SOLID WASTE AND ITS MANAGEMENT

 It is the collecting, treating, and disposing of solid material that

is discarded because it has served its purpose or is no longer
useful.
 Improper disposal of municipal solid waste can create
unsanitary conditions, which can lead to environment pollution
and to outbreaks of vector-borne diseases.
 Higher standards of living of ever increasing population has
resulted in an increase in the quantity and variety of waste
generated.
Therefore, management of solid wastes has become very important
in order to minimize their adverse affects on the environment.
 Sources/Classification of solid wastes
(i) Domestic/Residential Waste: waste generated as a consequence of
household activities such as cooking, cleaning, repairs, hobbies,
redecoration, empty containers, packaging, clothing, old books,
writing/new paper, and old furnishings.
(ii) Municipal Waste: Wastes resulting from municipal activities and services
such as street waste, dead animals, market waste and abandoned
vehicles.

(iii) Commercial Waste: solid wastes that originate in offices, wholesale and
retail stores, restaurants, hotels, markets, warehouses and other
commercial establishments.

(i) Institutional Waste: Institutional wastes are those arising from institutions
such as schools, universities, hospitals and research institutes.
(v) Garbage: Includes animal and vegetable wastes resulting from the handling,
storage, sale, preparation, cooking and serving of food. Such wastes contain
putrescible organic matter, which produces strong odours and therefore attracts rats,
flies. It requires immediate attention in its storage, handling and disposal.
(vi) Rubbish: It is a general term applied to solid wastes originating in households,
commercial establishments and institutions, excluding garbage and ashes.
(vii) Ashes: Ashes are the residues from the burning of wood, coal, charcoal, coke and
other combustible materials, for cooking and heating in houses, institutions and
small industrial establishments. When produced in large quantities at power
generating plants and factories these wastes are classified as industrial wastes.
Ashes consist of a fine powdery residue, cinders and clinker often mixed with small
pieces of metal and glass.
(viii) Bulky Wastes: Wastes which cannot be accommodated in the normal storage
containers of households. For this reason they require special collection. Examples
of bulky wastes are large household appliances such as cookers, refrigerators and
washing machines as well as furniture, crates, vehicle parts, tyres, wood, trees
and branches.
(ix) Street Sweeping: wastes that are collected from streets, walkways, alleys, parks and
vacant lots. It commonly takes place in developing countries, where littering of public
places is a far more widespread and acute problem. Mechanised street sweeping is
the dominant practice in the developed countries. Street wastes include paper,
cardboard, plastic, dirt, dust, leaves and other vegetable matter.
(x) Dead Animals: This is a term applied to dead animals that die naturally or
accidentally killed. This category does not include carcass and animal parts from
slaughterhouses which are regarded as industrial wastes.
(xi) Construction and Demolition Wastes: waste materials generated by the
construction, refurbishment, repair and demolition of houses, commercial buildings
and other structures. It mainly consists of earth, stones, concrete, bricks, lumber,
roofing materials, plumbing materials, heating systems and electrical wires and
parts of the general municipal waste stream, but when generated in large amounts at
building and demolition sites, it is generally removed by contractors for filling low
lying areas and by urban local bodies for disposal at landfills.
(xii) Industrial Wastes: Discarded solid materials of manufacturing processes and
industrial operations. They cover a vast range of substances which are unique to each
industry. For this reason they are considered separately from municipal wastes.
(xiii) Hazardous Wastes: Hazardous wastes may be defined as wastes of industrial,
institutional or consumer origin which, because of their physical, chemical or
biological characteristics are potentially dangerous to human and the environment. In
some cases although the active agents may be liquid or gaseous, they are classified as
solid wastes because they are confined in solid containers. Typical examples are:
solvents, paints and pesticides whose spent containers are frequently mixed with
municipal wastes and become part of the urban waste stream. Others, such as
pathological wastes from hospitals and radioactive wastes, require special
handling at all time.
(xiv) Sewage Wastes: The solid by-products of sewage treatment are classified as
sewage wastes. They are derived from the treatment of organic sludge from both the
raw and treated sewage. The inorganic fraction of raw sewage such as grit is
separated at the preliminary stage of treatment, but because it entrains putrescible
organic matter which may contain pathogens, must be buried/disposed off without
delay.
 Effects of solid waste
 Municipal solid wastes heap up on the roads due to improper disposal system.
 Dumping allows biodegradable materials to decompose under uncontrolled and
unhygienic conditions which produces foul smell and breeds various types
of insects and infectious organisms besides spoiling the aesthetics of the site.
 Industrial solid wastes contains toxic materials, which may spread on land and
can cause changes in physicochemical and biological characteristics
thereby affecting productivity of soils.
 Toxic substances may leach or percolate to contaminate the ground water.
 Various types of wastes like cans, pesticides, cleaning solvents, batteries
(zinc, lead or mercury), radioactive materials, plastics and e-waste are
mixed up with paper, scraps and other non-toxic materials which could be
recycled. Burning of some of these materials produces dioxins, furans and
polychlorinated biphenyls, which have the potential to cause various types of
ailments including cancer.
 Treatment and disposal methods

