[Effect of phosphorus recovery on phosphorous bioaccumulation/harvesting in an alternating anaerobic/aerobic...

To improve the phosphorus (P) removal/recovery efficiency of a biological P removal system, the study used an alternating anaerobic/aerobic biofilter system to treat synthetic domestic sewage with a low carbon (C) to P ratio. The effects of using periodical carbon source amplification for P recovery on the P removal efficiency and the microbial characteristics within the biofilm were investigated. Intracellular storage polymer dyeing, scanning electron microscopy (SEM) observation and fluorescence in situ hybridization (FISH) methods were employed to characterize the changes of microbial communities in the biofilm during three continuous operation cycles of P bio-accumulating-P recovery (PB-PR). The results showed: through three cycles of operation process of PB-PR, the P removal efficiency of biofilter was increased from 60.3%, 82.9%, 86.6% (before P harvesting) to 87.2%, 91.2%, 93.5% (after P harvesting), respectively; the dominant microbial community morphotypes within the biofilter transformed from big cocci to small cocci, bacilli and filamentous and the group of phosphate-accumulating organisms (PAOs) got rising predominance, which was increased from 43% to 70% after three times of PB-PR; the proportion of PAOs in the biofilm increased unceasingly with the height of the up-flow biofilter. The results showed that the periodical carbon source amplification could improve the P removal efficiency of the biofilter and help the PAOs to become the dominant bacteria within the biofilm.