不同介质组成的粗放型绿色屋面降雨出流水质

构建5个绿色屋面中试设施,考察不同介质组成的设施在实际降雨条件下出水水质状况并与降雨、沥青屋面径流、空白对照设施出水水质进行对比.结果表明,常用屋顶绿化复合介质设施的出流中,TP,NH4+-N和COD的平均质量浓度分别达到0.95,1.66,115mg·L-1,高于沥青屋面径流和空白对照设施的出水水质,使用无机复合介质和废弃物利用介质的设施出水水质优于对照屋面;从出水污染物质量负荷角度分析,使用上述3种类型介质的绿色屋面设施都不是TN,TP,TSS和COD的污染源,并能够减少雨水带来的NH4+-N负荷;绿色屋面设施植被层生长状况和出水中营养物质浓度呈现相关性,长势较好的设施出流中营养物质浓度较高;介质中添加给水厂污泥能够有效控制介质层P的淋失且不影响植物生长.

Effluent Quality of Extensive Green Roofs with Different Substrates

Effluent qualities of pilot scale green roof facilities with different substrate compositions were evaluated and compared with runoff qualities of an asphalt roofing, the blank control roof and rain water for total 20 rainfall events. The results show that the concentration of TP, NH4+ N and COD in effluent of the facility using commercial green roof medium are 0.95, 1.66 and 115 mg·L-1, respectively, which are higher than those of runoff from asphalt roofing and control facility effluent. The effluent quality of the experiment facility using light inorganic medium and the cheap medium made of brick scrap and sand are better than the effluent of control facility. Considering runoff volume reduction effect, the pollution loads of different green roof facilities are not pollution source for every monitored pollutant compared with the load of asphalt roof and control facility, for NH4+ N load the green roof facilities can even reduce the load of rain water. The aboveground biomass of green roof is positively related to the effluent quality, and the facility using commercial green roof medium presents a better growth status than those using media emphasizing effluent water quality. Application of water treatment residual as component of the medium, the leaching of P from commercial green roof medium is significantly reduced and the growth of vegetation is not affected.