| With the development of urbanization, city underlying surface has changed deeply, the reduction of rainfall infiltration, the outbreak of city non-point pollution, the reduction of urban groundwater recharge.In this research, the author did lots of experiments about rainfall from April 2015 to January 2016 to study the underlying runoff characteristics in Yixing. Chemical oxygen demand (COD), suspended soils (SS), ammoniacal nitrogen (NH3-N), nitrate nitrogen (NO3-N), total nitrogen (TN) and total phosphorus (TP) in runoff were monitored. The real-time monitoring showed that the water quality in road runoff and roof runoff were worse than natural rainfall and green runoff in Yixing.CODMn, SS, TN were main pollutants of road runoff and roof runoff, the highest monthly mean concentrations in road runoff were 22.08 mg/L,311.56mg/L,8.13mg/L, respectively. The highest monthly mean concentrations in roof runoff were 23.87mg/L,202.52mg/L,9.51mg/L, respectively. With the accumulation of drought days, the concentration of pollutants changed regularity. Especially, the concentration of nitrogen pollutants was periodical changing. As the accumulation of drought days to 7-12, the concentration of SS in road runoff had extremely significant linear relation with TP in road runoff, and the correlation coefficient was 0.9. The results of roof simulated rainfall runoff showed that pollutant concentration changed along with different roof material, felted roof> tile roof> concrete roof.Basing on the analysis of water quality in rainfall runoff, the author designed rainwater ecological treatment and collection integrated device. The layer of rainwater ecological treatment and collection integrated device was modified by static experiment. The modified slow infiltration system consisted 50cm soil layer,25cm zeolite layer and 20cm stormwater module. The surface loading rate of the infiltration system was 0.76m/d. The field experimental results showed that:when concentrations of CODMn, NH3-N, TN, TP in influent were 30-35mg/L,7-8mg/L,18-20mg/L,0.4-0.5mg/L, respectively, The effluent were 3.92 mg/L,0.52 mg/L,7.56 mg/L,0.18 mg/L. The concentrations of CODMn, NH3-N, TP met the III level of the surface water environmental quality standard (GB3838-2002).In the research, the reconstruction project of green belt beside road in ZhouMucun was designed. The green belt was rebuilt as sunken lawn which could give service for road area at 981 square meters under 36.6mm raininess. |
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