Study On The Operation Efficiency Of Constructed Wetland For Treating The River Water Body Of Pollutant-absorbing Type

With the continuous development and progress of economy and society,water resources and water pollution are becoming more and more serious.This problem has become an important restriction factor affecting the sustainable development of our country.The Huaihe River basin is the key area of water pollution control and treatment in Henan Province.Shuangji River is one of its tributaries,which bears important agricultural irrigation,drainage and sewage discharge tasks.However,in recent years,the discharge of industrial wastewater and domestic sewage increased gradually.This situation has become a hidden trouble that restricts the sustainable development of local economy and the stable improvement of regional water environment quality.Therefore,the most important work of regional water pollution control is to restore the fragile ecological river system and regional water ecosystem.The construction of Shuangji River constructed wetland advanced treatment project is helpful to improve the water quality of Shuangji River and optimize the ecological environment.This study is based on the water pollution control work of Shuangji River in Xinmi City.The water in Xinmi section of Shuangji River is treated by Shuangji River constructed wetland,and the purification effect is studied.It is hoped that this research can provide theoretical basis and technical reference for the river ecological management scheme of Shuangji River Xinmi section.At the same time,it provides ideas and references for the operation and management of the same type of river ecological restoration projects.Shuangji River constructed wetland in Xinmi City was selected as the research object.Continuous water sample monitoring and microbial analysis were conducted from July 2019 to December 2020 for 18 months.The ability of the combined constructed wetland system to remove pollutants was investigated.The main factors affecting the operating efficiency of constructed wetland include season,water temperature and dissolved oxygen.In this paper,the relationship between the growth of substrate microorganisms and the removal efficiency of pollutants in surface flow and vertical subsurface flow constructed wetlands was analyzed by using the high-throughput sequencing technology of bacterial 16S r DNA gene.The main results and conclusions were summarized as follows:（1）The combined system of Shuangji River constructed wetland has a certain purification effect on the river water.The average removal rates of COD_Cr,COD_Mn,NH₃-N and TP were 26.35%,21.48%,47.63%and 31.41%,respectively.The wetland has the best removal effect on ammonia nitrogen and total phosphorus.The effluent water quality indexes can meet the requirements of Class IV of the Environmental Quality Standard for Surface Water.（2）In the purification efficiency of each unit along the combined constructed wetland system,the surface flow constructed wetland segment and the vertical subsurface flow constructed wetland segment contribute more to the removal of pollutants.The average removal rates of COD_Cr in these two sections are 19.13%and 23.08%respectively.The average removal rate of COD_Mn was12.88%and 16.62%,respectively.The average removal rate of NH₃-N was21.06%and 23.54%,respectively.The average TP removal rate was 6.24%and21.47%,respectively.（3）The main influencing factors of wetland purification efficiency are season,water temperature and dissolved oxygen.The removal rates of all pollutants showed significant differences in different seasons,and the overall trend was summer>autumn>spring>winter.There is a significant correlation between the removal rate of pollutants and water temperature.The concentration of DO has a great influence on the removal effect of COD_Cr,COD_Mn and NH₃-N,but a little influence on the removal effect of TP.（4）Microorganisms in surface flow constructed wetland and vertical subsurface flow constructed wetland substrates were analyzed by high-throughput sequencing technology.The results showed that there was abundant microbial diversity in the matrix,and the former was greater than the latter.Proteobacteria,Bacteroidetes and Nitrohelicobacteria were the most abundant bacteria,accounting for 86.03%of the relative abundance.The main denitrogenous bacteria are Bacillus,Nitrohelicobacter,Acinetobacter and Thiobacter.The main dephosphorization bacteria genera are thiobacter acinetobacter and bacillus.