Heavy metal removal from urban stormwater runoff using bioretention systems

• Main Authors: Shu-Wen Jang, 張舒雯
• Other Authors: 林逸彬
• Format: Others
• Language: en_US
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/4288z4

碩士 === 國立臺灣大學 === 環境工程學研究所 === 106 === Heavy metals such as Cu, Pb and Zn can enter urban runoff due to intensive automobile emissions, building material weathering, agriculture activities and atmospheric depositions. Bioretention system is one of the most widely used stormwater best management practices (BMPs) for improving water quality of urban runoff. In this study, a bioretention systems consisting of Hydrangea macrophylla, local potting soil, sandy loam and gravel was constructed to investigate the impacts of inflow pH, inflow metal concentrations and inflow volume on the removal of Cu, Pb and Zn. In the end of experiments, the concentrations of metals in the plants were determined to evaluate the bioaccumulation potential. Also, the concentrations of metal in the soil were examined using ITRAX to investigate the metal distribution in the soil column. The results showed that the inflow pH and inflow metal concentration had minor influences on the outflow metal concentrations, while the outflow Pb concentration increased with the increasing inflow volume. Plants could facilitate the removal via phytoremediation and the roots accumulated more metals than the stems and flowers/leaves. Overall, the accumulation of Pb and Zn in the surface layer of soil was higher than those at deeper depths. The removal efficiencies for Pb and Zn were excellent, reaching more than 96% based on total mass. For Cu, it was found that Cu distributed relatively uniformly along the depth and the removal was more than 23%.