| With the improvement of people's living conditions and the change of dietary structure, the water quality constituents of city sewage have changed greatly, leading to the increase of nitrogen content and low C/N ratio.Denitrification reaction in the process of biological nitrogen removal needs sufficient carbon source. In terms of some wastewater with low organic concentration, a great deal of carbon source must be added , leading to the great increase of treatment cost. As a new effective technology in the field of water pollution control, ABR anaerobic reactor has a series of advantages such as simple technological process,low project investment,low operating costs,high treatment efficiency,great system stability and so on. Comparing with other high-rate anaerobic reactors, it can be used as a substitute for aerobic or pre-treatment technology, that has great significance to solute the problem of water pollution economically and effectively. ABR anaerobic reactor combined the characteristics of aerobic contact oxidation process with the averages of aerobic contact oxidation process. At present, it has not been reported about the research of nitrogen removal efficiency with ABR-biological contact oxidation in the process of municipal sewage treatment with low C/N ratio.On the basic of previous researches, biological nitrogen removal effects on high nitrogen, low C/N ratio municipal domestic wastewater was studied using ABR & Biocontact Oxidation Process. The tests included the design and installation of the reactor, the inoculated and acclimation of the sludge, startup operation of the reactor and the treatment effect in different HRT,mixed liquid recycle ratio and temperature.The experimental results showed that:1. ABR reactor reflects the new ideas of multi-phase anaerobic process. In the startup operation stage , selecting and separating of microbial morphology was automatically completed , and in every compartment of the reactor, domestication and cultivation the microbial adapt to the conditions in different compartment embodied the characteristics of microbial in Baffled anaerobic reactor. The ABR process combined the characteristics of Biocontact Oxidation Process, embodied the development trend of nitrogen and phosphorus removal methods.2. The experimental water was artificial sewage. In the case of no discharge of excess sludge, the COD concentration fluctuated between 240mg/L and 330mg/L. Then adjusted the concentration of ammonia nitrogen, maintained that C/N was 5 and mixed liquid recycle ratio was 2, temperature 25℃, using low-load starting mode which totally lasted 35d. In order to shorten starting running time, used the approach of shortening HRT step-by-step to increase the load of sludge. In the mature period, the average removal rate of COD was as high as 92.5%, the lowest concentration of effluent COD was 24mg/L; the average concentration of NH4+-N was lower than 24mg/L, the average removal rate was 60%; the highest removal rate of total nitrogen was 69.2%, the effluent concentration was lower than 19mg/L. High ammonia nitrogen concentration of influent and lack of carbon source become the main reason for nitrogen removal. At this point, it also showed that the system had been successfully activated.3. After the reactor in a stable stage, studied the best operation conditions for the system to run , that is the best HRT, reflux ratio and temperature conditions. The results show that in the range of the experiment, when the HRT = 10h, R = 250%, T = 30℃, the removal effect for COD, NH4+-N and TN were better.4. In the best operation condition , the results show that, when C/N ratio decreased gradually, the average removal rate of COD changed little and the average removal rate of TN decreased rapidly . The average removal rate is bad with a C/N ratio 2-4. When C/N ratio is 5, the average removal rate was about 75%, and TN concentration in effluent water was lower than 20mg/L, meeting《Discharge standard of pollutants for municipal wastewater treatment plant》(GB18918-2002) the first B standard . When C/N ratio is 6-7, TN concentration in effluent water was lower than 15 mg/L, meeting《Discharge standard of pollutants for municipal wastewater treatment plant》(GB18918-2002) the first A standard . From this we can see that the system has stable and highly denitrification efficient, at a relatively low COD /TN, the total nitrogen removal rate of up to nearly 88%. Aeration with traditional high-volume A / O process, the removal efficiency of total nitrogen increased about 20%. Compared with other low C/N ratio wastewater treatment processes, ABR & biocontact oxidation process has a good total nitrogen removal efficiency.The above result shows that the nitrogen removal efficiency with ABR-biological contact oxidation in the process of municipal sewage treatment with low C/N ratio was good. In this paper, basic research about the process is made, which provides a theoretical basis for the practical application and has some guiding significance and reference value.
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