WASTE MANAGEMENT TECHNIQUES

Presented by : Charan VadlapatiB.Tech (II year)

What is Waste?

A material, substance, or by-product which is eliminated or discarded as no longer useful or required after the completion of a process.

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TYPES OF WASTES

Solid wastes: Domestic , commercial and industrial wastes especially common as co-disposal of wastes

Examples: Plastics, bottles, cans, papers, scrap

iron, and other trash

Liquid Wastes: wastes in liquid form

Examples: Domestic washings, chemicals, oils, waste water from ponds, manufacturing industries and other sources

Types of Solid Wastes

Domestic & Commercial Waste Industrial waste

Bio-medical waste

Types of Liquid Wastes

Polluted water body Household Waste Water

Industrial Waste Water

MSW principally includes:Domestic Waste: Kitchen waste, plastic, wood, rag/cloth and any other household garbage, Street sweeping waste, Construction and demolition debris and Sanitation residues.

About 46 million ton of MSW is generated annually (as per census 2001) Approx. 30,000 tones/day is generated by 23 Metro Cities in India 50,000 Tones/day are generated by Class I cities(5,00,000/- 7000 Tones of plastics waste is generated every day

Municipal Solid Waste in India:

MSWM in India is driven by Municipal Solid Waste (Management & Handling) Rule, 2000 which envisages segregated storage of waste at source, collection from source, protected transportation to the treatment facility, establishment environmentally safe treatment system and its operation and maintenance and safe disposal of inert rejects.

Rules are under revision and CPHEEO is also preparing revised Manual on MSWM for urban local bodies in India

Municipal Solid Waste in India:

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SOURCES OF MUNICIPAL SOLID WASTES

Households

Commerce

Composition of MSW in a Typical Indian City

Source: CPHEEO Manual on MSW, 2005

Total Organic Fraction - 40%, Combustible Fraction - 37%, Recyclables - 8%, Inert - 15%

Garbage Rubbish

Refuse

Trash

COLLECTION OF MUNICIPAL SOLID WASTE

DOOR-TO-DOOR COLLECTION

COMMUNITY BINS

How the Waste is Managed...?

Segregation at Source

Segregation at Transit station

Biodegradable Waste

Non Biodegradable wasteRecyclable

Toxic waste

Transportation

Dumping Yard

OPTIONS FOR SUSTAINABLE WASTE MANAGEMENT

Composting Vermicomposting Open Windrows Composting Closed Vessel Composting

Energy Recovery/Power Generation Bio-methanization Refused Derived Fuel Plasma Vitrification Incineration Pyrolysis

VERMICOMPOSTING:

COMPOSTING

Open windrows composting:

Process: Composting is done through windrow composting method for 30 to 40 days. very popular, cheaper and Practiced in many Indian city as one of the traditional method.

Limitations: Out of total mixed MSW only 10 to 15 % is converted into compost, vvery high land requirements and 40 to 50 days of operation cycle. Maximum part of waste goes t landfilling as rejects are more

CLOSED VESSEL COMPOSTING

Generally describes a group of methods that which confine

the composting materials within a building, container, or vessel.

Closed vessel composting systems can consist of metal or concrete bunkers in

which air flow and temperature can be controlled, using the principles of a

"bioreactor".

Generally the air circulation is metered in via buried tubes that allow fresh air to be

injected under pressure, with the exhaust being extracted through a bio filter, with

temperature and moisture conditions monitored using probes in the mass to allow

maintenance of optimum aerobic decomposition conditions.

1st week of composting chamber

2st week of composting chamber

CLOSED VESSEL COMPOSTING

BIOMETHANIZATION/BIOGAS:

Well known technology for domestic sewage and organic wastes treatment, but not for mixed MSW.

Biological conversion of biodegradable organic materials in the absence of oxygen at temperatures 55 to 75oC.

Residue is stabilized organic matter that can be used as soil amendment after proper dewatering.

Digestion is used primarily to reduce quantity of sludge for disposal / reuse.

Methane gas generated used for electricity / energy generation or flared.

The process of conversion of garbage into fuel pellets involves primarily drying, separation of combustibles from garbage, size reduction and pelletization after mixing with binder and additives as required.

The reduction in moisture is very crucial and can be done artificially or by natural sun drying. Sun drying is preferred when adequate land is readily available. However, during periods of heavy rainfall, alternate arrangements for drying will have to be made.

Many plants in Indian cities e. Hyderabad, Kochi, Nashik etc. funded under JnNURM but most of them are not working due to various reasons.

Considerable energy inputs required for moisture reductions, shredding, segregation and pelletization and which is not economical.

If properly designed and segregation achieved at source can be very economical and suitable for industrial use

REFUSE DERIVED FUEL (RDF):

This is an emerging technology for energy/resources recovery from organic wastes. The system basically uses a Plasma Reactor which houses one or more Plasma Arc Torches.

A high voltage discharge and consequently an extremely high temperature environment (above 3000 degree Celsius).

Non-commercial has been proven technically (pilot scale) but not commercial scale / financially in India.

Organic materials are converted to syngas composed of H2, CO. Inorganic materials are converted to solid slag. Syngas can be utilized for energy production or proportions can be

condensed to produce oils and waxes. Very less land required, landfilling is also minimum.

Plasma Arc Technology/Plasma Pyrolysis Vitrification (PPV):

Plasma Arc Technology/Plasma Pyrolysis Vitrification (PPV):

Combustion of raw MSW, moisture less than 50%, Sufficient amount of oxygen is required to fully oxidize the fuel

Combustion temperatures are in excess of 850oC Waste is converted into CO2 and water concern about toxics (dioxin,

furans) Any non-combustible materials (inorganic such as metals, glass) remain

as a solid, known as bottom ash (used as feedstock in cement and brick manufacturing)

Fly ash APC (air pollution control residue) particulates, etc Needs high calorific value waste to keep combustion process going,

otherwise requires high energy for maintaining high temperatures Combined technologies available for power generation Not on commercial scale in India, some projects are in pipeline..

Incineration:

Typical Incineration Flow chart

Pyrolysis involves an irreversible chemical change brought about by the action of heat in atmosphere devoid of oxygen. Synonymous terms are thermal decomposition, destructive distillation and carbonization.

Pyrolysis is carried out at temperature between 500 and 1000OC to produce three component streams.

Byproducts from pyrolysis are char, liquids and gas have a large calorific value.

Certain amount of excess heat still remains which can be commercially exploited.

Many international and national companies are interested but successful model is not available in country.

PYROLYSIS:

LAND FILLS

Source: http://www.epa.gov/garbage/dmg2/chapter9.pdf

SANITARY LANDFILL (AKA MUNICIPAL SOLID WASTE LANDFILL)

SANITARY LANDFILLS (ACCOMMODATE 57% OF TOTAL MUNICIPAL SOLID WASTE):

Each day trash is spread in thin layers

Compacted down Covered with a soil

layer Graded for drainage

http://www.epa.gov/garbage/dmg2/chapter9.pdf

Sanitary landfills have largely replaced open dumps.

PROBLEMS WITH LANDFILLS…

Landfills require space Produce methane gas (can be used for energy, or can cause climate

change) Leachate must be collected and treated Potential for water pollution NOT a long-term remedy

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