| This thesis compares the restoration effects of different aquatic plants and their mutual combination systems on eutrophic water bodies,studies the synergistic restoration effects of aquatic plants’mutual combination on eutrophic water bodies,and analyzes the effects of plant absorption and assimilation and microbial action on the removal of nitrogen and phosphorus from water bodies.The remediation efficiency of biological carrier for eutrophication water was studied by immobilized microorganism with polyurethane carrier.Finally,the remediation efficiency of the combination of plant and biological carrier for eutrophication water was studied,and the synergistic remediation effect of plant and biofilm and the removal mechanism of major pollutants were explored.The main conclusions are as follows:（1）The absorption characteristics of the three aquatic plants were different,and the dominant bacteria genus and functional microorganism on the surface were different.The mutual combination of the three aquatic plants,Acorus calamus and Celiophora calamus,improved the diversity of nutrient absorption and the rate of absorption under different nitrogen and phosphorus concentrations,and increased the amount of absorption and assimilation of nitrogen and phosphorus nutrients by plants in the system.When the initial concentrations of NH4+-N,NO3--N,TN and TP were4.0,8.0,12.0 and 0.8 mg·L-1,the average removal rates of group Vallisneria natans+Acorus calamus+Eichhornia crassipes was the highest,which were 98.30%,79.80%,80.34%and 97.50%,respectively.（2）In phytoremediation system,plant absorption and assimilation is the main way for aquatic plant remediation to remove nitrogen and phosphorus,accounting for31.57%～52.43%of the initial TN content and 35.98%～67.68%of the initial TP content.Microbial and other functions are important ways for phytoremediation to remove nitrogen and phosphorus,accounting for 16.24%～42.73%of the initial TN content and 28.57%～72.17%of the TP content.Substrate adsorption contributed little to the removal of nitrogen and phosphorus,accounting for 2.53%～3.51%of the initial TN content and 0.80%～4.11%of the TP content,respectively.（3）The biofilm hanging time of the polyurethane carrier was 14～20 days.At the14th day,the biofilm attached to the surface of the carrier was basically stable.The number of bacteria attached to a single carrier was about 4×109,and the quality of biofilm attached to the carrier was about 0.20g.Carrier biofemm has a significant effect on the restoration of eutrophic water bodies.At the end of the 14d restoration experiment,the removal rates of NH4+-N,TN and TP by 2%carrier filling rate in water reached 99.0%,58.3%and 92.5%respectively,higher than that of 1%filling rate group.（4）In the dynamic repair experiment,the removal rate of NH4+-N,TN and TP in the plants+biofilm carrier group was the highest.When the influent concentration was 2.0,4.0 and 0.4 mg·L-1respectively,the effluent concentration was stable at0.2～0.5mg·L-1,0.5～1.2 mg·L-1and 0.03～0.10mg·L-1,with the highest removal rate reaching 89.0%,87.5%and 92.5%,respectively.（5）In the plants+biofilm carrier group system,plants growth was affected by the carrier,and the growth rate of fresh weight was 8.9%lower than that of the plant group.As the experiment goes on,the number of single carrier live bacteria decreased in both the biologic carrier group and the plants+biologic carrier group,and the biofilm activity also decreased.However,the plants+biofilm carrier group could effectively inhibit the shedding of biofilm and decrease the number of living bacteria.On the 28th day of the experiment,the bacterial content of a single carrier in the plants+biofilm carrier group was 37.9%higher than that in the biofilm carrier group.（6）High-throughput sequencing technology was used to analyze the microbial community structure in three repair systems:plant group,biofilm carrier group and plants+biofilm carrier group.The results showed that plants+biofilm carrier system enriched the diversity of functional microorganisms.Denitrification and phosphorus removal strains that did not appear in other systems or were much more abundant than those in other systems（such as nitrospira,Azohydromonas,Ensifer,rhizobia）were found.The biological combination purification system can not only improve the removal efficiency of nitrogen and phosphorus in water,but also enhance the stability of the purification system. |
