In nature, there is nothing like waste because the apparent waste produced by one organism becomes input for another organism. Waste is becoming a problem nowadays because it is produced more than what the nature can handle.
An average man generates around 300 to 500 kg of waste per year. This figure reaches 700 kg for European countries. Just imagine the amount of waste in India where population is more than 100 crores.
Major waste producing sources are industry, agriculture, household, municipal, commercial and medical units, etc. It has been observed that urban areas generate more waste than the rural areas. Some wastes are not much harmful but some are hazardous.
- The waste may be solid, liquid or gaseous.
- Solid waste is generated from construction, demolition, mining, etc.
- Liquid waste is generated from sewage, tanneries, textiles and other factories.
- Gaseous waste is generated from the smoke released from the factories and vehicles.
WHAT ARE THE DIFFRENT SOURCES OF WASTE ?
Waste is generated from a number of sources. The major sources of waste are :
Modern living style generates a large amount of waste in all homes. Everyone uses a number of things which are used for some period of time and then thrown as waste like paper, plastic goods, batteries, glass, packing material in the form of cans, cartons, envelops, etc.
Maximum waste is generated from the kitchen like fruit and vegetable peels, leftover food, etc. Discarded thermometer is a very dangerous waste. It contains lead and can cause serious illness.
Insecticides are very toxic chemicals used at home which after mixing with water can travel to distant places and can damage the environment. Sharp edged things like blades, knives and scissors can injure anybody.
Cans of perfumes and batteries are very harmful wastes because they can ignite and injure anybody. Toilets generate waste in the form of human excreta. Paint material also generates harmful waste.
Some houses use coal and wood as fuel which leaves ashes as residue, oil and air. Thousands of flies breed on sites where domestic waste is dumped.
Industrial waste is the most environment threatening waste. Almost all industries produce large amount of waste. All industries need some raw material. Mining of raw materials generate a lot of waste.
Therefore, the very beginning of an industry starts with waste generation. Industrial waste
is not only large in volume but also hazardous.
Many industries generate gaseous waste that cannot be measured. The important industrial wastes are given below:
(A) Mining Operations : A lot of waste is generated in the mining operations. To reach the underlying mineral deposits in earth, a lot of topsoil has to be removed.
In some cases the overlying rocks are removed. A lot of dust is also released into the atmosphere. Tailings is another form of waste i.e., the waste material generated after the extraction of mineral from the ore.
Tailing is a significant threat to the environment because it can result in the generation of acids and alkaline drainage. Mining of uranium is risky because of radon gas that is released during the mining.
(B) Cement Factories : A lot of waste is generated during all stages of cement manufacturing. The most important waste comprises dust and gases that are released into atmosphere.
During quarrying of limestone, a lot of waste is generated in the countryside. Cement industry uses fuels like coal, petroleum and natural gas. All these fossil fuels also release waste.
(C) Oil Refineries : Petroleum in raw form is available in the form of mud. It is refined in the oil refinery to get petrol, diesel, kerosene and a number of chemicals.
While refining, it releases a large amount of gaseous and liquid waste. A lot of waste is generated in the form of chemicals which is difficult to handle. Waste water from oil refineries poses a big problem.
(D) Construction Units : Construction waste is generated when some construction or demolition activity takes place involving buildings, roads, bridges, subway, flyover, etc.
This waste is solid and non- biodegradable like concrete, plaster, metal, wood, plastics, etc. Much of this waste comes to the municipal stream. These wastes are heavy with high density, bulky and occupy large storage space.
It is estimated that the construction industry in India generates about 10-12 million tons of waste annually. Where basements are constructed, a lot of earth has to be removed as waste.
(E) Thermal Plants : Another source of energy is coal. It is burnt in the thermal plants to make steam which runs the generator to produce power. Enormous smoke is released into the atmosphere.
When coal is burnt, other gases are also released along with the smoke as gaseous waste. Tons of ash is left behind as waste in the thermal plants after the burning of coal. It is very fine ash and, therefore, also called fly ash.
(F) Nuclear Power Plants : The nuclear power plant generates a large amount of energy but its wastes are the most harmful. Uranium and plutonium are major raw materials used in the generation of nuclear power.
