Simulation study on water purification of emergent plant floating island
According to the actual needs of environmental treatment and ecological protection of surface water ecosystem,phytoremediation technology,as an ecological remediation technology with low cost and wide application range,needs to be systematically discussed for water purification function of aquatic plant types and allocation modes.In this paper,aiming at the water purification problem of constructed wetland in micro-polluted water,five emergent plants,Typha orientalis,Iris tectorum,Canna indica,Lythrum salicaria,Sagittaria trifolia,and their different configuration modes were used to study the water purification function.On the basis of screening the dominant plants for water purification,the pollutant removal efficiency at different temperatures was discussed.The results revealed that the removal rate of ammonia nitrogen(NH4+-N)by aquatic plants in 30 days was more than 95％.Canna and Lythrum groups had the highest removal rates of of total nitrogen(TN)and total phosphorus(TP),and the removal rates of TN were 60.2％and 57.8％,and the removal rates of TP were 66.3％and 73.2％.Sagittaria arrowhead felled into the water body due to withering of plants,which led to the release of nitrogen and phosphorus into the water body,with the release rates of 18.7％and 43.0％,respectively.Root decay,denitrification and total phosphorus release appeared in Iris group.In the combined plant experiment,the combination of Iris,Canna and Lythrum showed better purification effect on polluted water than the combination of Typha,Canna and Lythrum,which was suitable for wetland and other ecological restoration measures to control micro-polluted water.The study on water purification efficiency of Canna,a dominant plant for water purification,at different environmental temperatures showed that the average TN and COD removal rate decreased significantly at low temperature(5～10 ℃).Moreover,the removal efficiency of COD,NH4+-N,TN and TP in micro-polluted water at 20～25 ℃ was significantly higher than that in low temperature environment.The diversity of bacterial community in rhizosphere fillers of composite floating island plants in normal temperature environment was higher than that in low temperature environment.Proteobacteria was the dominant bacterium in normal temperature environment,while Chloroflexi was the dominant bacterium in low temperature environment.
slightly polluted wateremergent plantwater purificationlow temperature
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