Analysis Of The Efficiency Of The Joint Operation Of The Reservoir And The Ecological Filter And The Purification Efficiency Of The Ecological Filter

Since the reform and opening up,with the acceleration of urbanization and the rapid increase of urbanization rate,Water environment problems have become increasingly prominent in china,among which the improvement of urban water environment is imminent.Taking the demonstration project as the research object,this paper establishes an in-depth understanding of the process flow and design parameters of the demonstration project through the water quality monitoring and investigation of the Feicui Lake watershed in Hefei City in the early stage and the actual exploration in the process of engineering design and construction.After the operation of the system,the treatment effect of its pollutants was monitored and analyzed for one year,and on the basis of the system operation,a small test device of ecological filter was built in the laboratory to conduct in-depth research on its sewage purification efficiency.The main research contents and conclusions of this paper are as follows:（1）The Emerald Lake demonstration project adopts the linkage of rainwater control tank-sewage treatment plant-ecological filter to treat rainwater mixed water and dry season sewage from rainfall.Water quality improvement target:in the near term（within 5 years after the completion of the project construction）to stably meet the surface class IV.water quality standard,and in the long term（between 5 and 10 years after the completion of the project construction）gradually meet the surface class III water quality requirements of some indicators.（2）Taking the E09 outlet with the widest range of catchment area in Emerald Lake as an example,the monitoring and characteristic analysis of the inflow water quality in the flow restriction well concludes:（1）There are obvious fluctuations between the pollutant concentration process line of dry sewage at the discharge outlet and the peak period change of residential water use.（2）Rainfall characteristics（cumulative rainfall,rainfall intensity,rainfall interval days and rainfall duration）are the most important factors causing the fluctuation of inflow pollutant concentration.（3）The average concentration of rainfall events showed that the concentration of pollutants in various indicators far exceeded the surface V.water quality standard stipulated in the"Surface Water Environmental Quality Standards".（3）The monitoring and analysis of the pollutant treatment effect at the two outlets（E09 and E12）of the demonstration project showed that they had good purification effect.The average removal rates of COD,total nitrogen,total phosphorus and SS by the reservoir unit at the E09 discharge were 39.4%,18.3%,57.7%and 61.4%,the average removal rates of COD,total nitrogen,total phosphorus and SS in the ecological filter unit were 61.7%,65.8%,45.3%and 52.8%,and the average removal rates of COD,total nitrogen,total phosphorus and SS in the whole system were 75.8%,71.9%,71.9%and 82.6%.The average removal rates of COD,total nitrogen,total phosphorus and SS by the reservoir unit at the E12 discharge were 41.9%,35.5%,35.5%and 39.5%,the average removal rates of COD,total nitrogen,total phosphorus and SS by the ecological filter unit were 42.7%,47.5%,26.8%and 41.3%,and the average removal rates of COD,total nitrogen,total phosphorus and SS in the whole system were 69.7%,57.3%,54.3%and 66.4%.For the removal location of pollutants,the dry season water is directly collected through the rainwater reservoir and sent to the sewage plant for treatment,and the rainy season water pollutants are treated through two parts,but mainly rely on the back end of the system,that is,the ecological filter is partially removed.（4）In the study of the effect of ecological filter system on water purification,the effects of plant planting density and influent carbon and nitrogen ratio on the sewage treatment efficiency of ecological filter were studied by setting up three groups of ecological filter small test devices,and the results showed that:（1）Plant planting density had a greater impact on the effluent quality of the system.Under the condition of smooth water flow,the higher the planting density,the better the removal effect of the ecological filter system on pollutants.（2）The carbon-nitrogen ratio of influent water has a great influence on the removal effect of organic matter and nitrogen.Under the condition of setting four operating conditions,the higher the influent C/N,the better the removal effect of COD and TN.However,the operating condition of 12 C/N in the influent water increases very little compared with the TN removal rate when the influent C/N is 15,and the carbon source in the system is too sufficient to inhibit the production of NO₃-N.（5）The actual operation status of the demonstration project and the operation efficiency analysis of the ecological filter device show that the factors affecting the normal operation of the demonstration project system include plants,carbon sources,temperature and system operation management.Appropriate increase of plant planting density,increase the ratio of carbon and nitrogen in part of the influent water of the ecological filter,regularly add carbon sources to the filter and strengthen the cleaning of internal components of the system can effectively optimize the operation effect of the demonstration project and minimize the loss caused by abnormal operation.Figure[43]Table[9]See[81]...