ICSE Class 9 Biology Chapter 19 Waste Generation and Management

Waste Generation And Management

Syllabus: Sources of waste - domestic, industrial, agricultural, commercial and other establishments. Domestic waste: paper, glass, plastic, rags, kitchen waste, etc. Industrial: mining operations, cement factories, oil refineries, construction units. Agricultural: plant remains, animal waste, processing waste. Municipal sewage: Sewage, degradable and non degradable waste from offices, etc. e-waste: brief idea about e-waste. Methods of safe disposal of waste: Segregation, dumping, composting, drainage, treatment of effluents before discharge, incineration, use of scrubbers and electrostatic precipitators. Segregation of domestic waste into biodegradable and non-biodegradable by households, garden waste to be converted to compost; sewage treatment plants.

What Is A Waste?

Waste is any substance which is discarded after primary use, or it is worthless, defective and of no use.

Ever since the human society has been evolving with huge population growth, there has been ever-increasing demand for the primary needs of food, shelter and clothing, etc. This has led to the rapidly increasing size and number of towns, cities, large agricultural fields, storage godowns, factories, interconnecting roads, railways and so on. With these, there has also been increasing use of electricity, firewood, petroleum and even nuclear energy. All this is leading to more and more human body wastes, livestock tastes, discarded equipments, agricultural wastes, etc. Efficient methods of their disposal are being continuously improved.

Categories Of Wastes

Broadly there are five major categories of waste:

Domestic waste given out from homes,

Industrial waste given out from factories, thermal plants, etc.,

Agricultural waste that is left behind after obtaining the consumable parts,

Municipal waste which includes the overall waste given out from the township, and

e-waste (electronic waste) from electrical and electronic equipment.

Domestic Waste:

An average home produces the following types of wastes:

Kitchen waste: Several items such as: - Peelings of vegetables and fruits, - Shells taken off from ground nuts and other dry fruits, and from eggs - Washing of pulses, rice, etc. before cooking, - Any stale or rotten non-usable food items, used tea leaves - Any left overs in the food dishes.

Plastics: - Plastic packings and wrappings - Discarded used and broken plastic objects including toys, etc.

Glass: - Broken glass utensils, mirrors, containers, window panes, electric bulbs.

Rags: - A huge variety of waste pieces of cloth, torn towels, handkerchiefs, etc. - Old bed sheets, blankets, cushions. - Discarded worn out clothing and footwear, curtains, and so on (Some of these are reused by the poor, or are sold off to the "raddiwalas").

Paper: The daily newspapers and magazines are a very common waste (which are generally sold off to "raddiwalas" who pass them on for a variety of use). Such waste paper is even recycled for their reuse in some way in paper industry.

Teacher's Note

When we sort our household trash into different bins at home, we are already participating in waste segregation - the first step toward responsible environmental stewardship.

Industrial Waste:

There is a huge variety of industries producing different types of materials and articles. All of these use raw material and give out a lot of waste. Some of these are as follows:

Mining operations: There are hundreds of mines in India alone and thousands in the world, which extract copper, silver, gold, zinc, iron, coal, etc. Huge quantities of waste are produced while processing them. Such waste is usually called mine tailing (the left-over). The mine tailing mixed with other materials can be used for making tiles, masonry cement, etc.

Cement industries: The wastes given out may be solid, liquid and gaseous. - The solid wastes are either used in construction activities or dumped in land-fills. - The liquid wastes including wash-offs are treated to remove harmful substances and then released into the rivers, ponds, lakes, or sea. - The gaseous wastes include the flyash which consists of fine solid particles of non-combustible ash carried out of a bed of solid fuel by a draft. It can be used for making a variety of building materials like bricks, concrete, roofing sheets.

Oil refineries: While refining crude oil a lot of poisonous gaseous and liquid wastes are produced. - Gaseous waste is cleaned by passing through cleaners, and purified part is released into the atmosphere. - The liquid wastes are processed and suitably dumped.

Construction units: These produce huge quantities of waste stones, pebbles, broken bricks, wood waste, etc. Mostly these are dumped in landfills. This is particularly a huge waste in large towns, and one sees heaps of landfills in the suburbs.

Teacher's Note

When we visit a construction site or a manufacturing facility, the heaps of waste materials we see are a stark reminder of how our consumption drives industrial processes and their environmental impact.

Agricultural Waste:

Agriculture is the art of cultivating the soil, producing crops and raising livestock (farm animals). The agricultural waste mainly includes:

Agricultural residues: The plant parts left after obtaining the usable portion. Much of this is used as animal feed.

Bagasse is the plant residue (as of sugar cane) after extracting the sugarcane juice. These are used as fire wood or in paper industry.

Pesticides and fertilizers collect into the soil and are washed of with the irrigation and rain water leading to river and pond pollution. Strict precautions have to be taken in their use.

Animal wastes include cow dung and other faecal matter which is used in making manure.

Municipal Waste:

Municipal waste includes the following:

Household discharge of excreta (faecal matter from toilets), and kitchen washings.

Discharge from public toilets, hospitals, hotels, restaurants, offices, etc. All this waste is carried away through sewers, and is called the sewage. This sewage is separated into: - the degradable part (capable of being broken down chemically into non-toxic parts) and - the non-degradable portion. Septic tanks are used to degrade the degradable part. The non-degradable part is dumped or buried at safe places.

Teacher's Note

Every time we flush a toilet or drain water from our kitchen, we are contributing to municipal sewage that must be treated before being released back into our environment.

e-Waste:

e-waste is the abbreviation of electronic waste. It consists of the discarded appliances using electricity, such as old computers, TVs, refrigerators, radios, cell (mobile) phones, mobile batteries, fluorescent tubes, electronic toys, medical instruments, lead-acid batteries, etc.

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