Variation of Polyphosphate Kinase Activity in Activated Sludge during Biological Phosphorus Removal

In order to improve the operation stability of the biological phosphorus removal process,polyphosphate kinase(PPK) activity in activated sludge,phosphorus concentration and polyphosphate amount were determined using a reactor with anaerobic/anoxic/aerobic(A2/O) process and anaerobic/aerobic(A/O) process.The relations among the PPK activity,the phosphorus concentrations and the polyphosphate amount were analyzed,and variation of PPK activity was investigated.Both of the A2/O and A/O processes were operated with 6 h cycles,The A2/O process consisted of a 1 h filling/anaerobic stage,a 0.5 h anoxic stage,a 1.5 h aerobic stage,a 1 h settling/drawing and a 2 h idle stage.The A/O process consisted of a 1 h filling/anaerobic stage,a 1.5 h aerobic stage,a 1.5 h settling/drawing and a 2 h idle stage.The results showed that changes in polyphosphate amount and phosphorus concentration were fit with typical characteristics of the biological phosphorus removal process.However,there was no obvious correlation between PPK activity and phosphorus concentration or polyphosphate amount,suggesting that PPK is not a key restricting enzyme in the biological phosphorus removal process.