| Along with the development of economic, the growth of population and the accelerating urbanization process, as well as the continuing expansion of the scale increase higher costs for sewage treatment. Accroding to these situation, to establish decentralized sewage treatment in the district as soon as possible become an important tool to solve the problem of sewage disposal and conducive to the reuse of treated water,also it do good to the efficiency of social,economic and environment.This paper mainly discussed the treatment of district sewerage with the combination process of biological contact oxidation and constructed wetlands.The process of experiments were devided into two phases, the continuous aeration model of the combination process was used in the first phase and the intermittent aeration of the combination process was used in the second phase.At the first phase of the experiment, in the condition of higher level polluted influent water (COD is 156～432mg/L, NH3-N is 40.91～72.32mg/L, TN is 50.30～84.46 mg/L,TP is 4.11～6.50mg/L), the flow load is 0.125m3/m2·h in BCO, the flow load is 0.008m3/m2·h in wetlands, the continuous aeration of the combination process and as air-water ratio is 18:1, 15:1, 12:1 and 9:1, the combination process has good effects to COD and SS, and can meet the corresponding standard of emission and reuse,but according to N, P treatment it's ineffective and can not meet the request of emission and reuse. Aim to the reduction of pollution levels of experimental water during the summer vacation, we carried out an in- dependent study on the treatment of the district sewerage with low concentration. We adopt the continuous aeration model of low air-water ratio and in order to seek the best efficiency of the combination process on the treatment of the district sewerage with low concentration ,we enlarge the influent flow load as well.Experimental results show that when influent flow concentration is low (COD is 43～201mg/L, NH3-N is 3.21～25.08mg/L, TN is 16.92～38.40 mg/L,TP is 1.10～3.38 mg/L), the flow load is 0.125m3/m2·h in BCO, the flow load is 0.008m3/m2·h in wetlands, and the air-to-water ratio was 9:1, COD, NH3-N can achieve to corresponding standards, TN was at the basic standards but parts of TP can not reach the standard; when the influent flow concentration is more lower (COD is 35～79mg/L, NH3-N is 3.22～10.50mg/L, TN is 17.22～26.98mg/L,TP is 1.10～1.62mg/L), and the flow load is 0.125m3/m2·h in BCO, the flow load is 0.008m3/m2·h in wetlands, and the gas-water ratio was 4:1, all the major indexes meet the corresponding standard; when the influent flow load increased into 0.208 m3/m2·h in BCO (the influent flow load increased into 0.014m3/m2·h in wetlands) and the gas-water ratio was 4:1, the COD and NH3-N, TN standards can be achieved but TP can not meet the standard requirements.In view of the low effectiveness of the combination process on treating high concentration district sewerage (COD is 378～442mg/L, NH3-N is 47.19～75.33mg/L, TN is 60.75～85.73mg/L,TP is 4.21～7.12mg/L) when it runs continuously, the continuous operation of the combination process was changed by the intermittent operation. When aeration intensity is 4.0m3/m2·h and aeration time is 3h, 2h, the combination process has good effects on COD and NH3-N, the corresponding standards can be achieved; TN and TP can not meet emissions standards and reuse water standards but have high efficiency and no obviously difference was seen in their treatment efficiency; Integrated to 4.0m3/m2·h aeration intensity, the optimum aeration time of the combination process is 2 hours. When COD is 378～442mg/L, NH3-N is 47.19～75.33mg/L, TN is 60.75～85.73mg/L,TP is 4.21～7.12mg/L, aeration intensity was 3.0m3/m2·h, aeration time was 4 hours and 3 hours, the combination process has good effects on COD and effluent standards can be achieved but three targets of N, TN and TP can not meet the standards; Aeration for 4h, the average removal efficiency of NH3-N and TN is 10% higher than the average removal efficiency of aeration for 3 hours, the difference of the average removal efficiency of TP reached 21%; Integrated to 3.0m3/m2·h aeration intensity, the optimum aeration time of the combination process was 4 hours. Integrated to the efficiency of two aeration intensity corresponding to the aeration time and economical rationality, as aeration intensity is 4.0m3/m2·h, to determine the optimum conditon of the combination process was, filling for 0.25 hour, aeration for 2 hours, sedimentation for 1 hour, discharge for 0.25 hour.Aim at different concentrations of distrcit sewerage, this paper indicates that the operation mode of the combination process can be adjusted to meet the standards. Intermittent mode can be used for higher concentrations of distrcit sewerage and continuous mode of low air-water ratio can be used for lowwer concentrations of distrcit sewerage.
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