University of Glasgow, College of Science and Engineering, Glasgow, Scotland, UK.
Water Sci Technol. 2013;68(3):674-80. doi: 10.2166/wst.2013.259.
Sustainable urban Drainage Systems (SuDS) filter drains are simple, low-cost systems utilized as a first defence to treat road runoff by employing biogeochemical processes to reduce pollutants. However, the mechanisms involved in pollution attenuation are poorly understood. This work aims to develop a better understanding of these mechanisms to facilitate improved SuDS design. Since heavy metals are a large fraction of pollution in road runoff, this study aimed to enhance heavy metal removal of filter drain gravel with an iron oxide mineral amendment to increase surface area for heavy metal scavenging. Experiments showed that amendment-coated and uncoated (control) gravel removed similar quantities of heavy metals. Moreover, when normalized to surface area, iron oxide coated gravels (IOCGs) showed poorer metal removal capacities than uncoated gravel. Inspection of the uncoated microgabbro gravel indicated that clay particulates on the surface (a natural product of weathering of this material) augmented heavy metal removal, generating metal sequestration capacities that were competitive compared with IOCGs. Furthermore, when the weathered surface was scrubbed and removed, metal removal capacities were reduced by 20%. When compared with other lithologies, adsorption of heavy metals by microgabbro was 10-70% higher, indicating that both the lithology of the gravel, and the presence of a weathered surface, considerably influence its ability to immobilize heavy metals. These results contradict previous assumptions which suggest that gravel lithology is not a significant factor in SuDS design. Based upon these results, weathered microgabbro is suggested to be an ideal lithology for use in SuDS.
可持续城市排水系统 (SuDS) 过滤排水系统是一种简单、低成本的系统，用作处理道路径流的第一道防线，利用生物地球化学过程减少污染物。然而，对于污染衰减的机制还了解甚少。本工作旨在更好地理解这些机制，以促进更好的 SuDS 设计。由于重金属是道路径流中污染物的主要成分，因此本研究旨在通过添加氧化铁矿物改良剂来增强滤水管砾石对重金属的去除能力，以增加重金属捕集的表面积。实验表明，改良剂涂层和未涂层（对照）砾石去除了相似数量的重金属。此外，当归一化到表面积时，氧化铁涂层砾石（IOCG）的金属去除能力比未涂层砾石差。对未涂层的微辉长岩砾石的检查表明，表面上的粘土颗粒（这种材料风化的天然产物）增强了重金属的去除，产生了与 IOCG 竞争的金属螯合能力。此外，当风化表面被擦洗和去除时，金属去除能力降低了 20%。与其他岩性相比，微辉长岩对重金属的吸附率高 10-70%，表明砾石的岩性以及风化表面的存在极大地影响了其固定重金属的能力。这些结果与先前的假设相矛盾，该假设表明砾石岩性不是 SuDS 设计中的重要因素。基于这些结果，建议风化的微辉长岩是 SuDS 中使用的理想岩性。
