1)solid waste disposal and management

7/30/2019 1)Solid Waste Disposal and Management

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SOLID WASTE DISPOSALAND MANAGEMENT


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Urbanisation

People livingin urban areasin the World -

1985 41%

2015 60%

Of the urbanpopulation68% will beliving incities of lowincome andlower middleincomecountries


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Environmental Pollution Disposal of Wastes A major

problem faced in all towns and

cities Consequence Grave public health

risk

Need of the hour

Proper wastedisposal using scientific means andappropriate technology


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Terminology Solid Waste dry refuse wastes

which are solid

Includes House refuse vegetable and animal waste,

ashes, rubbish, debris etc

Trade refuse from factories, business and

commercial centres, slaughter houses etc Street refuse - empty packets, bottles, tree

leaves and street sweepings etc


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Terminology Consists of

Garbage All sorts of putrescible organic wastes Ashes incombustible waste products

Rubbish Non putrescible wastes excluding ashes Dust

Made up of both organic or combustiblematter and inorganic or mineral or noncombustible matter

Quantity and composition of refuse variesfrom place to place and from season to season Depends on the type of town, standard of

living of the people, habits etc Average Indian Town 0.4 to 0.5 kg/

capita/day


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Sources of Solid Wastes Domestic or Residential Food, Paper,

Packaging Materials, Glass, Metal, Ash, HazardousMaterials Like Batteries etc

Commercial(Shops, Hotels, Markets, Offices etc) Food, Paper, Packaging Materials, Glass, Metal, Ash,Hazardous Materials

Industrial Metals, Plastics, Oils, Process Wastes,Hazardous Wastes

Construction Soil, Concrete, Wood, Steel,Plastics, Glass


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Municipal Solid Waste Refuse from households, non-

hazardous solid wastes from

industrial, institutional, andcommercial establishments (includinghospitals), market waste, yard waste,and street sweepings


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Municipal Solid Waste

Generation and Composition


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Municipal Solid Waste

Generation


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Municipal Refuse

Generation


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Percapita MSW Generation in the USA

1.6kg/person/day


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MSW Generation Rates


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Composition of MSW


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MSW Composition - Delhi


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MSW Composition - Madras


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Biodegradable vs Non-biodegradable Wastes in MSW


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MSW Disposal andManagement

Includes collection, transfer, treatment,recycling, resource recovery, anddisposal of MSW

Actors and Partners Households, Communities, and Other

Service Users NGOs

Local Self Government State Governments Private Sector Enterprises External Aid Agencies


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Calicut City

Area - 82.67 sq. km.

Population 4,36,527 (2001 census)

Houses 70,000

Wards 51

Flats

100Activity Predominantly Residential


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MSW in Calicut City

Quantity - 350 tonnes/day

Per capita Generation- 800g/day

Main source - Households

Other sources - Markets, Hospitals,Commercial Establishments

Vegetable markets - 40-50 t/day

Construction - 20 t/day


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MSW in Calicut City

Biodegradable Wastes - 70%

Recyclable Wastes - 15%

Inert - 10-15%

Others - 0-5%

Calorific Value - 800 to 1100 Kcal/kg Moisture Content - 55%

C:N Ratio - 40


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Prevalent Practices and Deficiencies in

SWM Schemes in Developing Countries

No segregation at source

No system for primary collection of solid wastes. Wasteis thrown all round. Uncontrolled littering NIMBYsyndrome

Temporary storage in open bins very unhygienic waste is littered all round the bin

Bins are not regularly cleared

Dumping of solid wastes in drains blockage, mosquitobreeding

Throwing wastes into water bodies

Wastes from markets and slaughter houses are notproperly disposed of

Open burning of wastes


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Prevalent Practices and Deficiencies inSWM Schemes in Developing Countries

Mixing infectious wastes from hospitals and hazardouswastes with municipal solid wastes

Rats and flies breed in waste dumps Spread of diseases and outbreak of epidemics Leachate from dumps pollute groundwater Plastic wastes Construction/ demolition wastes Street sweeping timing, methods, tools inadequate Transportation system grossly inadequate

