Study On Vegetation Revement In Treating Runoff Pollutant Of Suzhou Ancient City

With the help of the integrated demonstrational project of the improvement of the aquatic environment quality in Suzhou, the treatment of pollutants caused by runoff flow was studied by the plant revetment, according to the water quality characteristics of overland flow in the ancient city. The contents of the study were included: the confirmation of water quality used in the simulation experiment by the investigation to the pollution characteristics of overland flow in the ancient city; the filtration of revetment plants by the comparison of water resistance and purifying effect between different lawn plants; the filtration of revetment configurations by comparing three groups of captive and dynamic tests in the revetment simulation tanks. Conclusions were summarized as follows:(1) The pollution of overland flow in the ancient city was serious, and the concentration of organic substance, nitrogen and phosphor was much more than that of the surface water quality standards. The concentration of pollutants caused by runoff flow had the obviously changing rules with the extending of rainfall. The concentration of pollutants caused by initial runoff flow was very high, and with the prolonging of rainfall, the concentration began to slide and leveled off. So collection and treatment of initial runoff flow (runoff flow of preceding 30 min) was the most economic and effective method to control the pollution of overland flow.(2) The adaptability to wastewater and the purifying effect of Festuca arundinacea were better than other plants used in the experiment. When the quality of stimulation water was CODMn 10.85 mg/L, TN8.92mg/L, NH3-N 5.49mg/L, TP 0.56mg/L, the rate of removal in the experiment using Festuca arundinacea would reach 73.1 % , 93.2 %, 95.4% and 94.6% respectively.(3) During the dynamic tests in the revetment simulation tanks, the average removal rate of influent pollutants in the simulation tanks with up and down clapboards was higher than that in the simulation tanks without clapboards and with left and right clapboards, and the tolerance of impulsion load of the former was higher than the two other.In the area of city river network with more people and less land, overland flow can be treated and the effect of the virescence landscape was reinforced by the application of the new plant revetment. And it had extensive application outlook.