| The deterioration of water ecological environment is becoming more severe which caused by the acceleration of urbanization,the rapid increase of urban population and the hardening of road surface.Compared with other water pollution prevention and control technology,ecological ditch as a kind of non-point source pollution treatment technology which has advantages such as a small cover area,small engineering quantities,low investment,convenient for operation and maintenance,and excellent water treatment effect.And the technology have been widely applied in agricultural non-point source pollution control by researchers in recent years,however the improvement and its application for non-point source pollution prevention and control of water in the cold and arid regions urban is relatively rare.Integrating research results about ecological channels at home and abroad and combining with the regional landscape effect,the composite matrix contained slag,bricks,zeolite in accordance with the quality proportion of 3:1:1 have been determined according the early study,with spiral braid type biological packing as microbial carrier,Iris was used which has a good cold resistant performance and has the landscape effect as a water treatment plant.The oxic-anoxic ecological ditch has been built and was applied for pollution control in urban drainage channels in the study,in order to provide reference for ecological prevention and control of non-point source pollution in cold and arid regions urban.The test was accomplished during June 15,2019 to September30,2019,parameters such as the hydraulic retention time and water level had been discussed.The water environment application effect of the oxic-anoxic ecological ditch in cold and arid regions of urban non-point source pollution prevention and control,the microbial community structure in the ecological ditches,the difference of bacteria adhered on the biological packing and the surface of the substrate have been analysed and discussed.And the main results are as follows:?1?By the study on the operating parameters such as different hydraulic residence time and water level height of ecological ditch,it was shown that under the operating parameters of hydraulic residence time was 48 h and the water level height was 0.7 m,the ecological ditch had a relatively good removal effect for NH4+-N,TN,COD and TP,and the removal rates of them was 39.99%,43.52%,44.45%and 40.44%,respectively.?2?During the monitoring period from July to September,the surface hydraulic load of the oxic-anoxic ecological ditch was 0.33 m3/?m2·d?,and the daily treated water volume was 2.94m3.The average removal rates of NH4+-N,TN,CODCr and TP was 43.75%,54.08%,47.95%and 40.27%,respectively.And the effluent indexs could meet the standard above class V surface water in most of the time.In addition,the study showed that the operation effect of oxic-anoxic ecological ditch for the prevention and control of urban non-point source pollution in cold and dry regions was significantly affected by temperature?p<0.05?.During the August,the water temperature was mostly above 17?,the ditch had a good effect on the removal of pollutants,and the average removal rates of NH4+-N,TN,CODCr and TP in urban water in cold and dry regions were 47.11%,66.17%,52.42%and 49.61%,respectively.However,in September when the water temperature was mostly around 12?,the oxic-anoxic ecological ditch had a poor effect on the treatment of pollutants,and the average removal rates of NH4+-N,TN,CODCr and TP were 31.49%,36.43%,41.51%and 25.99%,respectively.Therefore,the application of the oxic-anoxic ecological ditch in cold and dry regions should be operated in summer when the temperature is high.?3?The analysis of the microbial community structure in each part of the ditches showed that the dominant phylum was mainly Proteobacteria,Actinobacteria,Chloroflexi and Firmicutes.The dominant genera were mainly Arthrobacter,norank-f-caldilineaceae,Steroidobacteraceae,Gemmobacter and Exiguobacterium.And the microorganisms attached on the surface of the spiral braid type biological packing in the oxic unit were mainly the Firmicutes,Actinobacteria,Acidobacteria,Nitrospirae and Arthrobacter,and their abundance was significantly higher than that in the combined matrix?p<0.001?.However,the dominant species of microorganisms in the combined matrix of the anoxic unit was mainly composed by Proteobacteria,Bacteroidetes,Steroidobacteraceae,Gemmobacter,unnamed norank-f-caldilineaceae and Arenimonas.The abundance of them was significantly higher than that in the spiral braid type biological packing?p<0.001?. |
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