Analysis And Study On The Environment And Economy Benefit Of Intercepting Ratio In Intercepted Combined Trunk Sewer

Intercepting ratio is an important parameter in the rehabilitation of Combined Sewer System (CSS) and plays a decisive role to the environmental benefit,construction investment and operating cost. Therefore, study on this problem has important theory and practical value of engineering in this paper.Relation between intercepting ratio and receiving water shoule be analyzed in order to select rationally the intercepting ratio. At the same time ,study on the relation between them needs calculating quantitatively Combined Sewer System Overflow (CSO) spill volume,time and water quality and study the self-purification of contamination in receiving water. Thus it is very difficult to calculate the spill volume and water quality because they involve many processes such as rainfall, yield runoff of rainfall,flow concentration of surface runoff, ground pollutant build up,washout,the flow concentration of combined drainage system and CSO.First, based on comprehensive analysis on the present study status on intercepting ratio home and abroad, the method used in analyzing the process of rainfall-runoff is adopted to study intercepting ratio in this paper. In order to calculate quantitatively the process of rainfall-runoff, the CSS model of Zhang Cha catchment is developed based on EPA's SWMM(Storm Water Management Model) in this paper.And then calculate CSO spill water quality,spill volume and spill time at different intercepting ratio using the developed SWMM, and analyze the effect on them by intercepting ratio.Second,based on the characteristic of the receiving water studied in this paper,develope a dynamic one-dimension water quality model for NanBei river in Zhangcha town of FoShan city,and develope a program of water quality model based FORTRAN POWERSTATION. And then ,calculate the concentration of CODcr in receiving water using the simulation results of SWMM and analyze the effect on the environment of receiving water by intercepting ratio.At last,The construction investment and operational and administrative expenses of intercepting trunk sewer,pumping station and sewage farm is calculated and the relation between them is discussed.