ENVIRONMENTAL ENGINEERING-IIUnit- V

L-47

SOLID WASTE MANAGEMENT

PART-I

Common scenario in Indian cities

Solid Waste

1. INTRODUCTIONDefinition:-

‘Solid wastes are all the wastes arising from human and animal activities that are normally solid and that are discarded as useless or unwanted’

* Solid waste may consist of organic and inorganic waste materials such as product packaging, grass clippings, furniture, clothing, bottles, kitchen refuse, paper, appliances, paint cans, batteries etc

Composition of Solid waste in India

The composition of municipal waste varies greatly from country to country and changes significantly with time.

Life cycle of solid waste

Waste management hierarchy

Impacts of solid waste on human health

Chemical poisoning through chemical inhalation of toxic gases emitted from solid wastes

Uncollected waste can obstruct the storm water runoff resulting in local area flooding

Low birth weight Cancer Congenital malformations (Related to eyes) Neurological disease (Related to brain) Odour pollution

Nausea and vomiting because of foul smell.

Increase in hospitalization of diabetic residents living near solid waste disposal sites.

Mercury toxicity from eating fish with high levels of mercury.

Problem of flies, mosquitoes, rodents (rats etc) and related diseases (Malaria, plague etc.)

Impacts of solid waste on Environment.

Waste breaks down in landfills to form methane, a potent greenhouse gas

Change in climate and destruction of ozone layer due to waste biodegradable

Visual pollution, unpleasant sights Leaching: is a process by which solid

waste enter soil and ground water and contaminating them.

2. CLASSIFICATION OF SOLID WASTE

A] Source based

1) Residential

2) Commercial

3) Institutional

4) Municipal

5) Industrial

6) Agricultural

B] Type based classification1. Garbage:- Results from handling, sale,

storage, preparation, cooking and serving of food. Comprises of putresceble organic matter. Needs special attention in handling, storage and disposal

2. Ashes and residues:- remaining from burning of combustible materials.

3. Combustible and non combustible:- paper, wood, rubber etc are combustible materials while metals, glass etc are non combustible wastes

4. Bulky wastes:- out of service Refrigerators, ACs, Furniture are catagorised under bulky waste

5. Street wastes:- wastes resulting from different street activities such as cleaning, sweeping etc. Examples are paper, plastic, garden wastes

6. Bio-degradable and non biodegradable:Wastes capable of organic decomposition are

biodegradable wastes. Examples:- food waste Wastes not capable of organic decomposition are

non biodegradable wastes. Examples:- Ferrous metals, glass etc

7. Dead animals:- Dead bodies of animals such as rats, dogs, cats etc.

8. Abandoned vehicles:- Large abandoned vehicle after their utility. Cars, Vans etc

9. Construction and demolition waste:- Waste resulting from construction and demolition activities.

10. Farm wastes:- Waste resulting from farm yard activities. Agro waste

11. Hazardous wastes:- Wastes capable of posing danger to human health. Examples:- DDT, Petroleum waste

12. Sewage wastes:- Results from sedimentation and digester tanks of waste water plant

3. Sources of Solid wastesSolid wastes come from a variety of sources

including: Residential Commercial Institutional Construction and Demolition Municipal Services Treatment Plant Sites Industrial Agricultural

Source

Typical facilities, activities or locations

Types of solid wastes

Residential

homes, flats, apartment blocks, chawls , slums etc

food wastes, paper, cardboard, plastics, textiles, yard wastes, wood, glass, metals, special wastes (e.g. bulky items such as heavy goods, batteries, oil, tyres), household hazardous wastes

Commercial

Shops, restaurants, markets, office buildings, hotels, motels, print shops, service stations, auto repair shops etc

Paper, cardboard, plastics, wood, metals, food wastes, glass, special wastes (as above), hazardous wastes

Institutional

Schools, hospitals, universities, prisons, government centres etc

As above in commercial

Construction and demolition

New construction sites, road repairs, building demolition

Wood, steel, concrete, dirt etc

Municipal services (excluding treatment works)

Street cleaning, landscaping, parks and beaches, creek bed cleaning, litter bins

Special wastes, rubbish, litter, sweepings, debris, general wastes

Treatment plant sites

Water, wastewater, industrial treatment processes etc

Effluent plus residual sludges

Municipal solid waste (MSW)

All of the above All of the above

Industrial

Construction, fabrication, light and heavy manufacturing, refineries, chemical plants, power stations, demolition etc

Industrial process wastes, scrap materials etc. Non-industrial wastes including food wastes, rubbish, ashes, demolition and construction wastes, special wastes, hazardous wastes

Agricultural

Crops, dairies, feedlots, piggeries, farms etc

Spoiled food wastes, agricultural wastes, rubbish, hazardous wastes

Factors affecting generation of Solid waste

1. Geographic location

2. Seasons

3. Collection frequency

4. Population diversity

5. Extent of recycling and salvaging

6. Public attitude

7. Legislation

DEGRADATION PERIOD OF SOME SOLID WASTES

The type of litter we generate and the approximate time it takes to degenerate

Type of litter Approximate time it takes to degenerate the litter

Organic waste such as vegetable and fruit peels, leftover foodstuff, etc.

a week or two.

