TY - JOUR
T1 - How effective is the retention of microplastics in horizontal flow sand filters treating stormwater?
AU - Rullander, Gabriella
AU - Lorenz, Claudia
AU - Herbert, Roger B.
AU - Strömvall, Ann Margret
AU - Vollertsen, Jes
AU - Dalahmeh, Sahar S.
N1 - Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.
PY - 2023/10/15
Y1 - 2023/10/15
N2 - 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.
AB - 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.
KW - Agglomeration
KW - Lab-scale experiment
KW - Microplastics
KW - Porous media filtration
KW - Stormwater pollution
KW - μ-FTIR analysis
UR - http://www.scopus.com/inward/record.url?scp=85169570192&partnerID=8YFLogxK
U2 - 10.1016/j.jenvman.2023.118690
DO - 10.1016/j.jenvman.2023.118690
M3 - Journal article
C2 - 37586166
AN - SCOPUS:85169570192
SN - 0301-4797
VL - 344
JO - Journal of Environmental Management
JF - Journal of Environmental Management
M1 - 118690
ER -