The Experiment And Research On The Water Purification Of Hengyang West Lake Park By The Ecological Floating Island Technology

In this paper,from May to June in 2014, with the characteristics of hengyang city climate and plant growth, Canna indica,Cyperus alternifolius and Ipomoea aquatica as water plants that are of landscape ornamental and economic value,were selected to be cultivated under the same conditions of the sample water from West Lake Park of Hengyang,by using the ecological floating island technology..Through regular monitoring air and water temperature,as well as pH,DO,TN,TP and COD in the test water,to quantitatively analyzethe relation and cause between the growth of the three plantsand the change of the nutrient concentration of the pollution index of TN,TP and COD and DO, to compare their different purification effect to water,the most suitable cultivated plants for West Lake Park were electedfrom high purification ability,ecological landscape ornamental value,high survival rate and low cost, which provide a reference for the ecological floating island cultivation technique and plant selection to purify waters in Hengyang other areas.This main results of the experiment areas follows:1.The three plants are able to adapt to the test water and grow better.In the static experiments, the three plants grew normaly in the test water and tillerednew plants,especially their root grew faster. The root changes of Canna indicaand Ipomoea aquatica were most obvious, which roots crisscross formed as a whole. At the beginning of the test, plants grew better because of abundant water and faster, while in late period of the test, due to the lack of nutrient in the water and the reduction of the content of DO and so on, the three plants were subject to certain inhibition.2.The concentration change of the pollution index of TN,TP and COD and DO in the test water is closely related to the growth of cultivated plants. At the beginning of the test, the concentration of CO TN,TP and COD decreased rapidly with the rapid growth of plants; while in late period of the test, due to the influence of the reduction of nutrient salt and the content of DO, the plant metabolism activity became slowly, the removal rate of plants to TN,TP or COD and the pH of the water showed a slowly decreasing trend.3.The net removal rates of nutrient salt of the three plants in water were analyzed,from which the conclusion is that the net removal rate of Ipomoea aquatica to TN is thehighest, that of Cyperus alternifolius the second,and that of Canna indica the lowest. Compared with the removal effect on TP,that of Ipomoea aquatica is the best, thatof Canna indica the second and that of Cyperus alternifolius the worst.Compared with theremoval effect on COD,that of Canna indica is the best, that of Cyperus alternifolius the second and that of Ipomoea aquatica the worst.From the experimental results, the three plants have varying degrees of good effect on removal of TN,TP and COD in the test water; with low prices, short time, fastscene forming, manpower saving and beautiful appearance, which can be planted with collocation to purify the water quality in West Lake by the ecological floating island technology.