南宁市道路初期雨水径流污染物浓度分析

初期雨水污染是雨水径流污染的主要贡献者,掌握初期雨水的污染特征,对于城市雨水处理设施建设尤为重要。以南宁市为例,开展了城市初期雨水径流污染特性分析,旨在为南宁市海绵城市建设以及雨水处理措施提供参考。选取6个采样点的8场降雨,对常规水质指标(COD、NH3-N、TN、TP、SS)进行分析,揭示了降雨过程中污染物的瞬时浓度分布。结果表明:建成区污染物浓度范围和污染物平均水平均明显高于规划区;不同雨型下,雨水初期冲刷效果强弱顺序为暴雨>大雨>中雨>小雨;除小雨外,其他雨型在降雨20 min左右时污染物浓度达到平衡;暴雨情况下,污染物浓度在5 min内降低50%,15 min内70%~80%的污染物随雨水直排或进入城市管网。

ANALYSIS OF POLLUTANTS CONCENTRATION OF INITIAL RAINWATER IN NANNING ROADS

The pollution of initial rainwater is the main contributor to rainwater runoff pollution.It is necessary to master the characteristics of the initial rainwater pollution for urban stormwater treatment facilities.In this subject,take Nanning for example,we carried out the characteristics analysis on initial urban stormwater runoff pollution,aiming to provide a theoretical basis for Nanning sponge city construction and rainwater treatment.In this paper,six sampling points were selected,and the conventional water quality indexes (COD,NH3-N,TN,TP and SS) were analyzed.The results showed that:The instantaneous concentration distribution of pollutants in the process of rainfall was revealed;the pollutants concentration and the average level of pollutants in the built-up area were significantly higher than the planning area;the efficency squence of first flush of different rain pattern was as follows:rainstrom ＞ heavy rain ＞ moderate rain ＞ sprinkle;except the sprinkle,the pollutants concentration of the other rain patterns reached the equilibrium in the 20mins;in the rainstrom,the concentration of pollutants was reduced by 50％ in 5 minutes,and 70％ ～ 80％ of that went straight into the urban pipe network with rainwater in 15 minutes.