Q23. Which of the following is put into Anaerobic sludge digester for further sewage treatment?

4. Activated sludge

Solution:
When BOD of sewage has reduced, the effluent is passed into settling tank. Here, the bacterial flocs settle, and the sediment is called activated sludge. A small part of the sludge is used as an inoculum in the aeration tank and the remaining part is passed into large tanks called anaerobic sludge digesters.

Q23.  Which of the following is put into Anaerobic sludge digester for further sewage treatment?