NEETZoologyMicrobes in Human Welfare
What is the purpose of the settling tank in a sewage treatment plant?
Options
- ATo remove solid particles
- BTo produce biogas
- CTo digest the bacteria in the sludge
- DTo release the effluent into natural water bodies
Correct answer
A. To remove solid particles
Step-by-step solution
Once the BOD of sewage or waste water is reduced significantly, the effluent is then passed into a settling tank where the bacterial ‘flocs’ are allowed to sediment. This sediment is called activated sludge. A small part of the activated sludge is pumped back into the aeration tank to serve as the inoculum.