Question

The average BOD removal in the primary sedimentation of sewage is:

• A. \( 30\% \)
• B. \( 50\% \)
• C. \( 75\% \)
• D. \( 80\% \)

Hint:

Primary sedimentation removes about 50% of BOD and 60-70% of suspended solids before secondary treatment.

Answer 1

The Correct Option is B

Step 1: In the primary sedimentation process, suspended solids settle under gravity, leading to a reduction in organic load. Step 2: The average BOD (Biochemical Oxygen Demand) removal in primary sedimentation is typically around 50%, while suspended solids removal is about 60-70%. Thus, the correct answer is (B) 50%.