Question

Approximately what percentage of suspended solids is removed during primary sedimentation in a sewage treatment plant?

Options

• 10–20%

• 30–40%

• 50–70%

• 90–99%

Answer 1

In primary treatment, the sedimentation tank allows settleable particulate matter to precipitate as primary sludge, removing approximately 50–70% of total suspended solids and significantly reducing coliform counts.