合流制排水系统降雨径流污染物的特性及来源

Characterization of storm-water pollutant sources in a combined sewer network

在昆明市典型合流制排水小区对降雨径流进出水水量、水质进行了研究,旨在揭示城市区域合流制排水系统中降雨径流不同来源的污染物特性及各个污染源的比例.分别监测了合流制排水系统日常污水以及4场降雨期间小区出口断面、街道、屋顶、庭院降雨径流的水量、水质.结果表明,人为干扰是影响城市径流污染物输出强度的主要因素,城市下垫面降雨径流污染物输出浓度顺序为:道路>庭院>屋顶,道路是城市面源污染的关键源区;道路次降雨径流量约25%,却产出了40%～80%的污染物,而屋顶次降雨径流量约50%,却仅有4%～30%的污染物负荷.合流制排水系统中管道沉积物在降雨期间的迁移是重要的污染源,4场降雨中管道沉积物的TN、TP、SS、COD和BOD5的污染贡献率在30%以上.降雨强度是影响管道沉积物输出的重要因素,在高强度降雨下,管道沉积物污染贡献率高50%以上.在不同的降雨特性条件下,合流制排水系统主导污染源有所不同.

The flux and quality of wet weather flows from the entry to the exit of the typical combined sewer network in Kunming was measured, aiming to follow up the quality of the runoff in the sewer network and the contribution of different sources to the pollution in the runoff. Rain events were measured on roads, roofs and yards of the catehment, as welt as in dry and wet weather flows at the catchment outlet. The results showed that artificial disturbance is the main factor which influences the concentration of the urban runoff. Among the main urban ground surfaee types, the order of runoff pollutant concentration is： road 〉 yard 〉 roof. Roads are the key source of the pollution in urban runoff. In the study area, road runoff, which generates about 25% of the total runoff volume, represents more than 40% - 80% of the total runoff pollution mass. Roof runoff, whieh generates about 50% of the total runoff volume, represents only 4% - 30% of the total runoff pollution mass. The erosion of in-sewer sediment is an important source of pollution during wet weather flows through the combined sewers. For the four rains measured, more than 30% of the total TN, TP, SS, COD and BOD5 loads originated from the in-sewer sediments. Maximum rain intensity is an important factor＂ which influences the erosion of the in-sewer sediment. For the high rain intensity, the contribution of the in-sewer sediment to the total pollution mass is more than 50%. For rainfalls of different character, the dominant source contributing to the wet weather flows differs.