11th Class Chemistry Environmental Chemistry

  • question_answer 12) Have you ever observed any water pollution in your area? What measures would you suggest to control it?


    Water pollution is the presence of any foreign substance (organic, inorganic, radioactive or biological) in water which tends to degrade the quality so as to constitute a hazard or impair the usefulness of water. The common water pollutants are: (i) Oxygen-demanding wastes (ii) Disease causing agents (iii) Synthetic organic compounds (iv) Plant nutrients (v) Inorganic chemicals and minerals (vi) Suspended solids (vii) Radioactive substances (viii) Thermal discharges (ix) Oil Control of Water Pollution: (i) Septic tanks should be used for each house. This will reduce the flow of municipal sewage and human excreta towards river, lake or pool. (ii) Rivers, lakes, etc., should not be used for bathing and washing purposes. In this way, water sources are not polluted with detergents and germs. (iii) Too much use of pesticides which are not degradable should be avoided. These are highly toxic substances. (iv) Efforts should be made to increase the use of low grade or polluted water. Treatment of domestic sewage for industrial cooling is a good example of efficient use. Water reuse has a special significance in mining and similar industries where the water availability is less. These efforts will save fresh water from being polluted. (v) Waste water treatment techniques should be applied before the polluted water enters a river, lake or pool. Available waste water treatment processes can be physical, chemical or biological. Physical processes comprise screening, sedimentation, floatation and filtration. Commonly used chemical processes are precipitation, coagulation and disinfection while biological processes are biological filtration and the activated sludge process. In particular cases, the processes such as carbon adsorption, oxidation and reduction, ion-exchange, reverse osmosis, electrolysis, etc., are also used.  

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