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WASTE MINIMIZATION TECHNIQUES

PRESENTED BYABUZER ANSARIM.Sc. (F) ROLL NO. 36INSTITUTE OF ENVIRONMENTAL SCIENCE KURUKSHETRA UNIVERSITY

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Contents• WHAT IS WASTE ?• KINDS OF WASTE• THE 5 R’s OF WASTE MANAGEMENT• TREATMENT AND DISPOSAL OF WASTE• WASTE MINIMIZATION• WASTE REDUCTION TECHNIQUES• CONCLUSION• REFERENCES

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WHAT IS WASTE ?

• Waste is the unwanted or useless solid materials generated from combined residential, industrial and commercial activities in a given area

• It may be categorized according to its origin (domestic, industrial, commercial, construction or institutional)

•According to its contents (organic material, glass, metal, plastic paper etc); •According to hazard potential (toxic, non-toxin, flammable, radioactive, infectious etc).

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Kinds of Wastes

Solid wastes: wastes in solid forms, domestic, commercial and industrial 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.

Bio-degradable :can be degraded (paper, wood, fruits and others)Non-biodegradable :cannot be degraded (plastics, bottles, old machines, cans,

Styrofoam containers and others)Hazardous wastes: Substances unsafe to use commercially, industrially, agriculturally, or economically and have any of the following properties- ignitability, corrosivity, reactivity & toxicity.Non-hazardous : Substances safe to use commercially, industrially, agriculturally, or economically and do not have any of those properties mentioned above. These substances usually create disposal problems.

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The 5 R’s of Waste Management

• 1. REDUCE!• 2. REUSE!• 3. RECYCLE!• 4. REPAIR!• 5. REFUSE!

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Treatment and disposal of wasteSeveral methods are used for treatment and disposal. These are:

1. Composting 2. Incineration3. Landfilling4. Pyrolysis5. Recycling

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Treatment and disposal of wasteSeveral methods are used for treatment and disposal. These

are:1.Composting

- composting by trenching-open windrow composting-mechanical composting

2.Incineration3.Landfilling4.Pyrolysis5.Recycling

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1.Composting

It is a process in which organic matter of solid waste is decomposed and converted to humus and mineral compounds.

Compost is the end product of composting, which used as fertilizer.

Three methods of composting: (a) composting by trenching

(b) open windrow composting(c) mechanical composting

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Composting by trenchingTrenches 3 - 12 m long, 2 – 3 m wide and

1- 2 m deep with spacing 2 m.Dry wastes are filled up in 15 cm. On top

of each layer 5 cm thick sandwiching layer of animal dung is sprayed in semi liquid form.

Biological action starts in 2- 3 days and decomposition starts.

Solid waste stabilize in 4- 6 months and changed into brown colored odorless powdery form known as humus.

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Open windrow composting Large materials like broken glass, stone,

plastic articles are removed. Remaining solid wastes is dumped on ground

in form of piles of 0.6 – 1 m height. The width and length of piles are kept 1- 2 m

and 6 m respectively. Moisture content maintained at 60%. Temp. increases in side pile. After pile for turned for cooling and aeration

to avoid anaerobic decomposition. The complete process may take 4- 6 week.

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Mechanical compostingIt requires small area compare to

trenching and open windrow composting.

The stabilization of waste takes 3- 6 days.

The operation involved are reception of refusesegregationshreddingstabilizationmarketing the humus

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2.Incineration Incineration is a waste treatment process that involves

the combustion of organic substances contained in waste materials. 

Incineration and other high temperature waste treatment systems are described as "thermal treatment".

Incineration of waste materials converts the waste into ash, flue gas, and heat.

Incinerators are used for this process. Important points regarding incineration

Supplying of solid waste should be continuous.Waste should be proper mixed with fuel for complete combustion.Temp. should not less than 670 ˚C.

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Advantages Most hygienic method. Complete destruction of pathogens. No odor trouble. Heat generated may be used for steam power. Clinkers produced may be used for road construction. Less space required. Adverse weather condition has no effect.DisadvantagesLarge initial expense.Care and attention required otherwise incomplete combustion will increase air pollution.Residues required to be disposed which require money.Large no of vehicles required for transportation.

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3.Landfilling A landfill site is a site for the disposal of waste materials by

burial and is the oldest form of waste treatment. Historically, landfills have been the most common methods of

organized waste disposal and remain so in many places around the world.

The dumping is done with layers of 1- 2 m. The layer is covered with soil of 20 cm thickness.

