question_answer

Describe the various steps involved in waste water treatment.

Answer:

Treatment of waste water involves physical, chemical and biological processes which remove physical, chemical and biological matters that contaminate waste water.

These steps are as follows:

(i) Waste water is passed through bar screens. Large objects like rags, sticks, cans, plastic packets, napkins get removed.

(ii) Waste water then goes to a grit and sand removal tank. In this the speed of the waste water is reduced to allow sand grit and pebbles to settle down.

(iii) The water is then allowed to settle in a large tank which is sloped towards the middle. Solids like faeces settle down at the bottom and are removed by a scrapper. A skimmer removes the floatable solids like oil and grease.

The sludge is then transferred to another tank where it is decomposed by anaerobic bacteria.

(iv) Then air is passed through clarified water to allow aerobic bacteria to grow, which consume the remaining organic waste. This water is then released into the water bodies.