分流制系统泵站放江污染特征研究

摘要:

本研究以上海市中心城区的4个分流制排水系统为研究对象,以COD、NH₃-N及SS为主要指标,研究各排水系统在大雨、中雨及小雨时的泵站放江污染特点及初期效应。结果表明,4个排水系统泵站放江时污染物浓度严重超标。小雨时,放江浓度与旱天生活污水浓度接近,大雨、中雨时受管道中旱天沉积物冲刷效应影响,COD及SS浓度增加,受稀释效应影响,NH₃-N浓度降低。通过分析,发现4个排水系统雨天泵站放江初期效应不明显,上述现象与放江时管蓄污水的排放以及管道沉积污染物的冲刷排放两者效应的共同作用有关,小雨时以前者为主,大雨时以后者为主,中雨时则与两种作用均有关系。本研究揭示了市政泵站雨天排放特征及其影响机制,可用以支撑制定上海市分流制排水系统泵站雨天放江污染控制策略。

Abstract:

This study takes four separate systems in the central area of Shanghai as the research object, and takes COD, NH₃-N and SS as the main indicators to study the pollution characteristics and the first flush strength of pumping station discharge in heavy rain, moderate rain and light rain. The results show that the discharge pollutant concentration of pumping stations of the four separate systems seriously exceeds the standard. In case of light rain, the concentration of discharge is close to that of domestic sewage in dry days. In case of heavy rain and moderate rain, the concentration of COD and SS increases due to the scouring effect of sediments in dry days in the pipeline, and the concentration of NH₃-N decreases due to the dilution effect. Through the analysis, it is found that the first flush of pumping station drainage in rainy days of the four drainage systems is not obvious. That is related to the combined action of the discharge of pipe storage sewage and the scouring discharge of pipeline sedimentary pollutants. The former is mainly in light rain, the latter is mainly in heavy rain, and both effects are related in moderate rain. This study reveals the emission characteristics and impact mechanism of municipal pumping stations discharge in rainy days, which can be used to support pollution control strategy for pumping stations discharge in the separate system of Shanghai.