| Sewage interception well is an important structures in combined sewer system,through the Main interception of sewage pipes intercept the sunny sewage and rainwater which is at the beginning of the rain, as far as possible the interception sewage flow into the sewage treatment plant, to prevent the occurrence of overflow that can polluted the surface water,and made the flow is more stable in sewage interception.Given this,in order to solve the runoff pollution problems due to flooding caused by rain interception wells in Shanghai Chongming Dongtan area, improve surface water quality,thus promoting the Dongtan Ecoenvironment,sustainable economic development,to carry out the research of the automatic limiting valve technology with a vortex valve has important significance. The article is based on the on the basis of studies for the control of nonpoint source pollution that is caused by initial rain at home and abroad,regarding Chongming Dongtan Eco-City area as the research object,did the research of rainfall patterns and simulated runoff, analyzed the change in conductivity of the sewage and rain water and studied the changes in pollutant concentrations, given the performance characteristics of vortex valve and the maximum number of trapped under different installation angle in the run, analyzed the vortex valve intercept effect,which for improving the river pollution in Chongming Dongtan area has a very important theoretical and practical guidance. The main contents and results of this study mainly includes:(1) Collected to sort out areas of information and current situation regarding water quality in Chongming,analyzed definition, sources, characteristics and and other influencing factors of urban runoff pollution,and discussed the current research status of urban runoff pollution at home and abroad, proposed limiting automatic interception technology for combined sewer system overflow problems in Shanghai Chongming Dongtan area.(2) The study of annual rainfall patterns of Chongming Dongtan regional showed: the average annual rainfall is 1100 mm, the linear regression constant tendency estimate a regression coefficient b and rainfall of x and t the value of the linear correlation coefficient r, namely : a= 37274.93,b =-18.03, the correlation coefficient r =-0.41. Mann-Kendall method test statistic curve shows the mutation point in 2005, the results made conclusion that: the annual rainfall has been a decreasing trend in time.2000 and 2005 showed a more rapid pace of decline in rainfall,increased slowly in 2005 and 2013.(3) The analysis of Shanghai Chongming Dongtan time characteristics of rainfall showed:①rainfall time mainly concentrated in the February-September period,accounting for 79.57% of annual rainfall,where the maximum rainfall from June to August, accounting for 41.10% of annual rainfall.②Temporal distribution of rainfall from last year,June to August of last maximum rainfall.③The maximum annual rainfall events minimal rainfall and rainfall statistics, derived the maximum rainfall intensity range of 121.91-362.39(L/s)/hm2,the minimum rainfall intensity range is 2.23-23.38(L /s) / hm2.④From the point of view of short duration rainfall characteristics,through the maximum rainfall 1,5,10,30,60 min short duration statistical results,the range of variation were 1-4,1.7-8.9,4.3-17.9,15-40.9,21.9-63.2 mm.⑤In the storm characteristics analysis,11 a rainstorm average number of rainy days is 4, the year when most of the rain and moderate rain,storm occurrence frequency of 1 year return;the average storm intensity is 71.18 mm/d,and showed a slow decreasing trend,June-August torrential rain days more heavy rains for several days in June in which up to 12 d,7 and August days of torrential rain also reached 9,the results made conclusion that: rainfall and rainfall duration mainly concentrated in the February-September period,the maximum rainfall intensity of rainfall in initial rain,with the increase of rainfall time,rainfall intensity decreases,increasing rainfall.(4) the use of stormwater management model SWMM simulate runoff of Chongming Dongtan catchment area,studied the rainfall frequency and the catchment areas on the effects of the runoff, the results made conclusion that rainfall time sustained 2h which reached peak flow,for the same sub-region,the catchment area larger,the runoff greater, the design frequency larger, the runoff greater.(5) Made the vortex valve as the main equipment do the vortex valve import and export impact of pressure on the interception,and the mounting angle do the effect on interception and pressure of the vortex valve import and export.it showed that the mounting angle of 11,30,45,60°, the maximum interception was 5.23,7.11,8.91,8.21 L/s,corresponding to the pressure difference respectively 1.5,4.64,6.48,6.56 m,the results made conclusion that the greater the interception,interception optimum state,ie,for the guidance of the vortex valve actually install the application is of great significance.(6) Monitored the vortex valve import and export pressure and interception which installed in sewage interception well.compared them with that data on the vortex valve curve that made by pilot plant test.it showed that error range of 1.11%-8.68%,the results made conclusion that the vortex valve curve work performance is good,to meet the needs of the project.(7) Intercept wells rain water monitoring data show that the conductivity value is large, the basic change between 4500-6000 μs?cm-1,the conductivity decreases after rainfall,the change between 1200-1800 μs?cm-1, the results made conclusion that:rainfall increase and dilutes water concertration the conductivity,at the same time reach the vortex valve in an out of the gate maximum differential pressure,flow quantity of maximum intercept,make its present state of throttling,which has effect on the interception of pollutants. |
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