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Domestic Waste Water

Wastewater is generated from domestic, industrial and agricultural activities. Domestic wastewater is generally known as sewage. Sewage comprises spent wastewater from kitchen and bathroom (called sullage or gray-water) and wastewater from toilet (known as excreta or black- water). Sewage consists of 99.3 to 99.7 % of liquid and 0.3 to 0.7% of solids. The solids present in the sewage are of two types; organic solids, and inorganic solids. Organic solids are the substances derived from living things like produces from plant and animal. The organic solids undergo decomposition by the microorganisms. Examples of organic solids are carbohydrate, protein, and fat. Inorganic solids are inert materials that they do not undergo decomposition by the microorganisms and are inert fixed solids. Examples of inorganic solids are grit, salt, chemicals, metals etc.

These solids cause degradation of the environment if they are discharged into the environment as such. If these solids are removed from the wastewater the water can be reclaimed and reused. The purpose of the wastewater treatment is, therefore, to remove the solids present in the wastewater.