Basic Research On The Application Of Ecological Floating Bed To Control The Quality Of Landscape Water Supplemented With The Reclaimed Water

Due to its green economy and other advantages,ecological floating bed is increasingly widely used in the research and application of landscape water purification.However,it mostly stays in the laboratory simulation stage,and there are few studies on the coverage rate of floating bed,which limits the guiding significance of ecological floating bed to the actual landscape water purification.Based on this,this study first obtained the water quality characteristics,seasonal change rules and comprehensive evaluation status of reclaimed water landscape water through the long-term monitoring and TLI evaluation of the actual landscape water quality of one year of replenishment reclaimed water.At the same time,the water quality difference and the duration change between the control area and the floating bed purification area in the regenerated water supply section of the moat were tracked and studied,and the purification effect and existing problems of the ecological floating bed to the actual landscape water regenerated water supply area were obtained.In addition,the field pilot test lasted for 6months to optimize the optimal coverage rate of ecological floating bed purification and regenerated water supply landscape water,and analyze the mechanism and contribution of each purification approach.Finally,by summarizing the research results and literature analysis,the possible strengthening ways of ecological floating bed and the feasible research direction in the future are proposed.The main results and conclusions are as follows:（1）The results of the duration monitoring of landscape water replenishment with reclaimed water showed that the annual average annual total nitrogen concentration was5.08mg/L,and nitrate was the main form（nitrate/total nitrogen=83.33%）.The average annual total phosphorus concentration was 0.08mg/L,and organic phosphorus was the main form.Phosphate accounted for only 17.84%of the average annual TP concentration.The average annual algal density was 9.89×10⁷/L,which was positively correlated with temperature and turbidity,and negatively correlated with total nitrogen and total phosphorus concentrations.Microcystas aeruginosa was the dominant species,accounting for 77.95%of the average annual total algal density.In addition,the annual mean TLI was 44.70,belonging to the intermediate trophic level.（2）By comparing the water quality of the floating bed purification area and the control area in the actual landscape water,it can be seen that under the 3.31%coverage rate,the floating bed can remove 11.15%TN,14.89%NO₃,23.91%TP,50.0%phosphate and 22.04%COD in the water.The average annual densities of algae and chlorophyll a were 8.56×10⁷/L and 12.17×10⁷/L,and 24.53μg/L and 30.21μg/L,respectively,in the floating bed purification zone and control zone.Therefore,the floating bed has a certain purification effect on water quality,and has a certain control effect on water eutrophication,but the purification effect of the floating bed is very limited under low coverage rate.（3）In the floating bed coverage optimization experiment,the concentration of DO,p H,algae density and chlorophyll a concentration of water under different coverage rates all decreased with the increase of coverage rate.Considering the purification efficiency and economic cost,30%floating bed coverage rate should be selected,and the removal rates of TN,TP,NO₃^--N,PO₄^--P and COD in the landscape water replenishment by reclaimed water can reach 74.5%,81.4%,91.1%,94.6%and 38.0%,respectively.（4）The main sources of pollutants in landscape water with ecological floating bed are plant removal,natural settlement,water residual and water self-purification,etc.Under the condition of 30%coverage rate,the contribution rates of plant absorption and water self-purification to N removal are 34%and 41%,respectively.The contribution rates of P removal were 56%and 17%,respectively.The main ways to remove N in water are plant absorption and water subsidence,and the main contribution to the removal of P is plant absorption.