Analysis of the Activated Sludge Process in an MBR under Starvation Conditions

An aerobic membrane bioreactor (MBR) at complete biomass retention was studied over a period of time under starvation conditions. Kinetic parameters were determined in a no‐feed batch test. The decay rate of activated sludge, kd = 0.05 d–1, was determined by tracking the decrease of MLSS. The ratio of MLVSS/MLSS was in the range 0.76–0.85. The pH values were between 7.02 and 8.23. As a function of different initial concentrations of MLSS, specific nitrification rates qN, decreased from 4.23 to 0.02 mg‐N/(g MLVSS d) and specific biodegradation rates qb increased from 0.23 to 1.90 mg‐COD/(g MLVSS d). From experimental data the kinetic constants for respiration, which followed Monod kinetics, were determined as qO2max = 9.8 mg‐O2/(g MLVSS h), Kx = 2.9 g/dm3. Additionally, a linear correlation between MLSS and mean floc size was found to exist during the biodegradation process. An aerobic membrane bioreactor (MBR) at complete biomass retention was studied under starvation conditions. The decay rate of activated sludge was determined by tracking the decrease of mixed liquor suspended solids (MLSS). Specific nitrification rates and specific biodegradation rates were calculated as functions of the initial concentration of MLSS.