A novel wastewater treatment process termed by Alternating Activated Sludge Reactor (AASR) is proposed to treat wastewater for full-scale operation.AASR represents a certain technical development of Sequencing Batch Reactor (SBR) and Cyclic Activated Sludge Technology (CAST).The performance of AASR is in a satisfying level.The average effluent NH4+-N,TN,TP and COD concentrations are 0.5,17,0.8 and 40 mgL-1,respectively.The corresponding average removal efficiencies are 97,59,83 and 83 % respectively,indicating that the AASR is also a successful operating system for the organic matter removal.The AASR has many advantages,including successive filling,high removal efficiency,no sludge withdrawal,high stability and reliability,relatively easy process control,relatively low area requirement and low construction cost.The AASR shows higher efficiency in nitrification than the conventional SBR,due to the alternating anoxic,anaerobic and aerobic operational mode.The effective mode of denitrification is step-feed instead of sludge withdrawal.The control program of the AASR is highly flexible and can be easily modified by the plant manager in order to meet the requirement of higher or lower loadings or bacterial growth.