| With the accelerated process of urbanization, the area of impermeable zone is increasing, the pollution of urban runoff has become the main reason for water pollution in the city.It is significant that take effective measures to reduce the urban runoff pollution to alleviate the problem of water shortage in cities, reduce the risk of city waterlogging and energy consumption. Now, there is lack of research for mountainous urban runoff pollution control technology in China. Chongqing is a typical mountainous city, Longjing Lake in Chongqing Expo Garden is a typical mountainous lake, the control of Long Jing Lake runoff pollution plays a crucial role in Long Jing Lake water quality protection. The flow and water quality of runoff and each runoff control unit in Chongqing Expo Garden Jiangnan Garden area were monitored and analyzed in this study. Retention and infiltration capacity and pollutants removal efficiency of each unit in Jiangnan Garden were analyzed. Operation and management measures of Jiangnan garden were put forward according to long-term observation results. Permeability coefficient and adsorption capacity of different mixed matrix were analyzed by permeability testing, static adsorption experiment and adsorption kinetics experiment. The law of pollutants removal was analyzed by dynamic adsorption test in the soil column.Indoor simulation test show that the permeability coefficient of the soil and river sand mixing rate for 0:1, 3:7, 5:5, 7:3, 1:0 is: 1.4223×10-4m/s?1.1174×10-4m/s?0.3056×10-4m/s?0.2014×10-4m/s?0.1134×10-4m/s. The static adsorption of nitrogen and phosphorus was in accordance with the Langmuir and Freundlich adsorption isotherm, the maximum adsorption rate of the substrate increases with the increase of the concentration of soil in the substrate. The adsorption of nitrogen and phosphorus by sand is not stable enough, and the incorporation of soil in sand can significantly reduce the risk of nitrogen and phosphorus release from the substrate. Dynamic adsorption test results show that the COD, NH3-N and TN showed decreased with increase of soil depth, whether it is in high concentration or low concentration of influent, soil infiltration system of COD, NH3-N and TN removal is relatively stable, and of NO3-N and TP removal effect is poor.Rainfall data investigation and monitoring shows that the annual precipitation in Chongqing various from 815 mm to 1439 mm, interannual variation is larger, the rainy season in Yubei is from May to August. Characteristics of rainfall and runoff monitoring show that the Jiangnan garden area runoff peak coming faster, runoff pollution concentration is related to the pre drought duration. The different rainfall has the different first flush.The water quantity monitoring of infiltration filter and detention pond system shows that the buffer pool has obvious reduction and delayed effect on the peak of storm water runoff and a significant effect on the runoff discharge. The average infiltration rates of the buffer bools, first and second stages infiltration filter are: 0.158 m/h, 0.132 m/h, 0.112 m/h. For 0.1 years of the rainfall reappearing period, the runoff flow will be all delay and infiltration in the system. For 5 years of the rainfall reappearing period, the runoff flow will be delay and infiltration 33.66% in the system, and the water total residence time is 115.82 min.The water quality monitoring of infiltration filter and detention pond system shows that the average SS removal rate of the system is 29.93%, and the average SS removal load is 28.87×10-4mg/(L·m2), the average COD removal rate of the system is 25.80%, the average COD removal load is 72.29×10-4mg/(L·m2), the effluent COD is 30 mg / L below. At high load influent(TN>1.5mg/L, TP>0.1mg/L), the average TN removal rate of the system is 69.62% and the average TN removal load is 28.87×10-4mg/(L·m2), the average NH3-N removal rate of the system is 63.27% and the average NH3-N removal load is 16.66×10-4mg/(L·m2),the average TP and DP removal rate of the system is 59.65% and 18.83% and the average TP and DP removal load is 2.59×10-4mg/(L·m2) and 1.76×10-4mg/(L·m2). At low load influent(TN<1.5mg/L, TP<0.1mg/L) conditions, the average TN removal rate of the system is 4.40% and the average TN removal load is 0.68×10-4mg/(L·m2), the removal of TP and DP is poor, the average TP and DP removal rate of the system is 25.22% and 4.64% and the average TP and DP removal load is 0.11×10-4mg/(L·m2) and 0.03×10-4mg/(L·m2)?... |
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