Development Of Compound Ecological Floating Bed Based On Plant Fiber Foaming Filler

Since the end of the 20th century,China has developed rapidly and maintained rapid GDP growth,becoming the second largest economy in the world after the United States.However,while China is striving to develop productivity,the human and ecological security problems caused by water pollution are also prominent.Water pollution incidents caused by illegal discharge of sewage,accidental leakage of raw materials,and weak management or monitoring of water resources seriously affect water quality safety.Ecological floating bed technology is one of the river restoration technologies.It is widely used at home and abroad because of its advantages of high stability,strong durability,good landscape,inexpensive and convenient construction.However,the research on ecological floating bed tends to study on single emergent plant,and there are few studies on the effect of two and more emergent plant combinations,filler rate,aeration time ratio and water flow velocity on the purification effect of ecological floating bed.In this paper,the floating bed filler independently developed by Huashe Design Group is adopted.The effects of two and more emergent plant combinations,filler rate,aeration time ratio and water velocity on the treatment of polluted water by ecological floating bed are studied.The results showed that:（1）In the initial screening experiment of ecological floating bed plants of Canna indica,Thalia dealbata Fraser,Acorus calamus,Typha angustifolia and Phragmites australis,Acorus calamus,Phragmites australis and Canna indica had better treatment effect on raw water.The maximum removal rates of COD,NH₄⁺-N,TN and TP in Acorus calamus,Phragmites australis and Canna indica were 80.95%,99.32%,93.75%and 76.15%,86.31%,98.92%,85.53%and 81.54%,83.33%,99.64%,88.67%and 40%,respectively.（2）The four plant combinations based on Canna indica,Acorus calamus and Phragmites australis were as follows:Canna indica+Phragmites australis,Canna indica+Acorus calamus,Phragmites australis+Acorus calamus,Canna indica+Phragmites australis+Acorus calamus,which were planted in 1:1（1:1:1）to carry out ecological floating bed plant combination experimental study.Canna indica+Acorus calamus had better overall removal ability of pollutants.The maximum removal rates of COD,NH₄⁺-N,TN and TP reached 87.27%,98%,89.21%and 93%,respectively.（3）When Canna indica+Acorus calamus was selected as the plant layer,five different filler rates of 0,20%,40%,60%and 80%were selected to conduct the experiment on the effect of filler rate on the water purification capacity of floating bed.The floating bed with the filler rate of 40%had better removal ability of various pollutants and the maximum removal rates of COD,NH₄⁺-N,TN and TP were 77%,98%,93%and 74%,respectively.（4）When Canna indica+Acorus calamus was selected as the plant layer,the filler rate was 40%and the aeration intensity was 1L/h,four different aeration stop times were selected as continuous aeration,stop 2 hours for aerating 4 hours,stop 4 hours for aerating 4 hours and stop 8 hours for aerating 16 hours.Stop 2 hours for aerating 4 hours had better treatment effect for TN.The maximum removal rates of COD,NH₄⁺-N,TN and TP were 76.5%,98%,97%and 64%,respectively.（5）When Canna indica+Acorus calamus was selected as the plant layer,the filler rate was 40%,the aeration stopped for 2 hours per 4 hours and the aeration intensity was 1L/h,four different flow rates of 0,0.5 m/s,1 m/s and 2m/s were selected to explore the influence of velocity of flow on the removal effect of pollutants by ecological floating bed.The results showed that the higher the flow rate was,the worse the removal effect of pollutants in sewage was.Under the condition of flowing water,the ecological floating bed had a better purification effect when the flow rate is 0.5m/s,and the maximum removal rates of COD,NH4⁺-N,TN and TP were 85%,98%,84.5%and 74%.When the ecological floating bed was in still water condition,in other words,when the flow rate was 0,the maximum removal rates of COD,NH4+-N,TN and TP were 86.5%,98%,89.6%and 78%.It could be found that the treatment effect of ecological floating bed on raw water in still water was better than that of water in flowing state.