Removal of suspended,floating,coarse and solid particles in sewage treatment is called . . . . . . .

Which gases are produced during the sewage treatment process?

Given below are two statements with reference to the secondary treatment of sewage.
Statement $I$: The $BOD$ of effluent increases.
Statement $II$: Flocs of bacteria consume the major part of the organic matter present in the effluent.
In the light of the above statements,choose the most appropriate answer from the options given below.

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

What does primary sludge consist of?

What is sewage? In which way can sewage be harmful to us?