In the activated sludge process, the F/M ratio (kg BOD applied per kg MLVSS per day) controls:
Choose the correct answer
The volume of the aeration tank only
The treatment efficiency and sludge characteristics (high F/M = low SRT = less treatment; low F/M = high SRT = nitrification possible)
The recycle ratio
The chlorine dose for disinfection
Correct Answer
B. The treatment efficiency and sludge characteristics (high F/M = low SRT = less treatment; low F/M = high SRT = nitrification possible)
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F/M = (Q x BOD_inf) / (V x MLVSS). Conventional AS: F/M = 0.2-0.4 kg BOD/kg MLVSS/day; extended aeration: 0.05-0.15; high-rate: 0.4-1.0. Low F/M = more complete treatment, more sludge age, higher degree of stabilization, potential for nitrification.
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