Exogenous Pollution Reduction And Ecological Improvement For Southern Urban Landscape Water

Most of the southern urban landscape water is in a gated state with no water in transit in non-flood discharge season. So water is also in the flow of sluggish state, thus leading to low self-purification capacity. At the same time, a certain amount of exogenous pollutants exacerbate the deterioration of water quality、eutrophication and water ecosystem degradation of urban landscape water. This research sets Yangzhou Qujiang lake and its associated river as the research object, and on the basis of its water poullution characteristics and ecological status, independently develops exogenous pollution reduction technology, rebuilds the vegetation along Qujiang lakeside zone and the water ecosystem of Qujiang river and its association and applies all with technology of strengthening biological self-purification function to Yangzhou Qujiang river and its association to improve its water quality.The conclusions of this study are as following:1This study discribed water pollution characteristics of Qujiang river by the way of assessment of nutrition status and factor analysis to grap a comprehensive exposition of water pollution characteristics of Qujiang river. Also, plant diversity index was used to characterize the lakeside plant diversity. Results showed that the trophic state index of most sections was between50to60, so as it could be definted as in a mild state of eutrophication while some other local sections, between60to70, in a moderate state of eutrophication. And the state of eutrophication was developing. The major water pollution factors of the Qujiang river were Organic matter and TP. The plant diversity of the lakeside zone was low whose index is0.45.2The initial rainwater pollutant reduction device had functions of physical entrapment、 biodegradation、adsorption of nitrogen and phosphorus and algae control, and it could effectively reduce COD、TP、TN in point source initial rainwater. Practical results which were based on laboratory tests showed that the removal rates of COD、TP、TN in initial rainwater of a certain period of rainfall (one hour) by the initial rainwater pollutant reduction unit could respectively reach to59.52%、46.02%、27.51%.3Infiltration drainage, along the lakeside, which had the functions of physical interception and biological degradation, can effectively reduce COD、TP、TN in non-point source rainwater. Practical results which were based on laboratory tests showed that the removal rates of COD、 TP、TN in road runoff of a certain period of rainfall (one hour) by infiltration drainage could respectively reach to41.67%、56.25%、16.38%.4The overflowing sewage pollutant reduction device had functions of physical entrapment、biodegradation、adsorption of nitrogen and phosphorus and algae control, and it could effectively reduce COD、TP、TN in overflowing sewage. Practical results which were based on laboratory tests showed that the removal rates of COD、TP、TN in overflowing sewage of a certain period of rainfall (one hour) by overflowing sewage pollutant reduction device could respectively reach to45.89%、32.59%、16.47%.5The imported polluted reduction technology、ecological restoration techniques and technology of strengthening biological self-purification were integrated and applied to Yangzhou Qujiang lake and its association. As technology integration has been running, the water quality of Qujiang lake and its association remains better than IV class(in addition to TP, the maximum value is0.18mg/L); the plant diversity of lakeside zone will increase as the Shannon-Wiener index will increase to1.04; water objectives such as TN、ammonia and chlorophyll-a in floating bed area were significantly reduced compared with that at the reference point.