Civil Engineering MCQJE Level Civil Engineering
The BOD removal efficiency of a well-operated conventional activated sludge process (ASP) treating domestic sewage is typically:
Environmental EngineeringBiological TreatmentHARD
Choose the correct answer
A
40–55%
B
60–75%
C
75–88%
D
90–95%
Correct Answer
D. 90–95%
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Activated sludge process achieves 90–95% BOD removal under optimal operating conditions (MLSS 2000–4000 mg/L, F/M ratio 0.2–0.5 day⁻¹, SRT 5–15 days). Trickling filters achieve 75–85%; primary sedimentation alone achieves 25–40%.
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