Simultaneous Nitrogen and Phosphorus Removal by Denitrifying Dephosphatation in a(AO）₂ Sequencing Batch Reactor

A 24 L working volume reactor was used for the research on simultaneous phosphorus(P） and nitrogen(N） removal by denitrifying dephosphatation in an anaerobic-oxid-anoxic-oxid sequencing batch reactor(（AO）₂SBR） system. The durations of each phase are: anaerobic 1. 5 h, aerobic 2. 5 h, anoxic 1. 5 h, post-aerobic 0. 5 h, settling 1. 0 h, fill 0. 5 h. The successful removal of nitrogen and phosphorus is achieved in a stable(AO）₂SBR. The effluent P concentrations is below 1 mg/L, and the COD,TN and P average removal efficiency is 88. 9%, 77. 5% and 88. 7%, respectively. The batch experiment results show that the durations of aerobic and anoxic phase influence the P removal efficiency. Some feature points are found on the DO, ORP and pH curves to demonstrate the complete of phosphate release and phosphate uptake. These feature points can be used for the control of(AO）₂ SBR.