Abstract: A coupling bioreactor based on the flow separate and multi-phase reaction principle is designed to study the nutrient removal and the effects of the sludge reduction.And a dynamic circular bioreactor is developed on the basis of the theory to investigate whether the sludge in the porous carriers has been decompounded in anaerobic environment or not.The influent loading of COD is from 0.80 to 1.20kg/(m³·d),the concentration of NH₄⁺-N and TN is from 70 to 90 mg/L and 75 to 110 mg/L respectively,hydraulic retention time and temperature in bioreactor is 8 hours and 25℃.The results show that the removal rate of TN is higher and the production of sludge is lower in the progress of micro-aeration+anoxic+aeration than those of whole aeration progress.The concentration of TN,TP and TC all increase and CH₄ is produced in the dynamic circular bioreactor.It can conclude that the sludge held back by the porous carriers was digested in anaerobic environment inside the porous carriers.Thereby,the sludge production is low and even has no sludge.