Indiscriminate use of water by increasing population and industrial expansion has led degradation of the quality of water considerably. Surface water available from rivers canals, lakes, etc. is never pure. It contains small quantities of suspended particles, organic and inorganic substances. When concentration of these substances increases, the water becomes polluted, and hence becomes unfit for use. In such a situation, the self-purifying capacity of water is unable to purify water.
Though water pollutants are also created by natural sources - erosion, landslides, decay and decomposition of plants and animals, etc. pollutants from human sources are the real causes of concern. Human beings pollute the water through industrial, agricultural and cultural activities. Amongst these activities, industry is the most significant contributor.
Industries produce several undesirable products including industrial wastes, polluted waste water, poisonous gases, chemical residuals, numerous heavy metals, dust, smoke, etc.
Most of industrial wastes are disposed off in running water or lakes. Eventually, poisonous elements reach the reservoirs, rivers and other water bodies, which destroy the bio-system of these waters. Major water polluting industries are leather, pulp and paper,etc.
