Given an anoxic/aerobic (MLE) activated sludge system that achieves 80% total nitrogen removal under the following conditions:

Operating at an MLSS of 2,500 mg/l, Biomass VSS = 1,850 mg/L; RAS TSS = 9,000 mg/l, Aerobic Volume = 1200 m3, Aerobic SRT = 12 days; Effluent Ammonia assumed to be < 1.0 mg/l (complete nitrification); Q= 2,000 m3/day, BODin = 200 mg/l, rbCODin = 80 mg/l, TKNin = 35 mg/l, Alkalinity = 220 mg/l as CaCO3; T = 16 degrees C.

Find: IR ratio and flow rate (m3/d)

Biomass produced each day (Px)

Anoxic Volume and HRT for anoxic reactor

Effluent alkalinity

Oxygen required for anoxic/aerobic (MLE) process versus system with no BNR calculate with and without oxygen credit from denite.