Question

In secondary treatment sewage, water is treated with __________.

• A. anaerobic bacteria
• B. biogas
• C. ammonia
• D. oxygen

Answer 1

The correct option is A

anaerobic bacteria

The correct option is A.

Explanation of the correct option:

1. Secondary treatment is the next step that involves the breaking down of organic matter by the action of bacteria. This can be done in open tanks called aeration tanks.
2. Aerobic bacteria act on the sewage in these tanks. Often; the air is blown into these tanks, Some times, anaerobic bacteria are used to break down the organic matter dissolved in sewage.
3. The process takes place in closed tanks or chambers.
4. In either case, the action of bacteria makes solids settle at the bottom. This is called biological or secondary sludge.

Final answer: In secondary treatment, sewage water is treated with anaerobic bacteria.