Effect of aeration intensity on the nitrogen and phosphorus removal performance of membrane bioreactors

The ability of simultaneous phosphorus and nitrogen removal of sequencing batch membrane bioreactor (SBMBR) run in anaerobic/aerobic (AO) mode was examined under three aeration intensities (2.5, 3.75 and 5.0 m³(m²·h)^-1). The results showed that the averaged removals of COD were over 90% at different aeration intensity. And the more aeration intensity was, the more ammonia nitrogen (NH₄⁺) removal rate got. The removal rates of NH₄⁺ under the three aeration intensities were 87.3%, 92.9% and 96.4%, respectively. Total nitrogen removal rate increased with the aeration intensity increasing, while excessive aeration intensity was disadvantageous to TN removal. The removal rates of TN under the three aeration intensities were 79.5%, 81.0% and 77.5%, respectively. Phosphorus release during anaerobic stage and uptake under aerobic/anoxic stage could be observed obviously in AO SBMBR system.