Experimental Research And Mechanism Analysis On Treatment Of Eutrophic Water Body By Plant Floating Bed

At present,the problem of water eutrophication in my country is still serious.Among the many technologies for treating water eutrophication,plant floating bed technology has the characteristics of low pollution,low cost and good effect,so it has been widely studied and applied.In this paper,based on the research of existing ecological floating bed technology,an ecological floating bed designed by PVC pipe itself was selected,and greenery,Vanda and copperweed were chosen as ecological floating bed plants by measuring the changes of parameters such as total organic carbon（TOC）,total phosphorus（TP）,electrical conductivity（COND）and chlorophyll a（Chla）in the configured eutrophic water bodies.The paper explores the differences in the effectiveness of three plants in degrading eutrophic water bodies under the same conditions.Also in this paper,the effect of extraneous conditions on the degradation effect was explored by controlling the planting density of greenery and the mass ratio of nitrogen to phosphorus in eutrophic water bodies,leading to the following conclusions:（1）Greenery,Vanda and copperweed were selected as floating bed plants to compare the plant growth and the purification effect of eutrophic water bodies.The results showed that all three plants survived,and the degradation trends of dissolved phosphorus（DP）,total nitrogen（TN）and total organic carbon（TOC）in each tank were basically the same.At the end of the experiment,the removal rate of DP,TN and TOC was faster,the conductivity（COND）decreased by 36.88%,and the chlorophyll a and algal density were lower.This indicates that Vanda lily has a good inhibitory effect on algae and can be used as a high quality floating bed plant for eutrophic water treatment.Copperweed was the second most effective for eutrophic water bodies and is also a better choice as a floating bed plant.This has important reference value for the selection of floating bed plants.（2）To investigate the optimal planting density of green lilies as floating bed plants for the treatment of eutrophic water bodies,and to compare the growth of green lilies at different planting densities and the purification effect of each pollution index.The results showed that the decrease rates of DP,TN,TOC and COND were positively correlated with planting density.The greater the planting density,the smaller the proportion of plant weight increase.The smaller the chlorophyll a and algae density in the water tank,and the algae density has a significant correlation with chlorophyll a.Experiments have shown that the best planting density of the test realistic greenery was3.33 g/L,and the TN and TOC concentrations decreased by 93.70%and 87.45%,respectively.The planting density was too high and the treatment effect was not significantly improved.（3）In this paper,we investigated the effect of different nitrogen to phosphorus mass ratios on the growth of copperweed and the purification effect of each pollution index in the Investigate eutrophic water.When the nitrogen to phosphorus mass ratio was15.96,copperweed grew most luxuriantly,chlorophyll a was lower,conductivity decreased slightly,and TP decreased at a faster rate.Its ability to remove nitrogen in NH₄⁺-N,nitrite nitrogen and nitrate nitrogen states was stronger relative to other nitrogen-phosphorus ratio water bodies.The TOC degradation in the copperhead plant group was largely higher than that in the control group.High-throughput sequencing showed that samples with nitrogen to phosphorus mass ratios of 15.96 and 24.17 were enriched in the common genera Novosphingobium,Mucilaginibacter,Simplicispira,Sideroxydans,and Limnobacter with higher relative abundance and similarity.This suggests that the nitrogen to phosphorus mass ratio influences the abundance of the dominant genera in the colony.