In the secondary treatment of $STP$,the masses of bacteria associated with fungal filaments are called . . . . . . .

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.

During which stage of sewage treatment is the effluent mechanically agitated continuously?

Which bacteria digest the bacteria and fungi present in the sludge during sewage treatment?

Flocs means . . . . . .

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