Restoration Effect Of Microfiber Ecological Floating Bed System To Eutrophic Water Of Huixian Wetland

Huixian wetland is the largest and the most researched karst wetland in China.Water pollution is becoming more and more serious due to the effects of dispersed aquaculture,agricultural non-point source and domestic sewage discharge,and it is very necessary and urgent to study on the present situation and restoration of the water environment and improve the water quality of Huixian wetland.This paper aims to research the latest water pollution situation of Huixian wetland and improve the water quality of Huixian wetland,and analyzes the water quality situation and eutrophication degree of Huixian wetland through scientific methods.At the same time,this paper also studies the effect of microfiber ecological floating bed on the water quality of eutrophicated water in Huixian wetland.The main conclusions are as follows:The temporal and spatial distribution characteristics of pollutants in Huixian wetland were obvious,TN polluted water most seriously,followed by DO and COD_Cr.The water quality of each point of Huixian wetland presented different degrees of pollution,and was in eutrophic state.Comparing the decontamination ability of floating bed plants in different seasons and the growth conditions in summer,it was found that the Canna indica and Pistia stratiotes mixed planting system had the best effect on the comprehensive removal of pollutants,followed by Pistia stratiotes,Canna indica,and finally Iris sibirica.Mixed system plants also grew best in winter and summer.According to the research on different influencing factors of microfiber floating bed,it was found that the removal rate of COD_Cr,NH₄⁺-N,TN and TP of the floating bed system reached a high level when HRT was 1.5d in the comparative experiment of optimal HRT,which were 70.2%,92.8%,62.1%and 78.7%,respectively.In the experiment of the best aeration measurement,it was found that the floating bed reactor had a better comprehensive removal effect when the aeration amount was 4 L/min,the removal rates of COD_Cr,NH₄⁺-N,TN and TP in water were 73.6%,88.4%,62.5%and 70.6%,respectively.The floating bed system had better water quality improvement effect under the condition of low influent load in the experiment of influent concentration load factor analysis,the removal rates of COD_Cr,NH₄⁺-N,TN and TP in water were 65.3%,83.8%,67.6%and 86.1%,respectively.The effect of EM bacteria on the water treatment was studied,and the result showed the removal effects of COD_Cr,NH₄⁺-N and TN were significantly improved in the floating bed system,and the average removal rates reached 84.4%,96.9%and 72.0%respectively.The microbial community structure and composition which sticked on the surface of roots and microfiber fiber filler were analyzed after not adding and adding EM bacteria in the experiment.A variety of phylum,class and genera changed,but the core genera still existed.The abundance of Arcicella,Sphaerotilus and Janthinobacterium increased under the action of EM bacteria,which enhanced the degradation of organic matter and denitrification in floating bed system.The floating bed system was treated to the actual eutrophic water of Huixian wetland with EM bacteria under the optimal operating conditions.It was found that the removal rates of COD_Cr,NH₄⁺-N,TN and TP of the floating bed system reached a high level in the actual eutrophic water,which were 72.1%,85.6%,68.8%and 70.8%,respectively.And the effluent concentration could reach the classⅢfor surface water.