Research On Water Quality Evaluation And Improvement Measures Of Typical Reclaimed Water Replenishing Rivers In Beijing Area

As a new stable water source,reclaimed water is widely used to replenish urban rivers and lakes at home and abroad,and it is an important water source to maintain the ecological environment of rivers and lakes.However,reclaimed water is rich in nutrients such as nitrogen and phosphorus.After being reused in urban water bodies,its special properties are more likely to cause eutrophication problems than natural water bodies.In severe cases,water quality deterioration such as fishy smells will also occur.In this paper,liangshui River and Qing River,which are typical regenerated water replenishment channels in Beijing,are taken as the research objects,and the water quality and eutrophication status of the two rivers are quantitatively described by the water quality identification index method and the logarithmic power function generalized index formula,so as to analyze the water quality change rules and find out the root causes of the problems.Type based on recycled water filling water river pollution control requirements,the further research on the wetland water quality purification technology,build a composite vertical flow-pilot test table flow artificial wetland research,summarized and artificial wetland effect on pollutant removal and purification mechanism of into the river to control pollution and reduce the pollution of the reclaimed water supply channel load with green ecological solutions,provide technical support for the reclaimed water river water quality security.The main research conclusions of this paper are as follows:(1)The S8,S9,and S10 sections of the lower reaches of Liangshui River are located in the urban-rural junction,affected by the pollution of scattered point sources,the water quality is poor,and the water body has a high degree of nutrition.In summer,due to the increase in temperature,the self-purification capacity of the water ecosystem is improved,the concentration of water environment indicators is lower,and the water quality is better than other monitoring times.However,due to the impact of rainfall overflow pollution,water quality deteriorates in certain periods.(2)The Q5 and Q6 sections of the lower Qing River are affected by scattered point sources along the way,and the pollutant concentration has increased,and the water quality is relatively poor.During the flood season,the water quality of each section is poor.Rainfall runoff into the confluence and rainfall overflow from the combined drainage outlet are the main reasons,causing river water pollution.(3)Through the construction of a composite vertical flow-surface flow constructed wetland pilot test,it is found that the combined constructed wetland system has a significant purification effect on various pollutants in the sewage.For TP,TN,and NH3-N,the final cumulative removal rate reached 80.68%,69.28%,91.13%,respectively,and the removal effect was more significant.For COD and BOD5,the removal effect mainly occurs in the first stage of the composite vertical flow wetland.Affected by the growth of algae,the effluent concentration after the surface flow wetland treatment increases slightly,but it is still far lower than the influent concentration.