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This paper mainly discussed the treatment of rural non-point source sewage with the combination process of biological contact oxidation and the ditch wetland.With the experimental operation,water quality was continuously monitored and the amount of microbial population was statistically analysed and enzymatic activities were determined. The dominant bacterium of the biofilms in the fillers were isolated,purified and identified.The results obtained are shown in the following:1.The biological contact oxidation ponds were built in the demonstration engineering of the ditch wetland.The method of treating sewage was adopt in the wetland and the biology grilles were set to purity the sewage.The average removal rates of the TN,NH4+-N,CODcr and TP were 56%,66%,69%and 62%,respectively,in the rural non-point source sewage.The bacterium population take the leading position in the biofilms.The total amount of the microorganism was positively correlated to the average removal rates of the TN and CODcr.2.On the condition that the TN concentration was 70～80 mg/L,NH4+-N concentration was 30～40 mg/L,the CODcr concentration was 130～290 mg/L,the TP concentration was 10～13 mg/L and the hydraulic loading was 1.9～2.4 m3/m2·d in the simulated rural non-point source sewage,the average removal rates of the TN,NH4+-N, CODcr and TP were 67%,81%,84%and 64%,respectively.The system’s effect subjected to the fluctuation of water quality was small,which demonstrated that the combined system was stable.3.On the study of the functional bacterium of the biofilms in the simulated biological contact oxidation ponds,the amount of the functional bacterium increased as the rising of temperature.The amount of ammonifiers and denitrifying bacterium were significantly positive correlated to the average removal rates of the TN and NH4+-N.4.On the study of the relationship between enzymatic activities of the biofilms and the efficiency of purifying the sewage and the amount of microorganism in the combined system,the correlation between the urease activity and the average removal rates of the TN and NH4+-N was significant.And the urease activity was also positively correlated to the total amount of the microorganism.The correlation between the phosphatase activity and the average removal rate of the TP was not significant.The correlation between dehydrogenase activity and the average removal rate of the organic matter was also on a significant level.5.The dominant bacterium of the biofilms were separated,purified and identified in the combined system,which were Clostridium,Lactobacillus,Staphylococcus,Bacillus, Micrococcus,Alealigenes,Brevibacterium,Pseudomonas.It provides the reference of the microorganism to treat rural non-point source sewage.
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