain calorific value for the waste. Removal of materials such as

paper and plastics for recycling may reduce the overall calorific value of the waste and consequently may affectincinerator performance.

The incineration process still produces a solid waste residue which requires management.

It destroys valuable resources.

It exacerbates climate change because when materials are burned, more fossil fuel energy is used to replace the

products through mining, manufacturing, and transportation around the world. Energy from burning waste is not

renewable. It undermines councils recycling schemes by demanding long-term waste delivery - Because it takes 15-25

years for a waste management company to make a return on their capital investment, the contract between a

council and a waste management company requires the council to provide an agreed amount of waste for at least

25 years.

It produces emissions of nitrogen oxides, particulates, heavy metals and dioxins, all of which are potentially

dangerous to human health.

It produces bottom ash, which may contain heavy metals and dioxins present in the waste burnt, such as

batteries. Bottom ash represents one-third by weight of the original waste and still has to be land filled.

It also produces fly ash (the fine particles and gases caught in the chimney by filter systems), which is

undisputedly toxic, containing pollutants such as heavy metals and dioxins. Fly ash is classified as special waste

(i.e. hazardous waste) and has to be landfilled in very careful circumstances.

It creates very few jobs. The recycling industry however offers enormous potential for substantial job creation.

It is a much more capital-intensive and costly approach than recycling. It creates more noise and traffic. Incinerators can also be re arded as e esores.

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The modern incinerator is an efficient combustion system with

sophisticated gas clean-up which produces energy and reduces the wasteto an inert residue with minimum pollution. Incineration plants may be

classified on a variety of criteria, for example, their capacity, the nature

of the waste to be combusted, the type of system etc. However, a broad

division can be made between mass burn incineration and other types.

Mass burn incineration:Large scale incineration of municipal solid

waste in single-stage chamber unit in which complete combustion or

oxidation occur Typical throughputs of waste are between 10 and 50

tonnes per hour.

Other types of incineration:Other types of incineration involve smallerscale throughputs of between 1 and 2 tonnes per hour of wastes such as

clinical waste sewage sludge and hazardous waste. Typical examples of

such systems include fluidized bed, cyclonic, starved air or pyrolytic,

rotary kiln, rocking kiln, cement kiln, and liquid and gaseous

incinerators.

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Incineration in Pakistan

June 12 was the first World Incineration Day that was observed in Pakistan - whose record onenvironment, solid waste management, health and hygiene of its citizens, is dismal and

pathetic, with the added dilemma that, since its coffers are depleted, whether to invest in such

a contentious technology!

Currently, the majority of hospitals in Pakistan are dumping their waste, which includes both

hazardous and non-hazardous waste, in open grounds just like the municipal waste. This

allows the scavengers to take advantage of anything they may deem valuable, such assyringes, blood bags, catheters, scalpels etc, which they may sell or recycle/ re-use to

deleterious effect. To compound our problem, Pakistan does not have a single sanitary

engineer and in general has been unable to dispose of even the municipal waste with any

worthwhile success. In the light of such an alarming situation, the practice of dumping

hospital waste in open fields is extremely dangerous and hazardous for the health and life of

human beings and nature. Currently, the landfills in Pakistan are just open dumpsites whereanimals graze or scavenge for food and the poor earn their livelihood.

There are 24 incinerators in Pakistan. Only six are operating and that too not according to the

international standards. Resultantly, the process of incineration is not being carried out

properly and the waste is not being detoxified. At the same time, poisonous fumes, like

dioxins, are being emitted into the atmosphere through the chimneys of these incinerators,

which only adds to the plight of people of Pakistan.

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Incinerators, when operating properly burn at extremely high temperatures - in access of

1100 degrees Celsius, thereby only emitting carbon dioxide and water vapor into the

atmosphere. Conversely, the incinerators in Pakistan also emit a lot of smokea direct

indicator of low temperature burning and pose a direct threat to human life. Therefore, it

is essential to address the technology of incineration and the management aspect of it in

Pakistan. Whereas, the very same technology has been a success and is widely used in

the developed countries, where landfills are now discouraged due to the scarcity of

barren lands. Pakistan's case is not all that different. We have an agro-based economyand our land is extremely precious to waste it on dumpsites, which would ultimately

contaminate our other scarce commodity - water!!

The chimneys of incinerators should only emit carbon dioxide and water, and planting

more trees - nature's filtering agents - may solve this rise in 'green house' gases

Furthermore, the heat generated from incinerators may be used to produce steam, whichin turn could be used to drive turbines and generate electricity and at least supply a small

community with the much-needed resource to enhance development. In a country like

Pakistan where such resources are scarce, large-scale industrial incinerators could help

address the use of renewable energy and help in solving the crisis besieged in the rural

areas. Such endeavors have been successfully implemented throughout the developed

world.

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Anaerobic Digestion

Anaerobic digestion is a biological process in which organic

material is broken down by the action of microorganisms.Unlike composting, the process takes place in the absence of

air. The residue remaining after digestion can be used as a

soil conditioner and the process generates a gas, which can

be used as a fuel for domestic or industrial use. The

anaerobic digestion process is very similar to anaerobic

breakdown of organic waste in landfill sites but under

controlled conditions. Friends of the Earth supportsanaerobic digestion for sorted organic waste.

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Gasification

Gasification is where carbon based wastes are heated in the

presence of air or steam to produce fuel-rich gases. Thetechnology is based on the reforming process to produce

town gas from coal, and requires industrial scale facilities.

From the end of 1998, the dumping of sewage sludge at sea

has been prohibited. Friends of the Earth opposes

gasification for the 80% of municipal solid waste that can

be recycled or composted because it wastes valuable

resources, contributes to climate change and provides veryfew jobs.

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Pyrolysis

In this treatment, carbon based wastes are heated in the

absence of air to produce a mixture of gaseous and liquidfuels and a solid inert residue (mainly carbon). Pyrolysis

generally requires a consistent waste stream such as tyres or

plastics to produce a usable fuel product. Currently, there is

only one facility established in the UKtaking in tyres .

This has been shut because of operational problems. Friends

of the Earth opposes pyrolysis for the 80% of municipal

solid waste that can be recycled or composted for the samereasons that it opposes gasification.

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