Enhancement of Nitrogen Removal in an Intermittent Aeration Membrane Bioreactor

Abstract

An intermittent aerated membrane bioreactor was applied in laboratory scale to treat synthetic household wastewater. The system organic load and nitrogen load were 0.34 kgCOD⋅m−3⋅d−1 and 0.06 kgTN⋅m−3⋅d−1, respectively. The hydraulic residence time was equal to 12 h and very long sludge residence times were imposed. Intermittent aeration, with anoxic‐aerobic cycle of 30/60 minutes, was employed in the system. The results showed that 100% SS and >90% COD could be removed. The average removal efficiency of NH4‐N and TN was 99.7% and 80%, respectively. A linear relationship between the fouling rate and the MLSS, MLVSS concentration was founded. The denitrification seemed to be the rate‐limiting step for nitrogen removal. To enhance denitrification, the following strategies could be considered: 1) to select suitable aeration/non‐aeration cycle, 2) to control the aeration intensity, 3) to feed the system at the beginning of non‐aeration period, 4) to maintain high MLSS concentration.