Question

In sewage treatment, decomposition of organic matter is done by _________ . It is the _________ stage treatment of sewage water.

• A. sedimentation, primary
• B. filtering waste materials, primary
• C. frequent agitation of water, secondary
• D. chlorination of water, tertiary

Answer 1

The correct option is C frequent agitation of water, secondary

Aeration is the secondary stage in the treatment of sewage that is followed after filtration. It is done by frequent agitation of waste water to provide sufficient air contact for microbes or bacteria to feed on organic matter. These microbes then decompose the organic materials and forms flocks, which can easily be removed later.