Collection schedule is not notified Processing and treatment of waste unscientific. Pre

and post processing rejects dumped at the disposal siteitself


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Prevalent Practices and Deficiencies inSWM Schemes in Developing Countries

Financial management is very poor

Landfills are rather dumps

No community participation No system for monitoring

Provisions of the legislation are not compliedwith

Inadequately trained staff


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What is Required

Rehabilitation and modernisation ofexisting systems

Creating public awareness on theimportance of maintaining thesurroundings neat and its closeinterrelation with public health

Enhancing the sense of responsibility and

capacity of the local people and personnelof the local bodies

Implementing a system that it financiallyand technologically feasible and socially

acceptable


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A Good MSW Disposal System

Segregated handling and storage of wastes atthe source

House to house collection of wastes Transferring the wastes to the transfer

station or community bins

Secondary collection and transport to thedisposal sites

Recycling and reusing whatever is possible


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Source Separation in the Kitchen


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Bins for Separation at Source

Municipal Solid Wastes Biodegradable Non biodegradable

Recyclable Hazardous Others

Green - Biodegradable

White - Recyclable Red - Domestic Hazardous Black - Others


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Five Phases of MSWCollection


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Collection Vehicles with CanSnatchers


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Disposal of Refuse

Open burning

Dumping into the sea

Sanitary Landfills

Incineration

Composting

Ploughing in fields

Hog feeding

Grinding and discharging into sewers

Salvaging

Fermentation and biological digestion


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Open burning

Not an ideal method in the presentday context


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Dumping into Sea

Possible only in coastal cities

Refuse shall be taken in barges

sufficiently far away from the coast(15-30 km) and dumped there

Very costly

Not environment friendly


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Sanitary Landfilling

Simple, cheap, and effective

A deep trench (3 to 5 m) is excavated

Refuse is laid in layers Layers are compacted with some

mechanical equipment and covered withearth, levelled, and compacted

With time, the fill would settle Microorganisms act on the organic

matter and degrade them


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Decomposition is similar to that incomposting

Facultative bacteria hydrolyze complexorganic matter into simpler water solubleorganics

These diffuse through the soil where fungiand other bacteria convert them to carbon

dioxide and water under aerobic conditions Aerobic methanogenic bacteria utilize the

methane generated and the rest diffusesinto the atmosphere


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Too much refuse shall not be buried firehazard

Moisture content not less than 60% for good

biodegradation Refuse depth more than 3m danger of

combustion due to compression of bottomlayers hence should be avoided

Refuse depth is generally limited to 2m

Temperature in the initial stages ofdecomposition as high as 70 degree C then drops

Reclaimed areas may be used for other uses


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Engineered Landfills

Bottom of the trench is lined withimpervious material to prevent the

leachate from contaminatinggroundwaters

A well designed and laid out leachatecollection mechanism is to be provided

Leachate so collected is treated andthen disposed of


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.A Typical Sanitary Landfill


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A Typical Sanitary Landfill


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Components of a TypicalLandfill


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MSW Landfill Gas


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Incineration

A method suited for combustiblerefuse

Refuse is burnt Suited in crowded cities where sites

for land filling are not available

High construction and operationcosts

Sometimes used to reduce the

volume of solid wastes for land filling


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Incineration

Primary chamber designed tofacilitate rapid descication of moistrefuse and complete combustion of

refuse and volatile gases A ledge or drying hearth is provided for

this purpose Secondary chamber between the

primary chamber and the stacktemperatures above 700 degree C

All unburnt and semiburnt material arecompletely burnt here

An Incinerator


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An Incinerator


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Waste to Energy Combustors

Incinerators Refuse was burnedwithout recovering energy exhaust

gas is very hot

exceeds theacceptable inlet temperature forelectrostatic precipitators used forparticulate emission control

