The polyhydroxyalkanoates characteristics of denitrifying and non-denitrifying phosphate accumulating organisms

This study investigated the polyhydroxyalkanoates (PHA) characteristics of denitrifying phosphate accumulating organisms (DNPAO) and nondenitrifying phosphate accumulating organisms (non-DNPAO) via a series of anoxic batch experiments in which the sludge was taken from a hybrid AS-biofilm pilot plant named the TNCU-I process. The results showed that 40.7% and 59.3% of the PHA was utilized in the anoxic and aerobic zones, respectively. Meanwhile, 47% and 53% of the phosphate was taken up in the anoxic and aerobic zones. The phosphate uptake amount per unit of PHA consumption (γPO4/PHA) in the anoxic and aerobic zones of the TNCU-I pilot plant were 0.83 mg PO₄-P/mg PHA and 0.64 mg PO₄-P/mg PHA. Furthermore, the batch experiments showed that the γPO4/PHA of DNPAO and non-DNPAO was 1.12 and 1.22 mg PO₄-P/mg PHA, respectively. The difference of γP04/PHA for non-DNPAO between the pilot plant and batch experiments may be caused by insufficient phosphate and the extra PHA consumption in the aerobic zone.