Reversed anoxic/anaerobic/aerobic process (reversed AAO) for removing nitrogen and phosphorus was developed in the middle of the nineties, last century. This paper mainly investigates the running effects, parameters and influence factors of reversed AAO process for treating, municipal wastewater in the second-stage project of the Song-jiang wastewater treatment plant (China) on full-scale. The nearly two-year operating results showed that CODcr, BOD5, SS, NH3-N and TN had good treatment efficiencies, the removal loading rates of TN and NH3-N were 0.022 kg TN.kgMLSS(-1).d(-1) and 0.026 kg NH3-N.kg MLSS-1.d(-1), respectively. However, PO4-P and TP removal rates were not high. Therefore, a simple improving measure was proposed to get higher TP removal rates. The operating results showed that reversed AAO process was feasible to remove nitrogen and phosphorus for newly-constructed wastewater treatment plants and upgrading existing wastewater biological treatment plants, which had low N and P removal rates.