Its waste remains radioactive for thousands of years. Therefore, such a waste can bring harm even to the coming generations. Various methods are being discussed at the international level to dispose off this waste.
Sometimes radioactive material leaks from nuclear plants in case of accidents. This material is capable of destroying life in the surrounding regions.
(G) Textile Industry : This industry produces cloth. Varieties of fibres are used in the textile mills like cotton, wool, silk, synthetic material, etc.
A large amount of water is used to dye the fibres. When this water is released as waste, it gets mixed with a number of chemicals and becomes toxic. This way liquid waste is produced which can damage the environment.
(H) Iron and Steel Industry : The iron and steel industry is also known as mother industry because all other industries depend upon it for machinery. The raw materials of this industry are coal, lime, manganese, iron ore and water.
All of them leave a large amount of waste. To make one ton of steel, more than one lakh litres of water is required. Large amount of ash and dust is left as waste. Many acids like sulphuric acid, hydrochloric acid, ete. are released. Large amount of smoke or gaseous waste is also released into air.
(I) Tanneries : Tanneries are the factories where leather is made from the skins of dead animals. These skins are tanned with chemicals.
It is interesting to note that the skins of dead animals can decompose easily but the leather is not easily decomposed. In the process of making leather, the tanneries add solid, liquid and gaseous waste.
The liquid waste released by tanneries is very toxic and gives out foul smell. It can even pollute the groundwater. Alcohol are manufactured at the distilleries which consume a lot of water, grains and molasses.
A large vessel known as still is used to distill. A large amount of waste is left in this still. Apart from the above mentioned sources, the waste is also generated by several other sources like paper industry, sugar industry, fertiliser industry, rubber industry, etc.
Agricultural practices generate a large amount of waste. Agriculture includes ploughing, sowing, harvesting, threshing, winnowing, poultry farming, dairy farming, etc.
include both natural (organic) and non-natural wastes. After harvesting the crop residue or plant remains is the main waste generated from the agricultural activities.
Threshing of food grains also generates a lot of waste. Threshing is a beating action that separates the seeds from the husk and stem of the plant. Nowadays, huge machines are used for threshing. They are called threshers.
These machines release large amount of straw and dust as waste which affects severely the asthma patients. Activities of dairy farming and poultry farming also generate a lot of animal waste.
The waste of agriculture differs from the industrial waste. The agricultural waste is biodegradable and does not damage the environment in a big way unlike industrial waste that is toxic, non-biodegradable and harmful to the environment.
Further, the agricultural waste, if handled or managed properly, can be useful to man. Much of theagricultural waste can be used to generate energy. Many farmers burn the crop residue in the farm itself. It not only kills life in soil but also pollutes the air.
This waste can be used to generate energy. Similarly, animal waste along with other plant material can be used in a compost to make manure. The manure can be used in fields to promote the growth of plants. Manure is also suitable for the health of soil.
The municipal waste includes the solid and liquid waste generated by homes and offices. The solid waste is disposed of as garbage in the containers and liquid waste is released as sewage in the pipelines or open drains.
Municipalities often dispose of the solid and liquid waste in the low lying areas or the water bodies. Solid waste is dumped in the open dumps or landfills.
Sometimes the solid waste is disposed of in the incinerator. The liquid waste or sewage is often released in the nearby river or other water body or any low lying area.
Disposing such untreated waste can pollute the environment and damage the adjoining areas. Much of this waste is biodegradable like paper, fruit and vegetable peels, etc.
But some non- biodegradable waste is also released like plastic goods, glass, etc. Both types of waste should be handled separately.
E-waste or electronic waste is generated from the discarded electronic devices like computers, cellphones, televisions, etc.
In many parts of the world, the governments are not yet prepared to handle this type of waste. In most parts of the world, specially the developing countries, the processing of e-waste causes serious health and pollution problems.
Heavy metal is the major concern for e-waste. In the USA alone more than 70% of heavy metals in landfills come from the e-waste. Lead, mercury and cadmium are major toxic substances in e-waste.
Besides, several chemicals and plastic material are also associated with the e-waste. The e-waste is not biodegradable and most of this waste cannot be recycled either.
Therefore, it is a source of worry all over the world. The volume of e-waste is growing enormously because people do not bother to repair the damaged device and discard it.
