基于SWMM模型的合流制管道溢流污染控制系统模拟

Simulation of combined sewer overflows pollution control system based on SWMM

针对合流制管网污水溢流所导致的城市内涝和城市内河黑臭问题,以武汉市巡司河片区为例,利用暴雨洪水管理模型(storm water management model,SWMM)软件,构建该地区合流制排水系统的水力水质模型,模拟了不同降雨强度的暴雨模拟和全年降雨状况,分析了该地区溢流污染特征,据此提出了切实有效的合流制排水系统改造方案,并采用SWMM模型对不同改造方案的溢流水量和水质控制效果进行了模拟。结果表明,在箱涵与雨水调蓄池的共同作用下,对溢流污水量的截流比例在90%以上,年溢流次数小于10次,年溢流水量平均减少了1.75×10^7 m^3,对污染物的截流比例均在95%以上,每年溢流进入地表水中的COD减少了3 295.5 t,NH3-N减少了505.8 t,TP减少了63.1 t,SS减少了1 981.1 t,溢流问题得到了极大的缓解,溢流污染能够得到较好的控制。随着暴雨重现期延长,截流效果会随之下降。箱涵和雨水调蓄池的组合措施对溢流污水具有明显的削减和调控作用,能够有效降低城市内涝隐患和缓解内河黑臭化问题,通过定量表征箱涵-雨水调蓄池组合在溢流污染方面的控制效果,为国内合流制排水管网改造提供技术支持和海绵城市设计提供参考。

Xunsi river area of Wuhan was taken as an example, aiming at the problems of urban water logging and black and odor problem in the urban inland river caused by sewage overflow in combined sewer network,the storm water management model(SWMM) software was used to establish the hydraulic and water quality model of the combined drainage networks. Both the rainstorm at different rainfall intensities and the annual rainfall were simulated, and the overflow pollution properties in the region were analyzed. The reasonable modification schemes for combined sewer drainage system in Xunsi river basin were proposed, and the overflow water volume and water quality control effects were simulated under different schemes by using of the SWMM.The results showed that under the joint action of culvert and storage tank, the interception ratio of overflow sewage volume was above 90%, the annual overflow times were less than 10, annual overflow water volume reduced by 17.517 million m^3 on average, all the interception ratios of contaminant were above 95%. The COD,NH3-N, TP and SS entering the surface water through overflow dropped by 3 295.5, 505.8, 63.1 and 1 981.1 t every year, respectively. The overflow problem could be greatly alleviated, and the overflow pollution could be well controlled. With the increase of the recurrence period of rainstorm, the interception effect decreased. The combination of culvert and storage tank had significant reduction and control effects on overflow sewage, which could lower the risk of urban water logging and black and odor problem in the urban inland river. Through quantitative characterization of the control effect on overflow pollution by the combination of culvert and storage tank, this study provides a scientific basis for renovation of domestic combined drainage network and sponge city design in China.