Question

Study the following statements and select the incorrect ones.
(i) Physical removal of large and small particles through filtration and sedimentation is called primary sewage treatment.
(ii) Secondary sewage treatment is mainly a mechanical process.
(iii) Activated sludge sediment in a sewage treatment plant is a rich source of aeroic bacteria.
(iv) Biogas, commonly called as gobar gas, is pure methane.

Answer 1

Explanation:

Secondary treatment is also called biological treatment or microbial treatment.

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Answer 2

Answer:

it is the secondary treatment was also called biological treatment