Zhang Wei, Zhong Xing, Che Wu
Beijing Engineering Research Center of Sustainable Urban Sewage System Construction and Risk Control, Beijing University of Civil Engineering and Architecture, Beijing 100044, China E-mail:
Water Sci Technol. 2018 Feb;77(3-4):1007-1014. doi: 10.2166/wst.2017.622.
To investigate nutrient leaching from extensive green roofs, green roof platforms were established to investigate the effluent quantity and quality during artificial rainfall. When the influent volume reached three times the empty bed volume, for which the cumulative rainfall was around 300 mm, the effluent TP and COD concentrations of green roof platforms filled with peat soil did not tend to stabilize. For a long-term operation, the substrate depths had little significant influence on TN, TP and COD concentrations of the green roof effluents. A normalized cumulative emission process method was proposed to discuss the difference in various pollutant leaching processes. Obvious differences in the leaching process of different contaminants for green roof platforms filled with various substrates were observed. For the green roof filled with modified substrates, the nitrogen and phosphorus pollutant leaching rates were relatively high in the initial stage of green roof operation and the phosphorus leaching rate was higher than that of nitrogen. The green roof is a sink for TN, but not for TP and COD in this study. The outcomes are critical for the selection of green roof substrates and also contribute to green roof maintenance.
为了研究粗放式绿色屋顶的养分淋失情况，搭建了绿色屋顶平台以研究人工降雨期间的出水水量和水质。当进水体积达到空床体积的三倍时，此时累计降雨量约为300毫米，填充泥炭土的绿色屋顶平台的出水总磷（TP）和化学需氧量（COD）浓度并未趋于稳定。对于长期运行而言，基质深度对绿色屋顶出水的总氮（TN）、总磷和化学需氧量浓度影响不大。提出了一种归一化累积排放过程方法来探讨各种污染物淋失过程的差异。观察到填充不同基质的绿色屋顶平台在不同污染物淋失过程中存在明显差异。对于填充改良基质的绿色屋顶，在绿色屋顶运行初期，氮和磷污染物的淋失率相对较高，且磷的淋失率高于氮。在本研究中，绿色屋顶是总氮的汇，但不是总磷和化学需氧量的汇。这些结果对于绿色屋顶基质的选择至关重要，也有助于绿色屋顶的维护。