Paper 10–30 days

Cotton cloth 2–5 months

Wood 10–15 years

Woolen items 1 year

Tin, aluminium, and other metal items such as cans

100–500 years

Plastic bags one million years?

Glass bottles undetermined

PHYSICAL PROPERTIES OF SOLID WASTE

4.Physical Properties of solid wastes

1. Density This is the weight per

unit volume and is expressed as kg/m3

Critical factor in design of landfills

Inert waste such as construction and demolition waste may have higher density.

COMPONENT DENSITY(kg/m3)

Food wastes 288

Paper 81.7

Plastics 64

Garden trimmings

104

Glass 194

Ferrous metals

320

Procedure for finding out density of solid waste

1. Cubical container of 60 cm x 60 cm x 60 cm (or any known volume) is taken and empty wt is recorded.

2. Solid waste is filled to overflow in the cubical container.

3. Compaction is done by tamping the container thrice.

4. For compaction container is lifted up 6cm above the ground and dropping down squarely.

5. The top of container is leveled with the help of a straight edge.

6. Finally container is weighed.

Density = (Wt of container filled with solid waste – empty wt of

container) / volume of container

2.Moisture Content•The ratio of the weight of water to the total weight of the wet waste.•Moisture increases weight of solid wastes•Plays important role in incineration.•Wastes should be protected from rain and other water.

M=[(w-w1)/w]x100M=Moisture contentw1=weight of sample after drying at 1050 Cw= initial weight of sampleAbove table shows moisture content of some common wastes

Type of WasteMoisture ContentRange (%)

Moisture ContentTypical (%)

RESIDENTIAL

Food wastes (mixed) 50 - 80 70

Paper 4 - 10 6

Plastics 1 - 4 2

Yard Wastes 30 - 80 60

Glass 1 - 4 2

COMMERCIAL

Food wastes 50 - 80 70

Rubbish (mixed) 10 - 25 15

CONSTRUCTION & DEMOLITION

Mixed demolition combustibles

4 - 15 8

Mixed construction combustibles

4 - 15 8

INDUSTRIAL

Chemical sludge (wet) 75 - 99 80

Sawdust 10 - 40 20

Wood (mixed) 30 - 60 35

AGRICULTURAL

Mixed Agricultural waste 40 - 80 50

Manure (wet) 75 - 96 94

3. Particle Size and Distribution•Important for the recovery of materials. •Important for design of mechanical separatorsSc= l Sc= [(l+w)/2]Sc= [(l+w+h)/3]Sc= Size of componentl= Length in mmw= Width in mmh= Height in mm

4. Field Capacity•The field capacity of MSW is the total amount of moisture which can be retained in a waste sample subject to gravitational pull.•Field capacity of residential and commercial sources are in the range of 50 - 60%.

5. Permeability of Compacted Wastes•The hydraulic conductivity of compacted wastes is an important physical property because it governs the movement of liquids and gases in a landfill. •Permeability depends on the other properties of the solid material include pore size distribution, surface area and porosity.

CHEMICAL PROPERTIES OF SOLID WASTE

5. Chemical properties of solid wastes

1. Proximate AnalysisProximate analysis includes four tests –

1) Loss of moisture when heated to 105°C for 1 hour;

2) Volatile combustible matter (loss on ignition);

3) Fixed carbon; and

4) Ash (weight of residue after combustion).

TYPE OF WASTE

MOISTURE VOLATILES CARBON ASH

Mixed food 70.0 21.4 3.6 5.0

Mixed paper 10.2 75.9 8.4 5.4

Mixed plastics

0.2 95.8 2.0 2.0

Yard wastes 60.0 30.0 9.5 0.5

Glass 2.0 - - 96-99

Residential MSW

21.0 52.0 7.0 20.0

Typical Proximate Analysis Values (% by weight)

2. Fusing Point of Ash•This is the temperature at which the ash resulting from the burning of waste will form a solid (clinker) by fusion. •Typical fusing temperatures are from 1100 - 1200°C.

3.Elemental Analysis•This is also known as ultimate analysis and involves the determination of carbon, hydrogen, oxygen, nitrogen, Sulphur, and ash. • The results of this analysis is used to characterize the composition of the organic matter in wastes.• This is important for C/N ratios for biological decomposition.

4.Energy Content•The energy content of the components of waste can be determined using a boiler system, laboratory bomb calorimeter, or by calculation using elemental composition. •The SI unit of measurement is kJ/kg.

Objective Questions1. Pick out odd one

i. Paper, wood, cardboard, glass

ii. Paper, tree leaves, food waste, plastic

2. Paper waste requires _____ weeks to disintegrate.

3. Leftover Food items require _______ time to disintegrate.

4. In India ___ % of solid waste is biodegradable

Theory QuestionsQ1. Classify the solid wastes based on

a. Sources

b. Types

Q2. Write short notes on

1. Physical characteristics of solid waste

2. Chemical characteristics of solid wastes

Q3. Explain procedure for finding out density of solid waste.

END OF PART-I