Experimental Research On Artificial Floating Island Remediation Technology In Eutrophic Waters

In this review, the classification, composition and purification mechanism of artificial floating island are introduced. Researches in foreign and domestic floating island are described from the development history of artificial floating island. Based on foreign and domestic researches of artificial floating island on water restoration, mixed substrates and mixed plants of combined artificial floating island are chosen to study. First, isothermal adsorption experiment and batch test of single substrates are carried out, on the basis of it, the optimiaztion of mixed substrates experiment is conducted. Then, two plants (iris and canna) of different mixing ratio is optimized in static test. Finally, the hydraulic retention time is optimized in dynamic test, and the restoration effect of different degree of eutrophication is studied, a reference for the practical application of artificial floating island is provided.For the selection of different substrates, the adsorption characteristics on nitrogen and phosphorous of zeolite, haydite, tire crumb, volcanic and vermiculite are initially identified through the isothermal adsorption experiment and batch test. Based on it, haydite and volcanic are chosed as basic substrates, three other substrates are added to optimizing mixed substrates. The result showed No.2 mixed substrates (haydite 50%, volcanic 25%, zeolite 25%) is better on nitrogen adsorption, No.6 mixed substrates (volcanic 25%, zeolite 25%, tire crumb 25%, vermiculite 25%) is better on phosphorus adsorption, No.7 mixed substrates (haydite 20%, volcanic 20%, zeolite 40%, tire crumb 20%) is the optimum mixed substrates on nitrogen and phosphorus adsorption.In static test, the three kinds of mixed substrates are used in artificial floating island. Since a large number of experiments show that the effect of water restoration of mixed plants are better, this paper study different mixing ratio of plants (iris:canna=3:1; iris: canna=1:1; iris:canna=1:3) on restoring eutrophic water. It is showed the removal rate of water nutrients (TN、NH3-N、NO3-N、TP、OP、CODMn) is highest when mixed plant is iris:canna=3:1.In actual treatment of eutrophic water, the impact of HRT on nutrient removal is large, so the optimized test of HRT is studied first in dynamic test. The removal effect of nutrients of combined artificial floating island (with mixed substrates and mixed plants) at different hydraulic retention time (Id,3d,5d,7d,9d) is analyzed, and the best HRT is 5-7d. Then, under the optimal HRT, the restoration of different concentration of eutrophic water bodies by artificial floating island is studied.