In the sewage treatment,bacterial flocs are allowed to sediment in a settling tank. This sediment is called as

Identify the correct statement from the following.

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

In how many stages is the process of sewage treatment plants carried out?

Select the correct statement from the following.

Sewage or municipal waste should not be directly passed into rivers,streams and other water bodies because
$I.$ it contains human excreta and other organic waste
$II.$ it contains a number of pathogenic microbes
Which of the statement given above is/are correct?