WATER POLLUTION:
Have you observed the rivers passing by the sides of the cities? How are they? Do these rivers contain clean water? Definitely the answer to this question is 'No'.
Most of such rivers are seen to have been converted into the sewers due to the pollution.
The term 'water pollution' is referred to the addition of an excess material (or heat) to water that is harmful to humans, animals, or desirable aquatic life.
The National Water Commission stated (1973) "water gets polluted if it has been not of sufficiently high quality suitable for the highest uses people wish to make of it at present or in the future."
The types of major sources of water pollution are
1. Domestic,
2. Industrial,
3. Agricultural and
4. Shipping waste waters.
1. Domestic water pollution
It occurs due to waste water from homes and commercial establishments.
Domestic waste water is collected from a wide area into the sewers which if not properly maintained may cause pollution in the nearby water bodies.
2. Industrial Waste and Effluents
Most of the Indian rivers and freshwater streams are seriously polluted by industrial wastes and effluents.
Such pollutants come along waste waters of different industries such as
- petrochemical complexes;
- fertilizer factories;
- oil refineries;
- pulp, paper, textile,
- sugar and steel mills,
- tanneries,
- distilleries,
- coal washeries,
- synthetic material plant for drugs, fibres, rubber, plastic etc.
In India all the 14 rivers have become polluted. Some most polluted rivers in Maharashtra like MulaMutha in Pune, Panchaganga in Kolhapur, Patalaganga in Panvel are heavily polluted having a variety of industrial and petrochemical wastes.
The river Ganga from Hardwar to Kolkata is regarded as one unending sewer which is fit only to carry urban liquid wastes, half burnt dead bodies, pesticides and insecticides.
Nearly 312 industrial units are dumping their waste into the river , only a dozen have effluent treatment facilities. About 27 cities contribute 902 million litres of waste water to the river each day. The water of Ganga affects the health of 250 million people of northern India.
3. Agricultural Water Pollution
It includes sediments, fertilizers and farm animal wastes.
These pollutants can enter into the water bodies from agricultural lands. The farm animal waste is a large problem from places where thousands of animals inhabit.
4. Shipping Water Pollution
It includes both human sewage and other wastes. The most important of which has been oil. The oil pollution, an oxygen demanding waste, is of concern not only from sensational major spills from ships and offshore drilling rigs but also from small spills and cleaning operations.
---------------------------------------------------------------------------------------------------------------
Not all water pollutants come from waste waters. Some water pollution is caused due to solid wastes that are not prevented from contaminating surface and ground water, and also caused due to the settling of air pollutants.
Most of the chemicals of industrial wastes have been toxic to humans as well as animals and may bring about death or sub lethal pathology of the liver, kidneys, reproductive systems, respiratory systems, or nervous systems in both invertebrate and vertebrate animals.
In Japan, illness and even death occurred in 1950s among fishermen who ingested fish, crab and shell-fish contaminated with methyl mercury from Japanese coastal industries. This mercury poisoning produced a crippling and often a fatal disease called Minamata disease.
Several water borne infectious diseases are directly related to polluted water. The heavy metal water pollutants causing health hazards in human beings are mercury, lead, arsenic, cadmium, selenium etc.
- Mercury causes abdominal pain, headache, diarrhoea, haemolysis, and chest pain.
- Lead causes anaemia, vomiting, loss of appetite, convulsions, damage of brain, liver and kidney.
- Arsenic causes disturbed peripheral circulation, mental disturbance, liver cirrhosis, hyperkeratosis, lung cancer, ulcers in gastro-intestinal tract and kidney damage.
- Cadmium causes diarrhoea, growth retardation, bone deformation, kidney damage, testicular atrophy, anaemia, hypertension, injury of central nervous system and liver.
- Selenium causes damage of liver, kidney and spleen, fever, nervousness, vomiting, low blood pressure, blindness and even death.
PREVENTION AND CONTROL OF WATER POLLUTION:
This can be done using various techniques/ ways such as
- stabilization of ecosystems,
- reutilization and recycling of wastes, and
- removal of pollutants
Stabilization of ecosystems
Stabilization of ecosystems is the most reliable way to control water pollution.
It includes
1. reduction in waste input,
2. harvesting and removal of biomass,
3. trapping of nutrients,
4. fish management and
5. aeration.
Species diversification and eco-balance should be restored to prevent pollution by following various physical and biological methods.
Recycling
Recycling of various kinds of wastes like paper pulp, municipal and industrial effluents, sewage and thermal pollutants can be done.
For example urban waste can be recycled to generate cheaper fuel gas and electricity.
One large size waste recycling plant already exists at Okhla near New Delhi. The total gas generation from the plant is about 0.6 million cubic feet per day having a heat value of 700-800 BTU per cubic foot.
A new technology of waste recycling and disposal has been introduced by a distillery in Gujarat. This technology not only help the distillery to treat 450,000 litres of wastes daily before letting the effluent into streams but also generate energy equivalent to that given by 10 tonnes of coal every day.
Removal of Pollutants
The various physicochemical techniques used for removal of chemical or radiobiological pollutants are
1. adsorption,
2. electrodialysis,
3. reverse osmosis and
4. ion-exchange.
Of these ,reverse osmosis has been commonly used to desalinate brackish water and also finds suitable, effective and economical method for the purification of water polluted by sewage effluents.
For the control of water pollution C.S.I.R. introduced the techniques for the removal of ammonia, mercury, phenolics and sodium salts. These techniques can also be used for the reuse of water after its decolourization.
Radioactive waste management:
The radiation from radioactive material is hazardous to health of all the living forms.
The radioactive substances are normally closely protected to avoid the emission from reaching the organisms. But due to atomic explosions and also due to atomic reactors a large quantity of radioactive material finds its way in the ecosystem. The atomic explosions are comparatively fewer but the radioactive waste from reactors is a constant feature.
The radioactive waste is normally disposed by land filling.
For land filling the deep pits are dug in desert areas or in the sea bottom to dispose the radioactive waste.
These pits are capped by concrete to avoid the contamination. In spite of all the precautions taken the waste leaks in the ecosystem.
Case study:
I. Case study of organic farming:
Integrated organic farming is cyclical and zero waste procedure.
Waste products of one process are used as nutrients for the other process so that maximum utilization of resources is possible.
Ramesh Chandra Dagar, a farmer in Sonipat, Haryana, includes bee -keeping, dairy management, water harvesting, composting and agriculture in a chain of processes.
It supports each other and is an ideal, economical, extremely useful and sustainable process.
Use of chemical fertilizers can be avoided for crops as cow dung can be used as manure.
Crop waste is used as compost, natural fertilizer or for producing biogas which can be used as source of energy for the farm.
This is the practice of integrated organic farming.
II. Case study of waste water treatment
Waste water including sewage can be treated by utilizing artificial and natural processes.
Suitable example of this is the town of Areata, along the northern , coast of California.
The town people created an integrated waste water treatment process within natural system.
The cleaning occurs in two stages-
1) The conventional sedimentation, filtration and chlorine treatment is given.
2) After this lots of pollutants like heavy metals still remain. A marsh land is developed and plants like algae, fungi, and bacteria were seeded in this area. Due to this heavy metals were neutralised and assimilated when water flows through these marshes and gets purified naturally.
3) Marshes also shows a biodiversity in the form of fishes, animals and birds.
