Question

Study the following statement 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 aerobic bacteria.

(iv) Biogas, commonly called as gobar gas, is pure methane.

• A. (i) and (ii)
• B. (ii) and (iv)
• C. (ii) and (iii)
• D. (iii) and (iv)

Answer 1

Answer: (B)

(ii) and (iv)