Question

Select the correct statement from the following:

• A. Methanobacterium is an aerobic bacterium found in the rumen of cattle.
• B. Biogas is produced by the activity of aerobic bacteria.
• C. Biogas is pure methane.
• D. Activated sludge in sediment tanks is a rich source of aerobic bacteria.

Hint:

Aerobic bacteria play a vital role in wastewater management.

Answer 1

The Correct Option is D

The correct statement is: Activated sludge in sediment tanks is a rich source of aerobic bacteria.

(A) Methanobacterium - Incorrect: These are strictly anaerobic archaea in cattle rumen.

(B) Biogas production - Incorrect: Biogas forms through anaerobic digestion, not aerobic processes.

(C) Biogas composition - Incorrect: Biogas contains ~60% methane plus CO₂ and traces of other gases.

(D) Activated sludge - Correct: This sewage treatment component contains aerobic bacteria that digest organic matter.

The correct answer is (D), as activated sludge systems rely on aerobic microbial communities.

Answer 2

Methanobacterium is a genus of aerobic bacteria involved in the production of biogas in environments like the rumen of cattle. Biogas mainly consists of methane (CH4), which is produced by the anaerobic digestion of organic matter.

Methanobacterium is indeed an aerobic bacterium, but its primary role is in the production of methane through anaerobic processes, not aerobic.

Option (D) is correct because biogas is primarily composed of methane.