Abstract
The effect of the different ratios of anaerobic-aerobic time on the efficiency of enhanced biological phosphorus removal (EBPR) from synthetic wastewater with acetate as carbon source was investigated. Three pressurized pure oxygen sequencing batch reactor (POSBR) experiments were operated with a final pressure of 0.05 MPa. The reactors (POSBR1, POSBR2 and POSBR3) were developed and studied at different anaerobic-aerobic ratios of 3 : 3.5, 3 : 2.5 and 3 : 1.5, respectively. The laboratory results showed that for the polyphosphate-accumulating organisms (PAOs) more polyhydroxyalkanoates (PHAs) accumulated and phosphate was released in the anaerobic stage, while higher concentration of phosphate was taken up in the aerobic period. However, the POSBR2 had a greater phosphate release to uptake ratio than POSBR1 and POSBR3, which resulted in a much higher phosphorus removal efficiency (93.8%) than the other two operations (70.7% and 53.1%, respectively) within 30 days of operation. It was also found that POSBR2 synthesized more PHAs than others. The highest PHAs storage was observed during the anaerobic phase of POSBR2. Due to the influence of the time ratios on the PHA concentration and consumption, the condition of POSBR2 was favorable for the existence of PAO and therefore, beneficial for the biological phosphorus removal process.
