山地城市降雨初期合流污水污染物时空变化特征

Temporal and Spatial Variation Characteristics of Pollutants in Combined Sewer System during Initial Stage of Rainfall in Mountainous City

选择了三峡库区典型山地城市涪陵,重点考察了各功能区降雨初期合流雨污水中典型污染物的时空变化特征。结果表明:当降雨强度>5 mm/h时,各功能区采样点污水窨井中污染物浓度随时间先增后降,呈单峰变化,污染物浓度出峰时间一致;当降雨强度为1.6 mm/h时,各功能区采样点污水窨井中污染物浓度则呈多峰变化,各污染物浓度出峰时间不一致。当降雨强度分别为11.7、5.6、1.6 mm/h时,污染物浓度出峰时间分别在10、15和20 min以上。车流量大、人口密度高的旧城区(合流制),初期雨污水峰值浓度较高,TSS值均高于1 500 mg/L。由于山地城市管网坡度较大,即便是降雨量<2 mm的降雨,初期合流污水TSS峰值仍高于300 mg/L;初期雨污水中主要污染物与TSS线性拟合度较好。因此,建议对于初期合流溢流雨污水的强化处理措施以TSS为主要污染物进行去除。

Fuling City which is a typical mountainous city in three gorges reservoir region was selected as the research object to investigate the temporal and spatial variation characteristics of typical pollutants in combined sewer system during the initial stage of rainfall in each functional area. The results showed that when the rainfall intensity was more than 5 mm/h, the concentration of pollutants at sampling points in sewage inspection wells of each functional area increased and then decreased with time. The different kinds of pollutants had the same peak appearance time with one peak. When the rainfall intensity was only 1.6 mm/h, the pollutants had different peak appearance times with multiple peaks. When the rainfall intensity was 11.7 mm/h, 5.6 mm/h and 1.6 mm/h, the relevant peak appearance time of pollutants was more than 10 min, 15 min and 20 min, respectively. In the old town with heavy traffic and high population density, the peak concentration of initial combined sewage was high, and TSS was more than 1 500 mg/L. Even if the rainfall was less than 2 mm, TSS was still more than 300 mg/L due to the large slope of pipe network in the mountainous city. There was good linear fitting between major pollu- tants and TSS in the initial combined sewage. So, TSS should be considered as a major pollutant that needed to be removed in the enhanced treatment of the initial combined sewage.