Comparative Study on the Denitrifying Phosphorus Removing Characteristics of MWTPs Guilin China

The denitrifying phosphorus removal characteristics of three municipal wastewater treatment plants (MWTPs) with different process, i.e., the Carrousel system included anoxic aerobic stage (A/O), the anoxic-aerobic Carrousel system with separated pre-anaerobic tank (A/C) and the typical three-stage anaerobic-anoxic-aerobic process (A2/O), were investigated by examining the sludge roles on phosphorus release in anaerobic stage and phosphorus uptake with two different electron acceptors (oxygen and nitrate). The results indicated that the phosphorus release ability of A/O sludge was larger than that of the A/C sludge and the A2/O sludge. The A/C sludge had larger phosphorus aerobic uptake and denitrifying phosphorus removing capabilities (15.39 and 8.90 mgP/g VSS, respectively). The relative populations of the denitrifying phosphate accumulating organisms (DNPAOs) with the polyphosphate accumulating organisms (PAO) was calculated from the results of phosphorus uptake batch experiments with either oxygen or nitrate as electron acceptor, and ratios of DNPAO/PAO were 57.81% in the A/C sludge, 32.16% in the A/O sludge and 27.03% in the A2/O sludge.