Study On The Purification Effect Of In-situ Integrated Ecological Purification Technology For Micro-polluted River Water

Due to the difference between the discharge standards implemented by the sewage treatment plant and environmental quality standards for surface water,the tail water of the sewage treatment plant is slightly polluted after being discharged into the river.The long-term existence of such water bodies is likely to cause damage to the water environment.Although the facilities such as constructed wetlands have been better water treatment effects,they cannot be widely applied in areas with limited land area and low investment budget.Therefore,it is necessary to select in-situ ecological purification technology to control micro-polluted rivers and carry out research.In view of the current situation of water bodies in the Qingyi River Basin,this paper studies the purification effect and influencing factors of in-situ purification integrated technology on micro-polluted water bodies,and summarizes the water purification mode.For this purpose,artificial floating islands,ecological riverbeds and ecological filter dams were preferred.The in-situ ecological purification integrated system was constructed,and the field experiment was carried out with the secondary effluent as the influent.The main conclusions of this study are as follows:?1?Through the analysis on the difference of purification effect between the in-situ ecological purification integrated system and the single technology in different seasons,the results showed that,when the river influent flow was 2400m³/d,the removal rates of COD,NH₄⁺-N,TP and TN by suspended ecological island,ecological riverbed and ecological filter dam were 0.86%⁸.01%;The integrated system area was about 500m²,the HRT was 2.8h,and the removal quantity were 19.9³7.2,1.6⁷.4,0.2⁰.5 and 8.3²0.4g/m²·d.The seasonal variation had obvious influence on the removal effect of the integrated system.The influent water quality of NH₄⁺-N and TN in different seasons was significantly distinct,which affected the removal of integrated systems.The temperature fluctuated alternately with the seasons,and the microbial activityandbiomasschangedrangewere0.037⁰.6mg/gand5.76×10⁷¹.112×10⁹cells/g,as well as the species and abundance of denitrification microorganisms in the summer river were higher than those in other seasons.The removal effect of the integrated system was affected and varies.?2?The variation of the purification effect of the integrated system under different influent flows was studied.The experiment found that when the influent flow were2400,800 and 400m³/d in winter,the removal rates of COD,NH₄⁺-N,TP and TN in the integrated system were 14.3%¹9%,7.8%¹5.5%,6.3%¹2.9%and 13%²2.8%;The flow change significantly affected the removal effect of NH₄⁺-N,TP and TN.when the influent flow were 2400,1200 and 800m³/d in summer,the removal rates of COD,NH₄⁺-N,TP and TN in integrated system were 23.7%²6.62%,18.19%²1.7%,23.8%³7.86%and 17.4%²3%;flow change only NH₄⁺-N removal effect was significantly different.Compared with winter and summer,the removal effect of winter integrated system was easily affected by the influent flow change.?3?Combining the analysis of singel technology,plants and microorganisms,revealed the changes of nitrogen and phosphorus pollutants in the integrated system,and established a set of water purification mode.The conclusion was as follows:the summer integrated system was in the influent flow 800m³/d,HRT for 7h,about 40.57g of TN can be removed,ecological riverbed I,ecological filter dam I and ecological riverbed II contributed about 15%,49%,8%and 27%to the removal of TN.In winter and summer,when the influent flow was 800m³/d,HRT for 7h,the integrated system could remove TP 2.779⁶.271g,suspended ecological island,ecological riverbed I,ecological filter dam I,ecological riverbed II and ecological filter dam II contributed about 16%,37%,22%,19%and 5%to the average TP removal.The ecological riverbed presented the best removal effect in the integrated system.According to the research on different seasons and different flow influencing factors of the river integrated system in the field test,with the purpose of water purification and self-purification,combined with the characteristics of the northern river and purification requirements,scientifically selected the combination of in-situ purification technology,rationally matched the superior aquatic plants,and run Conditional optimization adjustment,construction of in-situ ecological enhanced purification integrated technology system water purification mode,could provide technical and experience for similar river management.