Characterization of polyphosphate-accumulating bacteria community structure in enhanced biological phosphorus removal reactor

In order to study the characterization of polyphosphate-accumulating organisms (PAOs) community structure in an enhanced biological phosphorus removal system, the phosphorus uptake of anaerobic-oxic (A/O) sludge and anaerobic-anoxic (A/A) sludge were investigated via batch tests. The experiment results indicated that the A/O sludge had a higher aerobic phosphorus uptake rate than the anoxic phosphorus uptake rate, however, the aerobic phosphorus uptake rate of the A/A sludge was less than the anoxic phosphorus uptake rate of that sludge. Based on these results, the presently used method, in which the ratio of the anoxic phosphorus uptake rate (qPa) to the aerobic uptake rate (qPo) gives the relative proportion of denitrifying polyphosphate-accumulating organisms (DPAOs) in the PAOs, is unreasonable. Furthermore, the PAOs community structure was related to the electron acceptor type. According to the type of electron acceptor, three groups of the PAOs could be proposed as follows: PON (using oxygen and nitrate as electron), PO (using only oxygen as electron acceptor) and PN (using only nitrate as electron acceptor).