Name: Sanitation at Public Places
Uploaded: 2019-07-19
Duration: 3 min 34 s
Description: We are aware that basic sanitation in our surroundings is a key necessity for healthy living. But, how can we maintain sanitation, and what are its true impl...

Question

Outline the main steps used in sewage treatment.

Accepted Answer

1. Screening:- It is first passed through screens of vertical bars, which remove large solid material like plastic bags, cans& sticks etc. Water is then passed through settling tanks, where solids such as sand, silt and gravel are settled.

2. Primary treatment:-Then waste water is passed into the sedimentation tank called clarifier. Here organic material settle down & removed with scrapper. This is called sludge. The floating materials like oil, grease, are removed with the help of skimmers. The water emerges from settling tank called clarified water. The decomposition is done by anaerobic bacteria, called digestion. It is used to obtain methane, ${CO}_{2}$ and humus.

3.Secondary treatment:-Then air is pumped through the clarified water in an aeration tank. This allows aerobic bacteria to grow & consume organic contaminants. Bacteria ultimately settle down at the bottom of settling tank as activated sludge. Then they are pumped back to aeration tank to be reused. The water is removed from the top. The dried sludge is used as manure.

4. Disinfection:-The water is then disinfected by chlorine or U.V Rays. This kills disease causing germs. The water can be now released into a water body for agriculture & Industrial uses.

Outline the main steps used in sewage treatment.

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