北京市中心城区某沥青屋面和金属屋面径流污染特征

Characteristics of Runoff Pollution in Asphalt Roof and Metal Roof in Downtown Beijing

为评价不同类型屋面径流污染特征,通过2016~2018年雨季期间对北京中心城区某沥青屋面和金属屋面径流进行监测,分析其径流污染特征,并评价初期雨水弃流对径流污染的控制效果。研究结果表明,沥青屋面径流和金属屋面径流中化学需氧量(COD)、总磷(TP)和氨氮(NH+4-N)的事件平均浓度(EMC)均远高于《地表水环境标准》中Ⅴ类水的水质标准,总体略高于同类型屋面径流的相关研究报道;研究监测的6场降雨事件,沥青屋面径流中悬浮固体(SS)、COD、TP和NH+4-N的初期冲刷强度均高于金属屋面,在前期晴天数较高或降雨强度和降雨量较大时更为显著;通过提出的径流厚度和污染物排放率关系曲线方法,可定量评价不同初期弃流量对径流污染控制效果,金属屋面和沥青屋面径流弃流3mm径流厚度后,可以有效控制(72.75±20.96)%和(80.55±15.94)%的SS污染负荷,以及(66.91±21.68)%和(85.25±11.28)%的COD污染负荷,弃流后径流污染控制效果较好;但按照3mm径流厚度弃流后,仍不能一定保证弃流后径流中SS和COD浓度在国家相关规范要求的初期弃流后雨水径流污染物浓度范围内。

In order to evaluate the characteristics of different types of roof runoff pollution,an asphalt roof and a metal roof runoff in downtown Beijing were monitored during the rainy season from 2016 to 2018,and the runoff pollution characteristics were analyzed.The effect of first flush divider on runoff pollution control was evaluated.The results show that the event mean concentration(EMC)of chemical oxygen demand(COD),total phosphorus(TP)and ammonia nitrogen(NH+4-N)in asphalt roof runoff and metal roof runoff are much higher than the water quality standards of ClassⅤwater in the surface water environment standard,which is slightly higher than the related type of roof runoff in previous researches.For the six rainfall events monitored,the first flush of suspended solid(SS),COD,TP and NH+4-N in asphalt roof runoff is higher than that of metal roofing,and it is much significant when the antecedent dry period is high or the rainfall intensity and rainfall are large.Through the relationship between runoff depth and pollutant discharge rate curve method proposed in this study,the effect of first flush divider was assessed.The(72.75±20.96)%and(80.55±15.94)%of SS pollution load,and(66.91±21.68)%and(85.25±11.28)%of COD pollution load can be effectively controlled,when 3 mm runoff depth was divided for the metal roof and asphalt roof runoff.But after 3 mm runoff depth divided,it cannot be guaranteed the SS and COD in the runoff after first flush divided meet requirements of the concentration regulated in related national code.