Study On The Effect Of Combined Constructed Wetland System To Treat Campus Landscape Water

Combined constructed wetlands are considered to be the most effective way to purify polluted urban rivers.The wetland water treatment process is a complex physicochemical-biochemical process,in which the microorganisms in the wetland system play a dominant role in the water treatment process.However,these processes are often affected by many factors such as influent water quality,wetland combination,and operation process.This paper builds a combined constructed wetland system on the basis of surface water monitoring on campus,and analyzes the changes of physical and chemical factors and microbial communities in different treatment units with operating time through long-term operation to explore the impact on pollutant removal effect,Mainly draw the following conclusions.(1)The concentrations of TN,TP,CODcr,ammonia nitrogen,nitrate nitrogen and nitrite nitrogen in the influent are 8.89mg/L,2.50 mg/L,47.80 mg/L,4.25 mg/L,3.33 mg/L,0.23 mg /L.The effluent concentrations are: 2.66 mg/L,0.40 mg/L,22.80 mg/L,0.12 mg/L,0.33 mg/L,0.005.The ammonia nitrogen in the combined constructed wetland system can meet the national surface water environmental quality standard(GB3838-2002)Class I standard,and the TP effluent water quality can reach Class III and IV.The overall quality of COD effluent can reach the Class III standard.The water quality of TN effluent is inferior to Category V,but it has been greatly improved compared with the water quality of influent.(2)The DO concentration,pH,ORP and influent concentration of the three wetland units showed similar trends.The water temperature of surface flow wetlands is positively correlated with TP,PH and ammonia nitrogen,the ORP of subsurface flow wetlands are correlated with TN and TP,and the pH of vertical flow wetlands is negatively correlated with ammonia nitrogen.DO,ORP and nitrite nitrogen in surface flow wetland,water temperature and COD,water temperature and TN in subsurface flow wetland,ORP and TP removal rate in vertical flow wetland are positively correlated,DO and TN,COD in surface flow wetland,subsurface flow wetland DO and COD,ORP and nitrate nitrogen removal rate were significantly negatively correlated.(3)The number of OTUs obtained by clustering the actual sequencing quantities of the three wetland units was the highest in winter;the surface flow and vertical flow wetlands in spring and the subsurface flow wetlands in summer had the highest species richness.The surface flow and vertical flow wetlands in winter and the subsurface flow wetlands in summer have the highest species diversity.(4)The three wetland units have different types and numbers of microorganisms in different seasons,and the relative abundance of microorganisms in each wetland unit also varies.Pseudomonas and Microbacteriaceae belong to the dominant genus in the three seasons,and the relative abundance is highest in the vertical flow wetlands in spring.In addition to these two genera,the dominant genera in winter,spring and next season are Rhodobacteraceae,Sphingorhabdus,Rhodobacteraceae,Sphingorhabdus,Bacillus,Aeromonas in spring,Aeromonas,Clociciium,Sphingobium,Klebsiella in summer.Flavobacterium,Oxalobacteraceae in winter,Pseudomonas,Exiguobacterium,Sphingorhabdus in spring,and Aeromonas in summer are positively correlated with ammonia removal rate.Rhodobacteraceae and Ilumatobacter in winter,Chryseobacterium and Aeromonas in spring,and Parabacteroides in summer are positively correlated with COD removal rate.Rhizobium,Sphingorhabdus,Pseudomonas in spring and Aeromonas in summer are positively correlated with TP removal rate.In summer,Acinetobacter and Brevundimonas were positively correlated with nitrate nitrogen removal rate.In summer,Novosphingobium,Curvibacter,Arcobacter and nitrite nitrogen removal rate are positively correlated.