Membrane bioreactor configurations for enhanced biological phosphorus removal

Abstract

A membrane bioreactor (MBR) bench-scale plant (210 L) was operated under two different enhanced biological phosphorus removal (EBPR) configurations, characterised by pre- and postdenitrification mode. Both configurations were operated at 15 d SRT in parallel to a conventional WWTP and fed with degritted raw water. Effluent PT-concentrations were very stable and low between 0.05-0.15 mg/L for both configurations at sludge P-contents of 2-3%P/TS. In contrast to aerobic P-uptake with postdenitrification anoxic P-uptake clearly dominated in the pre-denitrification configuration. N-removal was surprisingly high with up to 96% in the post-denitrification system without resorting to any carbon addition. During P-spiking (influent: -­40 mgP/L) the P-content increased up to 6-7.5%P/TS. However, a significant amount of P-removal was due to adsorption and precipitation.