Purification Of Nitrogen And Phosphorus From Eutrophic Water By Aquatic Plants And Rhizosphere Microorganisms

With the rapid development of industry and agriculture,excess nutrients flow into the water ecosystem.How to repair eutrophic water bodies and restore natural water functional effects has become a hot issue.Due to its economic and aesthetic characteristics,the biological management method has strong practicality and has received extensive attention.Aquatic plants play an important role in not only absorbing nutrients,regulating the water environment,but also providing suitable living space for microorganisms and so on,so that nutrients can be further removed by other means.This paper analyzes the correlation between microbial community structure diversity and water quality indicators in the context of two different eutrophication types in Xi'an Ecological Zone.The effects of nitrogen and phosphorus removal efficiency and rhizosphere microorganism removal efficiency on aquatic plants in different seasons were studied,and the contribution rate of summer and winter plant action and microbial action to nitrogen and phosphorus removal in water was calculated.The main conclusions are as follows through this study:(1)The common species of reed rhizosphere microorganisms grown in two water bodies are Actinobacteria,Bacteroidetes,Armatimonadetes,Chloroflexi,Euryarchaeota,Proteobacteria,and Verrucomicrobia;the dominant populations are Proteobacteria.The composition of common and dominant populations in different seasons is not obvious,but its abundance varies in seasons.Its unique populations vary in different seasons.The rhizosphere microbes grown in the water body No.2 were more abundant than the No.1 water body,but the number of rhizosphere microorganisms in No.1 water body was more than that in No.2 water body.The number and population of microbes in autumn are more abundant than in summer.(2)The removal effects of nitrogen on four aquatic plants in different seasons are very different.In summer,water hyacinth has the best effect on nitrogen removal.In autumn,Elodea and Acorus calamus have the best removal effect on nitrogen.In the winter,Elodea has the best removal effect on nitrogen.Alternanthera philoxeroides and water hyacinth had the best effect on total phosphorus removal in summer,while Elodea and A.glabra had the best removal effect on total phosphorus in autumn,but the difference in total phosphorus treatment between different seasons was not as good as total nitrogen obviously.(3)The number of nitrosating bacteria and denitrifying bacteria is autumn>summer>winter,and the number of phosphorus bacterna decreases with decreasing temperature.There was a significant positive correlation between the number of nitrosated bacteria in the root zone of summer and the total nitrogen removal rate(p<0.05).The nitrosation bacteria in the root zone of autumn showed a significant positive correlation with the total nitrogen removal rate(p<0.01).There was a significant positive correlation between the denitrifying bacteria and the removal rate of nitrate nitrogen(p<0.01)and the total nitrogen removal rate(p<0.05).The removal rate of denitrifying bacteria and total nitrogen in winter root zone.A significant positive correlation was observed(p<0.05).(4)Rhizosphere microbial community structure in summer,the dominant population changed from Proteobacteria to Cyanobacteria.As the experiment progressed,the proportion of Cyanobacteria and Actinobacteria increased,Proteobacteria,Planetomycetes,Verrucomicrobia,thick-walled The proportion of Firmicutes and Bacteroidetes is reduced.The diversity of its species is also gradually decreasing.(5)The summer and winter aquatic plants have different mechanisms for the removal of nitrogen and phosphorus.In summer,they are mainly the role of plants themselves,while in winter they depend on microbial effects.The contribution rate of each part varies among different plants due to their own growth characteristics.The aquatic plant-microbial system has a certain regularity between the removal rate of total nitrogen and total phosphorus and the main influencing factors.This law can use the regression analysis theory to establish a mathematical model.