Which of the following is used to digest the bacteria and fungi present in sewage sludge?

In how many stages does sewage treatment occur?

Given below are two statements about sewage. Based on them,select the correct option given below.
Statement $I$: The sediment in the settling tank is called floc.
Statement $II$: Sewage is first passed in the grit chamber,then it is screened.

In the sewage treatment process,the decomposer bacteria present in the waste are recycled at the beginning of the process. This is called.........

Measuring Biological Oxygen Demand $(BOD)$ is a method used for

Select the correct statement from the following.