Growing technology also adds to the volume of e-waste because people prefer to get the newer model of a device and discard the older one.
TYPES OF WASTE
Over the last few years, the consumer market has changed considerably. Therefore, products are being packed in cans, aluminium foils, plastics and other such non-biodegradable items that cause extensive damage to the environment.
Further the agriculture, industry, transport, etc. are also undergoing tremendous changes. As a result, the types of waste generated from every sector are also increasing.The state of waste can be of three types.
It could be solid, liquid and gaseous waste. We call it garbage, sewage and smoke. But, here we shall study the waste types as under :
On the basis of decomposition of waste, the waste can be biodegradable or non-biodegradable. The biodegradable wastes breakdown and decompose in the soil.
Microorganisms like bacteria and fungi decompose the waste goods as simple compounds which are used as nutrients by other living organisms. The biodegradable waste includes fruit and vegetable peels, leaves, grass, wood, paper, clothes, wool, etc.
This way the waste is consumed totally and disappears without leaving any by-product. The biodegradable waste is of two types :
(a) Simple biodegradable : This type of waste gets decomposed quickly through natural processes like dead remains of animals and plants, faecal matter, etc.
(b) Complex biodegradable waste : Some waste material does not decompose easily and has resistance to breakdown. Such material remains in environment for a long time and as such may prove harmful.
Non-biodegradable waste includes that material which does not breakdown or decompose in the soil. The important non-biodegradable waste is made of plastic goods, polythene bags, synthetic clothes, metals, chemicals, radioactive waste, etc.
Since there is no natural process to decompose them, they continue to pile up. Some of non- biodegradable wastes arerecyclable such as plastic goods, metals, glass, etc.
It is more difficult to handle the non-biodegradable waste. The only feasible solution to the non- biodegradable waste is recycling. Plastic is the most common non-biodegradable waste. Nowadays it is used extensively in a variety of products.
However, research is going on to make plastic biodegradable by mixing starch with the plastic goods. When such a type of plastic is thrown as waste, the bacteria will consume starch and plastic molecules will break apart and decompose.
Styrofoam is another serious concern for the environmentalists. It is being used in disposable cups, plates, egg trays, etc. It requires petroleum to make the styrofoam. It is not recyclable and also releases toxic chemicals like styrene, especially when heated.
Cans are very popular these days as containers of food, drinks and sprays. They are made of tin, aluminium or other metals.
Although tin is corrosion resistant, acidic food like fruits and vegetables may cause corrosion of the tin layer. Nausea, vomiting, and diarrhoea have been reported after ingesting the canned food.
Glass is also a common container of liquids. The waste of glass may cause injuries to the person who handles the waste.
Most of the glass are silica-basedbut nowadays many inorganice and organic materials are also used to make glass like plastic which is used to make acrylic glass.
Besides plastic, several other materials are also added to make glass like carbon, metals, phosphates, borates, fluorides, etc. which are not environment friendly.
This waste is contaminated with infectious agents and is bio-hazardous. It can cause the spread of several diseases. Hospitals, clinics and nursing homes generate infectious waste which can be proved hazardous if not properly treated.
Activities like childbirth, operation, pathological tests, accidental treatments, etc. release contaminated waste. This waste includes the sharp-edged tools like knives, scissors, razors, needles, anatomical part, soiled dressings, expired drugs, cotton, pathological waste, etc.
Chemotherapy waste like gloves and towels contain many chemical therapeutic agents. Hospitals are the main source of such type of wastes. Everyday a number of patients visit hospitals and clinics.
Treatment of patients specially operations generate a lot of waste. Pathological waste like blood, body parts and tissues can cause infections. Healthcare and sanitation workers are always at risk while handling this waste.
Toxic waste is the waste material that can cause death or injury to living creatures and is called hazardous waste. Toxic wastes contain poison and are very harmful substances causing illness or death.
Most of them appear in the form of chemicals. They are part of the industrial, agricultural, household, medical waste. They are released on land, in air and water.
Lead, mercury and chromium are common effluents from industries. Agricultural practices release them by using insecticides and pesticides.
Some waste things do not pose any serious threat to the environment and health of people. Most of this waste comes from household activities and includes garbage like paper, fruit and vegetable peels, clothes, etc. This material easily gets decomposed without polluting the environment.