高速公路服务区径流污染物在生物滞留填料中的时空降解特性

Spatio-Temporal Degradation Characteristics of Expressway Service AreaRunoff Pollutants in Bioretention Filler Layer

以天然土壤、建筑砂、木屑堆肥、沸石和无烟煤和砾石为填料介质构建了复合填料生物滞留柱;通过人工模拟试验,评价了滞留柱对高速公路服务区地表径流中化学需氧量(COD)、总磷(TP)、氨氮(NH+4-N)及总氮(TN)的净化效果;分析了径流污染物在滞留柱填料层中的时空降解特性。结果表明:复合填料生物滞留柱对径流污染物具有较好的去除效果,在3次进流工况下,生物滞留柱对C COD、C TP、C NH4^+-N及C TN的去除率平均值分别为80.2%、73.3%、91.1%及63.9%;在进水期,COD、TP及NH4^+-N的出流浓度沿填料层深度总体呈下降趋势,而TN的出流浓度则波动性显著;在进流停止后的12~144 h期间,随着时间的延长,C COD在种植土层呈逐渐升高趋势,在砂滤层及砾石层逐渐降低并趋于稳定,C TP在3种填料层中均逐渐降低并趋于稳定,C NH4^+-N在种植土层呈先下降后逐渐升高的趋势,而在砂滤层及砾石层则逐渐降低并趋于稳定,C TN在种植土层及砂滤层中呈先下降后逐渐升高的趋势,而在砾石层则逐渐降低并趋于稳定。

A composite filler bioretention column was constructed by using natural soil,construction sand,sawdust compost,zeolite,anthracite and gravel as packing media.The purification effects of retention column on COD,TP,NH4^+-N and TN in surface runoff of expressway service area were evaluated through artificial simulation test,and the spatio-temporal degradation characteristics of runoff pollutants in the packing layer of retention column were analyzed.The results show that the composite filler bioretention column has a good removal effect on runoff pollutants.The average concentration reduction rates of COD,TP,NH4^+-N and TN by bioretention column under the three inflows condition are 80.2%,73.3%,91.1%and 63.9%,respectively.During the inflow period,the outflow concentration of COD,TP and NH4^+-N decreases along the depth of the filler layer,while the outflow concentration of TN fluctuates significantly.Within 12 to 144 hours after the stopping of inflow,with the time prolonging,the COD concentration gradually increases in the planting soil layer,but gradually decreases and stabilizes in the sand filter layer and gravel layer;the TP concentration gradually decreases and stabilizes in the three kinds of filler layers;the NH4^+-N concentration decreases at first and then gradually increases in the planting soil layer,but gradually decreases and stabilizes in the sand filter layer and gravel layer;the TN concentration decreases at first and then increases gradually in the planting soil layer and sand filter layer,but gradually decreases and stabilizes in gravel layer.