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Advantages Simple method. No costly plant required. No residues or by products need to be disposed. Separation not required. Unused land can be used. Methane gas can be used ass fuel.

Disadvantages Large land required. Proper dumping site may not be available. Odor problem. Use of insecticides required. Leachate should be collected regularly. Methane gas should be collected properly. Green house gas problem.

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LAND REQUIRED FOR DISPOSAL OF MSW EMMISION OF METHANE FROM LANDFILL

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4.Pyrolysis Heating of the solid waste at very

high temp. in absence of air. Carried out at temp. between 500 ˚C

– 1000 ˚C.Gas, liquid and chars are the by

products.

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5.Recycling Recycling is processing used materials into

new products . It reduce the consumption of fresh raw

materials, reduce energy usage, reduce air pollution (from incineration) and water pollution (from landfilling).

Recycling is a key component of modern waste reduction and is the third component of the "Reduce, Reuse, Recycle" waste hierarchy.

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Recyclable materials include many kinds of glass, paper, metal, plastic, textiles, and electronics.

Although similar in effect, the composting or other reuse of biodegradable waste – such as food or garden waste – is not typically considered recycling.

Materials to be recycled are either brought to a collection centre or picked up from the curbside, then sorted, cleaned, and reprocessed into new materials.

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Biological reprocessing• Waste materials that are organic in nature, such as plant material, food

scraps, and paper products, can be recycled using biological composting and digestion processes to decompose the organic matter. The resulting organic material is then recycled as mulch or compost for agricultural or landscaping purposes. In addition, waste gas from the process (such as methane) can be captured and used for generating electricity. The intention of biological processing in waste management is to control and accelerate the natural process of decomposition of organic matter.

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WASTE MINIMIZATION

• Reasons of waste minimization:

1. Energy requirement- rises exponentially with increasing waste

2. Reduce total cost- for collection, segregation, intermediate storage, transport, treatment and final storage

3. Profitability - waste = inefficiency- reduce waste = efficiency & profitability

The act of reducing something to the least possible amount or degree or position.

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WASTE REDUCTION TECHNIQUES

4 major categories:

1. Inventory management2. Production process modification3. Volume reduction4. Recovery

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i) Inventory managementInventory management is divided into two:• inventory control• materials controlInventory Control • Involves techniques to reduce inventory size and hazardous chemical use while increasing inventory turnover.• proper inventory control help reduce wastes• method that can be used are purchasing in small quantities, purchasing in appropriate container sizes and just-in-time purchasing

Materials Control• Proper control over the storage of raw materials, products and process waste and the transfer of these items within the process and around the facility.• Minimize the losses through spills, leaks or contamination• Ensure the material is efficiently handled and used in the production process and does not become waste

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ii) Production process modification

3 techniques for production process modification:a) operation and maintenance proceduresb) material changec) equipment modifications

a) operation and maintenance procedures- corrective and preventive maintenance can reduce waste generation

caused by equipment failure.- can help spot potential sources of release and correct a problem before

any material is lost.

b) material change

-the replacement of materials used in either a product formulation or in a production process, can either result in elimination of a hazardous waste or facilitate recovery of a material.-Example: In pharmaceutical company – replace solvent based tablet coating process with a water based process

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c) equipment modifications

- installation of more efficient equipment or modification of equipment can reduce the generation of waste.

- installation of completely new equipment may be involved.

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iii) Volume reductiona) source segregationb) concentration

a) Source segregation- segregation of wastes allows them to be more readily removed or recovered.

b) Concentration- concentrate waste through separation processes

such as filtration, centrifugation, membrane separations and evaporations

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iv) Recovery- on-site- off-site

On-site Recovery- reduce possible handling losses and allow the management

of the waste to remain within the compass of the producer.- Recovered material can be reused as raw material- Example: in printing industry, use vapor recovery system to

recover solvents

Off-site Recovery- if on-site recovery is not feasible, for economic or other

reasons, off-site recovery should be considered.- Waste may be transferred to other company for use as a raw

material in the other company’s manufacturing process.

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CONCLUSION:

• It is found that with increase in the global population and the rising demand for food and other essentials, there has been a rise in the amount of waste being generated daily by each household. Waste that is not properly managed, especially excreta and other liquid and solid waste from households and the community, are a serious health hazard and lead to the spread of infectious diseases.

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References• www.atsdr.cdc.gov• www.indiatogether.org/2004/apr/env-rethink.htm.• http://www.epa.gov/epawaste/nonhaz/index.htm• http://www.epa.gov/epawaste/conserve/index.htm

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Thank u …