Enriched experiment and endogenous characteristics of polyphosphate-accumulating organisms(PAOs)
聚磷菌富集实验及其内源特征探究

By means of measuring maximal anaerobic phosphate release rates (PRR), analyzing 16S rRNA with fluorescence in-situ hybridization (FISH) and observing membrane integrity by live/dead staining, the aerobic decay characteristics of polyphosphate-accumulating organisms (PAOs) in a biological nutrient removal (BNR) system and an enriched PAOs sequencing batch reactor (SBR) system were investigated. It was experimentally determined that a highly enriched culture of PAOs (91%) was obtained in the enriched PAO-SBR system by alternating the carbon source in the feed between sodium acetate trihydrate and propionate over a 36 d switching cycle, i.e., sodium acetate trihydrate (24 d) and propionate (12 d). The experimental results and calculations revealed that the decay rates of PAOs in the BNR and enriched PAO-SBR systems were 0.113 d-1 and 0.181 d-1, respectively, and the death rates were 0.048 d-1 and 0.036 d-1. In addition, the results also demonstrated that cell death contributed 42% and 20%, respectively, to the cell decay in the BNR and enriched PAO-SBR systems. In other words, the activity decay accounted for 58% and 80% of the total cell decay. For this reason, cell death was not a major factor causing the cell decay of PAOs, but activity decay was mostly responsible for this process.