What is the water obtained after the sedimentation process in sewage treatment called?

Which processes are used to remove physical particulate matter from sewage water?
$(i)$ Filtration
$(ii)$ Chlorination
$(iii)$ Sedimentation
$(iv)$ Biological treatment

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.

In sewage treatment,secondary treatment is considered highly significant,because

What are flocs?

Select the correct statement from the following.