| With the rapid development of industry and agriculture, pollution caused by wastewater containing ammonia has been becoming a worsening problem. Nitrogen pollution has caused eutrophication, and also has become a serious problem to the health of aquatic organisms and human beings. It is an important subject to develop economic and more efficient processes to remove nitrogen for environmental engineers. On the basis of the principles of traditional biological nitrogen removal and the advantages of membrane bio-reactor, an anoxic-aerobic MBR was designed to treat the ammonia wastewater. In the experiment, the running performance and impact factors of the process and the membrance fouling were studied.When the reflux ratio of mixture was 0,1,2,3 respectively, the removal efficiency of COD was higher and changed little, yet the removal efficiency of ammonia nitrogen and TN increased firstly and then decreased. When the reflux ratio was 2, the effect of the reactor was best and the average removal rate of COD, NH4-N and TN were 93.17%,92.76% and 67.60%.When the reflux ratio of mixture was 2, the reactor was in stable operation, C/N ratio was 0.5～5.0, COD, NH4-N and TN removal were increased as C/N ratio increased. When the influent C/N ratio was about 5.0, the average removal rate of COD, NH4-N and TN were 94.06%,93.21% and 68.73%. The experiment showed that:when the influent C/N ratio was low and the influent NH4-N was constant, increasing the influent COD was benefit for the removal of COD and nitrogen.When the reactor was in stable operation, the influent COD was stable, the volumetric load of NH4-N was 0.46kg/(m3·d), the average removal rate of COD, NH4-N and TN were 89.31%,86.17% and 64.21%. When the volumetric load of NH4-N was 0.68kg/(m3·d), the average removal rate of COD, NH4-N and TN increased to 94.88%,93.94% and 75.30%. When the volumetric load of NH4-N continued to increase, the removal rate of pollutants began to decline. When the volumetric load of NH4-N increased to 1.37kg/(m3·d), the average removal rate of COD, NH4-N and TN declined to 83.06%,74.61% and 53.74%.Dosing filler in the MBR could increase the biomass and form attached growth type and suspended growth type microbial mixtures. The nitrobacteria which has a longer generation time attaching to the carrier firstly maintained the system in a high concentration of nitrobacteria. The Dissolved oxygen gradient maked by the biofilm enabled the system to remove nitrogen more effectively. The Nitrification rate of the suspended sludge in the Aerobic tanks was 0.229/d, which was much higher than the conventional treatment process. The denitrification rate of the suspended sludge in the anoxic was 0.223/d.The activated sludge and membrane in the Membrane chamber contributed to the removal of pollutants little. The removal of pollutants primarily occurred in the anoxic aerobic tanks in this process.In the experiment, the membrane was washed with chemicals one time and with water twice totally. Washing with chemicals was better than with water. The operation and characteristics of the process were beneficial to reduce the membrane fouling.
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