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Hari was concerned about the stagnant water of his locality. He decided to take action regarding the issue. He advised his locality head that they should set up different plants to treat waste water. Mention the types of treatments to treat the same. |
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Answer» There are two types of treatment to treat waste water. (a) Primary treatment: It removes the physical particles from sewage by filtration and sedimentation. All solids that settle in setting tanks form primary sludge. Supernatant forms the effluents. (b) Secondary Treatment: Effluent from the primary setting tank is kept in large aeration tanks where useful aerobic microbes grow into floes. Microbes reduces Biochemical Oxygen Demand (BOD) of sewage. Effluent is then passed into a setting tank to form sediment, called as activated sludge. A small part of activated sludge is pumped back into the aeration tank to serve as inoculum. Remaining of sludge is pumped into large tanks called anaerobic sludge digester. Anaerobic bacteria digest the other bacteria and the fungi in the sludge. Effluent, after treatment is generally released into water-bodies like rivers and streams. |
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