 The selection of the disposal method upon the type and source of
solid waste, as the composition of solid waste is not same
everywhere
 Most prominent solid waste disposal methods are :
1. Sanitary landfill
2. Incineration
3. Composting
4. Dumping
5. Recycling and reuse
 Sanitary landfills
 In a sanitary landfill, garbage is spread out in thin layers, compacted
and covered with clay or plastic foam. In the modern landfills the
bottom is covered with an impermeable liner, usually several layers of
clay, thick plastic and sand. The liner (impermeable material like plastic)
protects the ground water from being contaminated due to percolation of
leachate. Leachate from bottom is pumped and sent for treatment. When
landfill is full it is covered with clay, sand, gravel and top soil to
prevent seepage of water.
 Several wells are drilled near the landfill site to monitor if any leakage
is contaminating ground water.
 Methane produced by anaerobic decomposition is collected and burnt
to produce electricity or heat.
Adverse impacts may occur from landfill operations.
These impacts can vary:
i. Fatal accidents (e.g., scavengers buried under waste piles).
ii. Infrastructure damage (e.g., damage to access roads by heavy
vehicles).
iii. Pollution of the local environment (such as contamination of
groundwater and/or aquifers by leakage and residual soil contamination
during landfill usage, as well as after landfill closure).
iv. Off gassing of methane generated by decaying organic wastes
(methane is a greenhouse gas many times more potent than carbon
dioxide, and can itself be a danger to inhabitants of an area).
v. Harbouring of disease vectors such as rats and flies, particularly from
improperly operated landfills.
Components of a Typical Landfill
Problems
 Construction is costly
 Liners often develop cracks as it react with various chemicals
present in the waste
 Rate of decomposition is variable as less oxygen is available due
to tight compression of waste
Advantages
 Infectious diseases are minimized
 No air pollution from burning
 Minimal fire hazards
 Methane gas generated is sold as a fuel
 INCINERATION
 Incineration is a disposal method in which solid organic wastes are subjected
to combustion so as to convert them into residue and gaseous products.
This method is useful for disposal of residue of both solid waste management
and solid residue from waste water management. This process reduces the
volumes of solid waste to 20 -30 % of the original volume.
 An incinerator is a unit or facility used to burn trash and other types of waste
until it is reduced to ash. It is constructed of heavy, well-insulated materials,
so that it does not give off extreme amounts of external heat. The high
levels of heat are kept inside the furnace or unit so that the waste is burned
quickly and efficiently. If the heat were allowed to escape, the waste would not
burn as completely or as rapidly.
 Incineration and other high temperature waste treatment systems are
sometimes described as “thermal treatment”. Incinerators convert waste
materials into heat, gas, steam and ash.
 It is recognized as a practical method of disposing of certain hazardous
waste materials.
Advantages:
 Recovery of useful materials and energy
 Varying solid waste loads are converted to small volumes of ash
which can be controlled

Limitations:
 Controversial method of waste disposal, due to issues such as
emission of gaseous pollutants.
 Fly ash left in the furnace contains dangerous toxins which has
several adverse impacts on health and environment
 COMPOSTING
 Composting is a biological process in which micro-organisms, mainly fungi
and bacteria, convert degradable organic waste into humus like substance.
which looks like soil, is high in carbon and nitrogen and is an excellent medium
for growing plants, improves the soil conditions and fertility.
 Due to shortage of space for landfill in bigger cities, the biodegradable yard
waste (kept separate from the municipal waste) is allowed to degrade or
decompose in a medium.
Optimum conditions for composting
 Tempertaure – 40-50 °C
 Moisture – 40-70%
 Air - 0.5 to 0.8 m3/day/kg
 Carbon: nitrogen ratio - 35 to 50: 1
 Carbon:Phosphorus ration – 100:1
 Vermicomposting
 In Vermi-composting method, worms are added to the compost. These help to
break the waste and the added excreta of the worms makes the compost very
rich in nutrients.
Method
 To make a compost pit, you have to select a cool, shaded corner of the garden or
the school compound and dig a pit, which ideally should be 3 feet deep. This
depth is convenient for aerobic composting as the compost has to be turned at
regular intervals in this process.
 Preferably the pit should be lined with granite or brick to prevent nitrite
pollution of the subsoil water, which is known to be highly toxic. Each time
organic matter is added to the pit it should be covered with a layer of dried
leaves or a thin layer of soil which allows air to enter the pit thereby preventing
bad odour.
 At the end of 45 days, the rich pure organic matter is ready to be used.
 Benefits of composting

