Performance and microbial community structure analysis of biological phosphorus removal system in different periods

In order to investigate the relationship between operation and biological community, different operational periods of biological phosphorus removal (BPR) including setup period, stable period and deteriorative period were analyzed in an anaerobic/aerobic sequencing batch reactor (SBR). PCR-DGGE protocol was employed for revealing succession of microbial community structure and changes of functional bacteria related to BPR in different periods. The setup period lasted 26 days, including lag phase and rising phase. During these two phases, phosphorus removal efficiency enhanced from less than 40% to 80%. After that, stable period started represented by stable phosphorus removal efficiency of more than 80%. Tetrasphaera elongate, Gemmatimonas aurantiaca and Uncultured γ-proteobacterium were dominant as functional microbes in stable period. Stable period lasted 80 days, and then the BPR went into deteriorative period with a phosphorus removal efficiency of less than 70%. Microbial community structure of stable period and deteriorative period varied greatly. Uncultured γ-proteobacterium, which acted as potential polyphosphate accumulating organisms (PAOs), was eliminated from the reactor while the major competitor Candidatus Competibacter phosphatis clone SBRQ22 increased significantly leading to deterioration of BPR system.