| Nitrogen pollution has become a serious problem to the health and survival of aquatic organisms and human beings. It is an arduous task for environmental engineers to develop more efficient and economic processes to solve this problem. On the basis of those existed nitrogen treatment processes, an anoxic-oxic hybrid MBR was designed to treat the low C/N ratio, high-strength ammonia wastewater.The effect of the hydraulic retention time in influent water on the removal efficiency of contaminations has been studied in this experimentation. When the water temperature was about 10℃, HRT was more than 10h, COD removal was decreased and NH3-N removal was increased appreciably as HRT prolonging.As the water temperature was 20~30℃, HRT was 10h, the influence of C/N ratio, volumetric load and shock loading on removal effect suggested that, when the influent COD was in the range of 156.3~1285.5mg/L, the total nitrogen was 198.5~285.6 mg/L, C/N ratio was 0.5~4.9, COD, NH3-N and nitrogen removal were increased as C/N ratio increased. When the influent COD was 1000mg/L, C/N ratio was 4.4, the COD, NH3-N and nitrogen removal were 91.5%, 90.3%, 60.2% respectively. The NO2--N /NO3--N ratio in the influent was about 1.78, with stable nitrite accumulation. Moreover, the system had the characteristic of high volumetric load. When the volumetric load of NH3-N was 0.36kg/m3·d, COD was 5.04 kg/m3·d, the system showed the best removal efficiency. The system had a high capacity in resistance to the shock loading, which was slightly influenced by the flux shock, COD and the ammonia concentration shock.The research indicated that the nitrogen removal process of hybrid MBR was based on the following two aspects. The first is that nitrification is mainly displayed in the oxic section and denitrification is dominantly carried out in the anoxic section and they harmonize with each other by circulation. Another is that nitrification and denitrification can be displayed simultaneously in each section.
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