Which of the following is put into anaerobic sludge digester for further sewage treatment?

The correct option is B

Activated sludge

The correct option is B.

Explanation of the correct answer:

1. Activated sludge is the sedimented bacterial floc.
2. It is pumped into anaerobic sludge digesters where methanogens are present.
3. They digest organic mass and aerobic microbes.

Explanation of the incorrect options:

Option A:

Effluents of primary treatment are taken for secondary treatment with microbes.

Option C:

Primary sludge is the settled solid part that traps microbes and debris.

Option D:

Floating debris is removed by sequential filtration in the primary treatment.

Final answer: Activated sludge is put into an anaerobic sludge digester for further sewage treatment.