 Clean, cheap, and safe

 Compost allows the soil to retain more plant nutrients over a longer period.
 It supplies part of the 16 essential elements needed by the plants.
 It helps reduce the adverse effects of excessive alkalinity, acidity, or the
excessive use of chemical fertilizer.
 It makes soil easier to cultivate.
 It helps keep the soil cool in summer and warm in winter.
 It aids in preventing soil erosion by keeping the soil covered.
 It helps in controlling the growth of weeds in the garden.
 Significantly reduce the amount of disposable garbage.
 Increases the soil’s water retention capacity.
 RECYCLING AND REUSE
 Recycling is the recovery and reuse of materials from wastes.
 Solid waste recycling refers to the reuse of manufactured goods from which
resources such as steel, copper, or plastics can be recovered and reused.
Recycling and recovery is only one phase of an integrated approach to
solid waste management that also includes reducing the amount of waste
produced prior to composting , incinerating, and landfilling.
 Recycling keeps large amounts of solid waste out of landfills, conserve
resources, and save energy. The technology of recycling involves collection,
separation, preparing the material to buyer's specifications, sale to markets,
processing, and the eventual reuse of materials. Separation and collection is
only the first step; if the material is not also processed and returned to
commerce, then it is not being recycled. In many parts of the country, markets
are not yet sufficiently developed to handle the growing supply of collected
material.
 The materials recycled today include aluminum, paper, glass, plastics, iron
and steel, scrap tires, and used oil.
 Four R’s to be followed to manage the problem of solid waste
 The waste management hierarchy breaks this process down into four parts, also
known as the Four R's: Refuse, Reduce, Reuse, and Recycle. Most people
know them by heart as a slogan, but they're actually a hierarchy that starts with
the first and most preferable option, and goes down the ladder. Don't recycle
plastic, for example, when you can reuse it, or—even better—quit using it
altogether in the first place.
1. Refuse
 Cut down the waste simply by refusing to buy individually packaged items and
single-use plastics.
 By bringing metal straws and coffee tumblers for drinks
 Use of eco-bags for shopping instead of using paper and plastic bags
 Opt to receive the bills online instead of paper bills
 Avoid using disposable plates, utensils, and cups
2. Reduce
 Part of throwing away less is buying less, and being more mindful as a consumer.
Before you purchase something, consider whether you really need it, and how many
uses you’ll get out of it.
 Instead of buying cheap clothes that need to be replaced in a few months, invest in
well-made items that will last for years
 Take good care of your clothes, shoes, and bags so they don’t wear out as quickly
 Donate old clothes and any items in good condition to charity, instead of tossing them
out
3. Reuse
 Before tossing out your trash, consider whether it can be repurposed as something else.
 Use a chipped mug as a pen or toothbrush holder
 Re-use old jars, pots, bottles, and plastic tupperware
 Purchase rechargeable batteries
 Compost coffee grounds and tea bags and use them as fertilizer
 Turn single-use plastics into ecobricks
4. Recycle
After refusing, reducing, and reusing, recycling is the last resort in the
waste management hierarchy. Make sure to properly sort and clean your
items before bringing them to recycling centers.
Advantages
 Less utilization of raw materials
 Reduces environmental impacts arising from waste disposal and treatment
 Saves money, energy required to manufacture new products
 Reduces pollution
 Recycling paper will reduce deforestation
 Reuse of metals will reduce mining and melting of ores
 Saves land space
 DUMPING
 An open dumping is defined as a land disposal site at
which solid wastes are disposed of in a manner that does
not protect the environment, are susceptible to open
burning, and are exposed to the elements, vectors, and
scavengers.
 Open dumping can include solid waste disposal facilities or
practices that pose a reasonable probability of adverse
effects on health or the environment.
 It is the breeding ground for flies, rats, insects and
pathogens. The rain water from these dumps contaminates
nearby land and water thereby spreading diseases
 It is practiced extensively in India as it is cheap.
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