生物滞留设施去除城市道路径流中邻苯二甲酸酯的效果评估

Removal efficiency of phthalates in urban highway runoff in Shanghai by a bioretention system

上海市区道路径流中存在邻苯二甲酸酯(PAEs)污染,平均浓度达到171.71μg·L^(-1),高于欧洲和澳大利亚道路径流浓度近一个数量级,直接排放会对地表水体造成污染.为了从源头控制道路径流中PAEs污染,在上海内环高架道路下建造了应用规模生物滞留设施,研究城市绿色基础设施对道路径流中6种美国EPA优先控制PAEs污染物的控制效果及机理.生物滞留设施表面积为20 m2,汇水面积约为400 m2,底部带有防渗膜,适用于高地下水位地区.结果表明,8场监测降雨事件中,设施出水∑6PAEs平均浓度为10.23μg·L^(-1),显著低于道路径流∑6PAEs平均浓度171.71μg·L^(-1)(p<0.05).沉淀预处理对PAEs无显著去除效果,生物滞留池对DEHP的去除率与TSS的去除率呈显著正相关,主要通过基质层截留作用去除;DEP、DBP、DMP等低分子量PAEs的去除率与设施水力负荷呈负相关,主要通过生物滞留池基质的吸附作用去除.DEHP、DBP为我国《地表水环境控制标准》控制污染物,生物滞留池出水DBP浓度低于标准值3μg·L^(-1),达标率100%;出水DEHP浓度大多情况下低于标准值8μg·L^(-1),达标率为71%,生物滞留设施可以有效控制道路径流PAEs污染.本研究的结果适用于我国东南部地下水位较高的地区,可为绿色基础设施控制地表径流PAEs提供设计理论指导.

Average EMCs of PAEs in runoff from the Shanghai urban road,China,were 171.71 μg·L^（-1）,these being considerably greater than values reported in Europe and Australia. Without suitable management measures,this runoff water will contaminate surface water. To evaluate the removal efficiency and mechanism of PAEs using green infrastructure,a field scale bioretention facility was constructed in the Shanghai urban area. The retention facility had an area of 20 m2,contained a suitable liner to retain the water,and collected runoff from a 400 m2 area of highway. Water samples were collected from the inflow and outflow from the forebay and the bioretention area,respectively. Six priority PAEs and conventional criteria,such as TSS,were analyzed. In the period from the summer to autumn,2017,eight rainfall events which produced obvious outflow were monitored. The average∑6 PAEs in the infiltrated outflow was 10.23 μg·L^（-1）,while ∑6 PAEs in road runoff was 171.71 μg·L^（-1）. The concentrations of PAEs did not decrease significantly due to sedimentation in the forebay,although the forebay did remove TSS. Removal of DEHP was positively correlated with the removal of TSS,indicating that the removal of DEHP depended on eliminating fine particles through substrate infiltration. Higher hydraulic loading rates were associated with the poor removal of low molecular weight（ LMW） PAEs,indicating that removal of LMW PAEs depended on sorption of soil.Concentrations of effluent DBP were lower than 3 μg·L^（-1）,thus adhering to local standards for surface water. Removal rates of DEHP were greater than90%,and the effluent had a 29% probability of exceeding the 8 μg·L^（-1） criterion for surface water. Nevertheless,the over standard rate was no more than1.5. Results indicate that the use of a bioretention system is a promising management practice to eliminate PAEs from urban road runoff. This study contributes to the instruction of the design of green infrastructure for controlling PAEs in urban surface runoff which are suitable for use in areas with a highgroundwater level.