Søberg Laila C, Winston Ryan, Viklander Maria, Blecken Godecke-Tobias
Urban Water, Luleå University of Technology, 97187, Luleå, Sweden.
Departments of Food, Agricultural, and Biological Engineering and Civil, Environmental, and Geodetic Engineering, Ohio State University, 590 Woody Hayes Drive, Columbus, OH, 43210, United States of America.
Water Res X. 2019 May 4;4:100032. doi: 10.1016/j.wroa.2019.100032. eCollection 2019 Aug 1.
The dissolved metal adsorption and association was determined for ten different filter materials recommended and/or implemented in bioretention facilities. Batch adsorption and batch kinetic experiments were performed at lab-scale using both single and multi-metal solutions. Metal strengths and association were determined by sequential extraction analysis. All materials adsorbed metals and 90% of adsorption occurred within 1 h. However, as metal solutions became more complex, adsorption behavior changed. Generally, filter materials classified as sand with a naturally high pH, relatively low organic matter (OM) content and large specific surface area seem to be good choices for removing dissolved metals. Additionally, a chalk additive might improve metal adsorption whereas biochar did not significantly improve metal retention and may be an unwanted (due to degradation over time) extra source of OM. Regardless of filter material, metals primarily adsorbed to the exchangeable form which indicates that metal adsorption might not be permanent, but rather substantially reversible in some cases. More research is needed to assess whether dissolved metals adsorbed in filter materials of bioretention systems pose a delayed threat instead of an immediate threat. Finally, the authors strongly recommend filter materials intended for stormwater bioretention facilities to be tested prior to implementation.
对生物滞留设施中推荐和/或使用的十种不同过滤材料进行了溶解金属吸附和结合测定。在实验室规模下，使用单金属和多金属溶液进行了批量吸附和批量动力学实验。通过顺序萃取分析确定金属强度和结合情况。所有材料都能吸附金属，且90%的吸附在1小时内发生。然而，随着金属溶液变得更加复杂，吸附行为发生了变化。一般来说，归类为沙子的过滤材料，具有天然的高pH值、相对较低的有机质（OM）含量和较大的比表面积，似乎是去除溶解金属的良好选择。此外，白垩添加剂可能会改善金属吸附，而生物炭并没有显著提高金属保留率，并且可能是一个不必要的（由于随时间降解）额外的OM来源。无论过滤材料如何，金属主要吸附到可交换形式，这表明金属吸附可能不是永久性的，而是在某些情况下基本上是可逆的。需要更多的研究来评估生物滞留系统过滤材料中吸附的溶解金属是否构成延迟威胁而非直接威胁。最后，作者强烈建议用于雨水生物滞留设施的过滤材料在实施前进行测试。
