SOLID WASTE MANAGEMENT

Solid waste is the unwanted or useless solid materials generated from combined residential,

industrial and commercial activities in a given area. It may be categorised according to its

origin (domestic, industrial, commercial, construction or institutional); according to its

contents (organic material, glass, metal, plastic paper etc); or according to hazard potential

(toxic, non-toxic, flammable, radioactive, infectious, etc).

Categories of wastes

1. Organic waste:

Kitchen waste, waste from food preparation, vegetables, flowers, leaves, fruits, and animal

excreta.

2. Combustibles:

Paper, wood, dried leaves, packaging for relief items etc. that are highly organic and having

low moisture content.

3. Non-combustibles:

Metal, Tins, Cans, bottles, stones, etc.

4. Toxic waste:

Old medicines, paints, chemicals, bulbs, spray cans, fertilizer and pesticide containers,

batteries, shoe polish.

5. Recyclables:

Paper, glass, metals, plastics.

Residue from fires that are used for cooking.

7. Construction waste:

iron rods, broken concrete etc.

8. Hazardous waste:

Oil, battery acid, medical waste, industrial waste, hospital waste.

9. Dead animals:

remains of dead livestock or other animals.

10. Bulky waste:

Tree branches, etc.

11. Soiled waste:

Hospital waste such as cloth soiled with blood and other body fluids.

12. E-waste:

TV, mobiles, etc.

Solid waste disposal:

The waste generated from residential, commercial and other sectors have become a cause for

concern due to the problems associated with their disposal. Therefore, their proper management

is extremely important. Improper disposal of solid waste cause air, water and soil pollution,

affect health of living organisms causing threat to their survival, etc. Solid waste management:

Management of solid waste reduces or eliminates adverse impacts on the environment and
human health and supports economic development and improved quality of life. A number of

processes are involved in effectively managing waste for a municipality. These include

monitoring, collection, transport, processing, recycling and disposal. Reduce, Reuse, Recycle:

Methods of waste reduction, waste reuse and recycling are the preferred options for managing

waste. There are many environmental benefits that can be derived from the use of these

methods. They reduce or prevent green house gas emissions, reduce the release of pollutants,

conserve resources, save energy and reduce the demand for waste treatment technology and

landfill space.

Methods like composting, sanitary landfill, pyrolysis and incineration are generally use to

manage solid wastes.

Sanitary landfill

This is the most popular solid waste disposal method used today. Garbage is basically spread

out in thin layers, compressed and covered with soil or plastic foam. Modern landfills are

designed in such a way that the bottom of the landfill is covered with a waterproof liner, which

is usually made of several layers of thick plastic and sand. This liner protects the groundwater

from being contaminated because of leaching or percolation. When the landfill is full, it is

covered with layers of sand, clay, topsoil and gravel to prevent seepage of water. Advantage:

If landfills are managed efficiently, it is an ensured sanitary waste disposal method.

Constraint:

It requires a reasonably large area. Incineration This method involves the burning of solid

wastes at high temperatures until the wastes are turned into ashes. Incinerators are made in such

a way that they do not give off extreme amounts of heat when burning solid wastes.

Incinerators that recycle heat energy through furnace and boiler are called waste-

toenergyplants. These waste-to-energy systems are more expensive to set up and operate
compared to plain incinerators because they require special equipment and controls, highly

skilled technical personnel, and auxiliary fuel systems. This method of solid waste management

can be done by individuals, municipalities and even institutions. The good thing about this

method is the fact that it reduces the volume of waste up to 20 or 30% of the original volume.

Advantage: The volume of combustible waste is reduced considerably by burning waste. In the

case of off-site pits, it is an appropriate method to minimize scavenging.

Constraint: It can cause smoke or fire hazard and also emits gaseous pollutants. Recovery and

Recycling Recycling or recovery of resources is the process of taking useful but discarded

items for the next use. Plastic bags, tins, glass and containers are often recycled automatically

since, in many situations, they are likely to be scarce commodities. Traditionally, these items

are processed and cleaned before they are recycled. The process aims at reducing energy loss,

consumption of new material and reduction of landfills. The most developed countries follow

a strong tradition of recycling to lower volumes of waste. Advantage: Recycling is

environmentally friendly. Constraint: It is expensive to set up, and in most emergencies, there

is limited potential.

Composting: Due to a lack of adequate space for landfills, biodegradable yard waste is allowed

to decompose in a medium designed for the purpose. Only biodegradable waste materials are

used for composting. It is a biological process in which micro-organisms, specifically fungi

and bacteria, and some arthropods like earthworm, convert degradable organic waste into

substances like humus. This finished product, which looks like soil, is high in carbon and

nitrogen. Good quality environmentally friendly manure is formed from the compost that is an

excellent medium for growing plants and can be used for agricultural purposes. Advantage:

Composting is environmentally friendly as well as beneficial for crops. Constraint: It requires

intensive management and experienced personnel for large scale operation. Pyrolysis This is a

method of solid waste management whereby solid wastes are chemically decomposed by heat
without the presence of oxygen. It usually occurs under pressure and at temperatures of up to

430 degrees Celsius. The solid wastes are changed into gasses, solid residue of carbon and ash

and small quantities of liquid. Advantage: This will keep the environment clean and reduce

health and settlement problems. Constraint: The systems that destroy chlorinated organic

molecules by heat may create incomplete combustion products, including dioxins and furans.

These compounds are highly toxic in the parts per trillion ranges. The residue it generates may

be hazardous wastes, requiring proper treatment, storage, and disposal.