Polyphosphate buffering by biomass with different phosphorus contents.

Polyphosphate buffering is a novel application of enhanced biological phosphorus (P) removal (EBPR) for P-deficient wastewaters with influent organic load variability. This study investigated the effect of biomass P content on polyphosphate buffering using a membrane bioreactor (MBR) and conventional bioreactor (CBR). Increasing the biomass P content increased polyphosphate buffering and the COD removal capacity, but at high P content (i.e. 20% P/TSS) the effluent P levels increased and a smaller fraction of available P was used for buffering. The MBR produced lower total effluent TSS levels and lower P levels than the CBR at both medium biomass P content (i.e. 12% P/TSS) and at low P content (i.e. 5% P/TSS) when the COD removal capacity was not exceeded. At high biomass P content, the MBR and CBR produced elevated effluent P levels. This study showed that the MBR does not make polyphosphate buffering feasible at high P content.