Ncert Exercises & Solutions

Waste water treatment generates a large quantity of sludge, which can be treated by

1. anaerobic digesters

2. floc

3. chemicals

4. oxidation pond

(a) Sludge is further treated by anaerobic digesters. These are large heated tanks in

which its chemical decompositior is catalysed by microorganisms.

The liquid is created by bacteria whish breakdown bie urganic rater jeraining in solution. It is then

sent to oxidation ponds where hetrophic bacteria continue the breakdown of the organies and

solar UV light destroys the harmful bacteria. Chemical are not used in there treatments.

Page 184, XII NCERT