为研究温州降雨径流污染情况,监测了温州2个采样区4场较为典型的降雨过程,测定了不同下垫面径流中BOD5和COD的浓度,并且计算出污染物的EMC值、M(V)曲线和BOD5/COD值等.结果表明,温州城市降雨径流中BOD5和COD的含量分别介于ND~69.21 mg.L-1和ND~636 mg.L-1之间,不同城市下垫面径流中BOD5和COD的含量均随着降雨历时的延长而呈下降趋势,处理初期径流水样对减少耗氧性有机污染具有重要意义.从COD和BOD5的EMC值来判断,部分城市下垫面降雨径流中污染物浓度超出地表五类水标准,甚至高于污水排放二级标准,此类降雨径流若直接入河将对下级受纳水体造成耗氧性有机污染的压力.根据M(V)累积曲线判断,COD初期冲刷效应在城市降雨径流中是较为普遍的,城市降雨径流中的BOD5表现出与COD类似的初始冲刷情况,该结果亦表明径流初期耗氧性有机污染严重.城市降雨径流中COD和BOD5的浓度受下垫面类型和降雨条件的影响,而BOD5/COD指标的变化特征则指出生物降解是削减有机污染负荷的有效途径之一,但不同下垫面径流有机污染的治理工作应采用不同的最佳管理方案(BMPs).
Four typical rainfalls were monitored in two different research areas of Wenzhou Municipality.Concentrations of BOD5 and COD in six different urban runoffs were measured.In addition the event mean concentration(EMC)、 M(V) curve and BOD5/COD of pollutant were calculated.The results showed that concentrations of BOD5 and COD in different urban runoffs of Wenzhou ranged from ND to 69.21 mg·L-1 and ND to 636 mg·L-1.Concentrations of BOD5 and COD in different urban runoffs were decreasing over time,so it is greatly significant to manage the initial runoff for reducing organic pollution.Judged by EMC of BOD5 and COD in these five rainfalls,concentrations of pollutant in some urban runoffs were out of the integrated wastewater discharge standard.If these runoffs flowed into river,it would cause environmental pressure to the next level receiving water bodies.According to the M(V) curve,the first flush effect of COD in most urban runoffs was common;while the first flush effect of BOD5 was same as that of COD.The result also showed that organic pollution was serious at the beginning of runoff.The underlying surface type could affect the concentration of BOD5 and COD in urban runoff.While the results of BOD5/COD also suggested that biodegradation was considered as one of the effective ways to decrease the pollution load of organics in urban runoff,and the best management plans(BMPs) should be selected for various urban runoff types for the treatment of organic pollution.