Simulation Analysis of Annual Pollution Load of Combined Sewer Overflow in Wuhan City Based on SWMM

Abstract

With the acceleration of urbanization, the urban water environment problem has become increasingly severe. The combined sewer overflow(CSO) pollution control has become the focus and problem which urgently needed to be solved in China’s sponge city construction and black smelly water treatment. Simulating and calculating the annual pollution load of the CSO is of great significance for the quantitative analysis of the cause of the water environment pollution. In this paper, the improved SWMM model coupled with the module for scouring the silting on the bottom of the pipes was used to simulate the combined sewer system with a drainage area of 1666ha. The results show that under the same drainage area, the larger the interception ratio is, the smaller the annual pollution load of CSO is; under the same interception ratio, the larger the drainage area is, the smaller the annual pollution load of CSO is. For the combined sewer system in Wuhan, the annual COD, TN and TP load of CSO can be calculated by three formulas: WcoD=378.58-33.71lnF, WTN=51.032-5.7871/lnF and WTP=13.667F-0.404, respectively when the interception ratio is equal to 1.0.