Rullander Gabriella, Lorenz Claudia, Herbert Roger B, Strömvall Ann-Margret, Vollertsen Jes, Dalahmeh Sahar S
Department of Earth Sciences, Uppsala University, Villavägen 16, SE-752 36, Sweden.
Aalborg University, Department of The Built Environment, Thomas Manns Vej 23, 9220, Aalborg Øst, Denmark.
J Environ Manage. 2023 Oct 15;344:118690. doi: 10.1016/j.jenvman.2023.118690. Epub 2023 Aug 14.
Microplastics accumulate in stormwater and can ultimately enter freshwater recipients, and pose a serious risk to aquatic life. This study investigated the effectiveness of lab-scale horizontal flow sand filters of differing lengths (25, 50 and 100 cm) in retaining four types of thermoplastic microplastics commonly occurring in stormwater runoff (polyamide, polyethylene, polypropylene, and polyethylene terephthalate). Despite the differences in particle shape, size and density, the study revealed that more than 98% of the spiked microplastics were retained in all filters, with a slightly increased removal with increased filter length. At a flow rate of 1 mL/min and after one week of operation, 62-84% of the added microplastics agglomerated in the first 2 cm of the filters. The agglomerated microplastics included 96% of high-density fibers. Larger-sized particles were retained in the sand media, while microplastics smaller than 50 μm were more often detected in the effluent. Microplastics were quantified and identified using imaging based micro Fourier Transform Infrared Spectroscopy. The efficient retention of microplastics in low-flow horizontal sand filters, demonstrated by the results, highlights their potential importance for stormwater management. This retention is facilitated by various factors, including microplastic agglomeration, particle sedimentation of heavy fibers and favorable particle-to-media size ratios.
微塑料在雨水中积累，最终可能进入淡水水体，对水生生物构成严重威胁。本研究调查了不同长度（25厘米、50厘米和100厘米）的实验室规模水平流砂滤器对雨水中常见的四种热塑性微塑料（聚酰胺、聚乙烯、聚丙烯和聚对苯二甲酸乙二酯）的截留效果。尽管这些微塑料在颗粒形状、大小和密度上存在差异，但研究表明，所有滤器中超过98%的添加微塑料被截留，截留率随滤器长度增加略有提高。在流速为1毫升/分钟且运行一周后，62%-84%的添加微塑料在滤器的前2厘米处聚集。聚集的微塑料中96%为高密度纤维。较大尺寸的颗粒被截留在砂质介质中，而小于50微米的微塑料更常出现在流出物中。使用基于成像的微傅里叶变换红外光谱对微塑料进行定量和识别。结果表明，微塑料在低流量水平砂滤器中的高效截留突出了它们在雨水管理中的潜在重要性。这种截留受到多种因素的促进，包括微塑料的聚集、重质纤维的颗粒沉降以及有利的颗粒与介质尺寸比。
