| Dragon-shaped Water System, DSWS, is an artificial landscape lake in Beijing Olympic Park. Based on the inspection and measurement of the water quality of DSWS, the water quality did not meet the design standards, and TN&TP concentrations exceeded the standards. The results of eutrophication assessment showed that the frequency of number TLI<50accounted30%to the total. Frequency of number50<TLI<60accounted55%, and the water was light eutropher. Frequency of number60<TLI<70accounted15%, and the water was middle eutropher. In DSWS, TLI value of above50about eutrophication assessment number proportion was70%, and the eutrophication proportion is70%.The research results showed that reclaimed water was the main pollution source, and the inputed pollutant amount accounted for more than63%of the total. The internal pollution of sediment was studied, and the results showed that the content of nitrogen&phosphorus in sediment was in high level. The release amount of N&P from the sediment was much affected by the conditions of different hydrodynamics, overlying water temperature and aeration.To facilitate the management and eutrophication cause analysis of DSWS, WASP was successfully used to simulate the water quality, and reasonable model parameters were found by simulating. The absolute error value of TN simulation was0.80mg/L, and the average relative error was25.7%. The average absolute error of TP simulation was0.05mg/L, and the average relative error was41.0%.Results of studying on effects of hydrophytes on removal of pollutant showed that Cyperus alternifolius, Lythrum salicaria, Acorus calamus, Vallisnerias Piralis, and Myriophyllum verticillatum were suitable to grow in reclaimed water environment of DSWS and had preferably effect on removing nitrogen and phosphorus. The removal rate of TN was between2.5%～2.5%, and the removal rate of TP was between46%～97%.According to the above research results, technologies of DSWS water quality restoration and conservation were proposed:firstly, to control the pollution sources of input, and to improve the recycled water water quality, and strictly monitor the release of endogenous pollution; secondly, to establish a reasonable and harmonious ecological restoration system; thirdly, to strengthen water circulating and to promote water self-purification; fourthly, to improve the quality management system. By utilizing a comprehensive programming and implements of multiple methods of water treatment technology, the goal of eutrophication control and water quality improvement will be achieved. |
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