| To establish Urban non-point source pollution closure system in Eastern Lake Dianchi basin,the standardized Efficient Interceptor and control system was developed and standardized,which using TN as the interception target,electric conductivity as rapid display indicator. Both the hydrologic and hydraulic factors were investigated on the impacts of interception efficiency. And closure Radius model was built to find out the service area and optimal position of the Efficient Interceptor in a certain area. The 15 years(from 1995 to 2009)simulated results of Chenggong model have been extracted for statistical analysis to figure out a coordinated efficient closure control system in a certain area. And time control and concentration control methods were designed and compared to determine a better control method.According to previous research results, the Efficient Interceptor was developed and normalized successfully. The Efficient Interceptor includes initiative interceptor and passive interceptor. The initiative interceptor is made up of 3 units:(1)detection unit, including conductivity detecting probe ? runner ? stainless steel Olivier;(2) data collection and instruction unit, including conductivity meter ? signal transmitting/receiving equipment and industrial computer;(3)perform unit, including cast iron gate and flashlight dual-use hoist. The passive interceptor get rid of the detection unit.Both the hydrologic and hydraulic factors were investigated on the impacts of interception efficiency, including area, impermeability, land usage, slope, conduit gradient, rainfall duration, reappearing period, peak coefficient. Results indicates that : The sequence of impact on SS interception efficiency is reappearing period, rainfall duration, peak coefficient, impermeability, land usage, conduit gradient, area, slope; for COD, the sequence is reappearing period, peak coefficient, rainfall duration, impermeability, land usage, conduit gradient, slope, area; for TN, impermeability, reappearing period, conduit gradient, rainfall duration, peak coefficient, slope, area, land usage; when it comes to TP, the sequence turns to be impermeability, land usage, peak coefficient, reappearing period, conduit gradient, rainfall duration, slope, area.The closure efficiency of different conduit lengths and service areas in typical urban area was investigated. Results shows:(1)the efficiency of various closure radius is effected by closure ratio. When closure ratio is before the critical value, the closure efficiency is high along with a high closure ratio, otherwise, the trend is opposite. The critical value of SS?COD?TN?TP are 25%?30%?25%?25%. And the cause for this phenomenon is that concentration and water quantity play a major part alternately.(2)When the closure ratio is 50%, the closure efficiency is high along with a short closure radius. While the closure radius among 1 to 3 km, closure efficiency of SS?COD?TN?TP decrease dramatically along with closure radius. 3km or longer closure radius, the closure efficiency changes gently. Considering the pollutant closure effect and engineering economy, the SS?COD?TN?TP maximum values of closure radius should be 3km ? 3km ? 2.5km ? 2.6km.(3) The instantaneous load curve presents “upper convex—down concave” pattern, which accounts for the “sharp decrease—slow change” of closure efficiency in various closure radius.The closing times and TN values of 3rd discharge outlet of closing time of 12 discharge outlets in 291 rainfalls(from 1995 to 2009)have been extracted and for statistical analysis. According to the results, time control and concentration control were raised to solve the interception system in a certain urban basin. These two methods were compared from the aspects of closure efficiency and pollutant concentration of closure quantity. It shows out that concentration control method is superior to time control method. Hence, for getting a high closure efficiency, concentration control method is advised to apply in urban runoff closure system. |
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