Modern combustors combine solidwaste combustion with energy recovery


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Combustors

Storage pit for storing and sortingincoming refuse

Crane for charging the combustion box

Combustion chamber consisting of bottomgrates on which combustion occurs

Grates on which refuse moves

Heat recovery system of pipes in whichwater is turned to steam

Ash handling systems

Air pollution control systems


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Combustors

Grates Provide turbulence so that theMSW can be thoroughly burned, moves

the refuse down, provides underfire airto the refuse through openings in it (toassist in combustion as well as to coolthe grates)

Operating temperature of combustors ~980 to 1090 degree C


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A Typical MSW Combustor


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A Typical MSW Combustor

Grates


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Grates


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Grates


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Composting

Similar to sanitary landfilling Yields a stable end product good soil

conditioner and may be used as a base

for fertilizers Popular in developing countries Decomposable organic matter is

separated and composted Methods

Open window composting Mechanical composting


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Composting

Open window composting Refuse is placed in piles, about 1.5m high and 2.5m

wide at about 60% moisture content Heat build up in the refuse piles due to biological

activity temperature rises to about 70 degree C Pile is turned up for cooling and aeration to avoid

anaerobic conditions Moisture content is adjusted to about 60% Piled again temperature rises to about 70 degree C The above operations are repeated After a few days (~ 7 to 10 weeks) temperature

drops to atmospheric temperature indication ofstabilisation of compost


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Composting

Mechanical composting

Process of stabilisation is expedited

by mechanical devices of turning thecompost

Compost is stabilised in about 1 to 2weeks


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Composting

Methods used in India

Indore method aerobic brick pits 3 x 3 x 1 m upto 8-12 weeks materials are turned regularly inthe pits and then kept on ground for about 4-6weeks 6 to 8 turnings in total

Bangalore method anaerobic earthen trenches10 x 1.5 x 1.5 m left for decomposition takes 4

to 5 months


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Vermicomposting

Ideal for biodegradable wastes fromkitchens, hotels etc

At household level, a vessel or tray

more than 45 cm deep, and 1 x 0.60mmay be sufficient

A hole shall be provided at one end inthe bottom for draining the leachate out

into a tray or vessel Lay a 1 thick layer of baby metal or

gravel at the bottom of the tray


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Vermicomposting

Above that lay an old gunny bag ora piece of thick cloth, a layer of

coconut husk upside down over itand above that a 2 thick layer ofdry leaves and dry cow dung

(powdered) Lay the biodegradable waste over

it


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Vermicomposting

Introduce good quality earthwormsinto it (~ 10 g for 0.6 x 0.45 x

0.45 m box) If the waste is dry, sprinkle water

over it daily

Rainwater should not fall into thetray or vessel or box

Keep it closed


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Vermicomposting

If the box is kept under bright sunearthworms will go down and compost

can be taken from the top Compost can be dried and stored

Continue putting waste into the box

Add little cow dung at intervals

Do not use vermiwash directly. Dilute inthe ratio 1:10 before use


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Disposal by ploughing into fields

Not very commonly used

Not environment friendly in

general


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Disposal by hog feeding

Garbage is fed to animals like hog,swines etc

Raw feeding may lead to diseases inthese animals

Hence garbage may be heated upto 100degree C as a precaution before feeding

to kill disease causing bacteria

Not very popular


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Grinding and discharging intosewers

Not common in India

Refuse is ground well in grinders

and then fed into sewers Disposal of garbage into sewers

BOD and TSS increases by 20-30%

Disposal of residual refuse still aproblem


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Salvaging

Materials like paper, metal, glass,rags, certain types of plastic etc

can be salvaged, recycled, andreused


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Fermentation or BiologicalDigestion

Garbage is placed in air tight sealedtanks for about 10 days and then in the

presence of air for about 15-20 days Digested refuse a good soil

conditioner

Leachate from the tank may be

recirculated for keeping the garbagewet for proper digestion


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Future Strategy

Biodegradable Waste convert tocompost

Recycle whatever is possible Hazardous wastes dispose it by

suitable methods

Landfill or incinerate the rest


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The Key to SWM

The Three RsReduce

Refuse

Recycle

1)solid waste disposal and management

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