The purpose of biological treatment of wastewater is to

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?

Polluted water can be purified by using

What is sewage? Through what is sewage water passed before being disposed of?

Which bacteria are used to treat sewage water?

The primary treatment of sewage water involves