Waste is unwanted or useless material left over after an activity. Waste is also known as trash, refuse, rubbish, garbage, and junk. Waste is directly linked to human development, socially and technologically. Most human activities, especially related to industrial development and innovation, manufacturing, use of manufactured products, transportation, etc. lead to the production of waste material.

The waste may be biodegradable or non-biodegradable. Sometimes waste may be recycled and reused. The waste may be categorized into many categories depending upon its source of generation and management.

 

SOURCES OF WASTE

 

Waste can be categorized into the following types on the basis of the source of its generation.

 

(i) Domestic waste
(ii) Industrial waste
(iii) Agricultural waste
(iv) Commercial waste
(v) Municipal waste
(vi) e-waste

 

Domestic waste

 

Domestic waste primarily includes waste generated by our domestic or household activities like in the kitchen. Domestic waste can be liquid waste or solid waste.

 

(a) Liquid waste includes kitchen drainage, bathroom/toilet drainage, sewage, excretory' waste of humans and animals.
(b) Solid waste includes the following:
Kitchen waste: leftover food, vegetable peels, discarded raw or cooked food.
Paper and plastics: Paper, plastic items, broken toys, tetra packs, gutka pouches, etc.
(c) Paints and chemicals: Paints, chemicals, spray cans batteries, shoe polish.

 

Broken furniture, wood, and leather.
Glass: Glass bottles, light bulbs, tube lights, broken glass utensils, mirrors, window panes.
Electrical and electronic items: Used batteries, broken gadgets, discarded electrical fittings, etc.
Soot and smoke from coal, firewood, cow dung cakes, kerosene oil.
Rags: Used and worn-out clothes, bedsheets, curtains, etc.

 

Industrial waste

Industrial waste is waste produced by industrial activity such as that of factories, mills, and mines. Sources of industrial waste are as follows:
? Industrial plants and power stations using coal and crude oil.
? Furnaces using coal, firewood, kerosene, and cow dung cakes.
? Cement, ceramics, glass, and asbestos industries.
? Mining and metallurgical operations.
? Oil refineries
? Construction units
? Paper, textile, and steel manufacturing units. Nuclear power plants

 

The industrial waste can be classified into the following types:

A. solid, liquid and gaseous waste

 

? Solid waste:
? Sludge from chemical industries
? Mining waste after excavation and concentration.
? Construction waste material
? Metal scrap
? Discarded machines, broken tools, machine parts.

 

? Liquid waste:
? Effluents from oil industries
? Effluents containing heavy metals and detergents.
? Industrial wastewater containing pollutants such as nitrates, chlorides, calcium, sulfides, heavy metals, and radioactive waste.
? Wastewater from tanneries, abattoirs, and hospitals.

 

? Gaseous waste:
? Oxides of nitrogen are produced by thermal power stations and factories.
? Exhaust emissions containing carbon and sulfur, suspended particulate matter (SPM).
? Toxic fumes like ammonia, hydrogen sulfide, steam, and water vapor in steam industries.
? Hydrogen sulfide from oil refineries and chemical industries.
? Hydrocarbons from the combustion of coal, oil, and petroleum.
? Dust from the cement industry and stone quarries.

 

B. Organic and inorganic wastes

 

? Organic waste:
? Waste from tanneries, sugar factories, distilleries, molasses, etc.
? Waste from food processing industries.

? Inorganic waste: Waste from chemical, fertilizer, and pesticide industries.

 

Agricultural waste

 

Wastes that are generated during agricultural activities and by livestock are called agricultural waste.
? Minerals and organic wastes from agriculture fields with phosphate and nitrogen fertilizers that reach lakes, rivers, and seas. The water becomes deoxygenated and cannot support aquatic life.
? Chemical fertilizers, pesticides, insecticides, and herbicides.
? Agricultural residue like plant parts, rice husk, etc. remained after obtaining the usable portion. It is usually used as animal feed.
? Bagasse is the plant residue (as of sugar cane after extracting sugar cane juice). It is mostly used as firewood or in paper manufacturing.
? Waste from food processing
? Animal waste as fecal matter, cow dung, etc. The toxic chemicals may enter vegetables, fruits, and other crops, enter the food chain, and affects the health of human beings and other animals.

 

Commercial waste

Commercial waste consists of waste from premises used for the purpose of trade or business or for the purpose of sports, recreation, education, or entertainment. The commercial waste includes the following:
? Waste is generated in hospitality industries like restaurants and hotels. This includes glass and plastic bottles, aluminum cans, plastic containers, tetra packs, leftover foods, other paper, and clothing waste.
? Waste generated from the printing press, photocopiers, etc. This includes empty ink cartridges, paper, plastic covers, emulsions/ developing solutions.
? Waste from computer peripherals used floppy diskettes and stationery.
? Medical waste such as used syringes, needles, soiled cotton swabs, body tissues, saline bottles, medicines and medicine wrappers, etc.

 

Municipal waste

Municipal waste or municipal solid waste (MSW) is waste that includes municipal sewage, household, and office waste, and other waste collected by a municipality within a given area.
Municipal waste includes both degradable and non-degradable waste from households and offices. Municipal waste can be degradable (that can be broken down chemically into non-toxic parts), and non-degradable.

 

Electronic waste or e-waste

Electronic waste or e-waste Electronic waste or e-waste is mainly loosely or electronic devices. Obsolete and broken refrigerators, mobile phones, computers, mixer grinders, stereo systems, and television sets, etc. are some examples

 

The processing of e-waste causes serious eg, pollution problems. Rapid changes in technology and low initial cost have resulted in a fast-growing surplus of electronic waste. Some e-scrap such as cathode ray tubes contain contaminants such as lead, mercury, cadmium, etc. which cause health hazards in persons handling these wastes.

The chemicals released from e-wastes such as heavy metals seep into soil and groundwater and cause health problems, e-waste also contains some valuable materials such as silver, copper, etc.

 

WHAT HAPPENS WHEN WE ADD OUR WASTE TO THE ENVIRONMENT?

 

In our daily activities, we generate a lot of material that is thrown away. What are some of these waste materials? What happens after we throw them away? Let us perform an activity to find answers to these questions.

 

We have seen in the chapter on �Life Processes� that the food we eat is digested by various enzymes in our body. Have you ever wondered why the same enzyme does not break down everything we eat?

 

Enzymes are specific in their action, specific enzymes are needed for the break-down of a particular substance. That is why we will not get any energy if we try to eat coal! Because of this, many human-made materials like plastics will not be broken down by the action of bacteria or other saprophytes.

 

These materials will be acted upon by physical processes like heat and pressure, but under the ambient conditions found in our environment, these persist for a long time.

 

Substances that are broken down by biological processes are said to be biodegradable. How many of the substances you buried were biodegradable? Substances that are not broken down in this manner are said to be non-biodegradable. These substances may be inert and simply persist in the environment for a long time or may harm the various members of the ecosystem.

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