Vibratory Sorting for Pumice Removal in Microplastic Analysis of Coastal Sediment
Density separation using a wet method is the standard technique for extracting microplastics (MPs) from coastal sediments. However, the 2021 Japanese submarine volcanic eruption introduced substantial pumice into these sediments, complicating the process. Pumice contamination in the floating matter...
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MDPI AG
2025-06-01
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| author | Yusuke Yonaha Kei Nakagawa Ken-ichi Shimizu Mitsuharu Yagi Achara Ussawarujikulchai Hiroshi Asakura |
| author_facet | Yusuke Yonaha Kei Nakagawa Ken-ichi Shimizu Mitsuharu Yagi Achara Ussawarujikulchai Hiroshi Asakura |
| author_sort | Yusuke Yonaha |
| collection | DOAJ |
| description | Density separation using a wet method is the standard technique for extracting microplastics (MPs) from coastal sediments. However, the 2021 Japanese submarine volcanic eruption introduced substantial pumice into these sediments, complicating the process. Pumice contamination in the floating matter from density separation significantly increases the workload of visual sorting. Pumice, distinguished by its spherical shape and hardness, exhibits distinct rolling and bouncing behaviors compared to plastic. In this study, we evaluated the sorting efficiency of a vibratory sorter in separating pumice from floating matter, comparing its performance with the existing methods. We analyzed the progressive behavior and the virtual sorting efficiency of single large- and medium-diameter particles using a vibrating plate and the actual sorting efficiency of mixed large-diameter particles. The maximum Newton’s efficiencies (<i>η</i><sub>max</sub>) for the virtual sorting of single large-diameter pumice and plastic ranged from 0.74 to 1.00, and for medium-diameter particles, from 0.74 to 0.97. Sorting efficiency decreased with finer particles. The <i>η</i><sub>max</sub> for the actual sorting of mixed large-diameter pumice and plastic was between 0.68 and 1.00, lower than the virtual sorting efficiency. While vibratory sorting, based on Newton’s efficiency, does not replace visual sorting, the time required for vibratory sorting is 21% of that required for visual sorting, making it valuable for estimating approximate MP quantities in coastal sediments. Additionally, this study provides a practical method for beach cleanups. |
| format | Article |
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| language | English |
| publishDate | 2025-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Microplastics |
| spelling | doaj-art-23000fdfa9034a0daa85377a22c017ea2025-08-20T02:20:59ZengMDPI AGMicroplastics2673-89292025-06-01423010.3390/microplastics4020030Vibratory Sorting for Pumice Removal in Microplastic Analysis of Coastal SedimentYusuke Yonaha0Kei Nakagawa1Ken-ichi Shimizu2Mitsuharu Yagi3Achara Ussawarujikulchai4Hiroshi Asakura5Graduate School of Integrated Science and Technology, Nagasaki University, 1–14 Bunkyo-machi, Nagasaki 852-8521, JapanInstitute of Integrated Science and Technology, Nagasaki University, 1–14 Bunkyo-machi, Nagasaki 852-8521, JapanInstitute of Integrated Science and Technology, Nagasaki University, 1–14 Bunkyo-machi, Nagasaki 852-8521, JapanInstitute of Integrated Science and Technology, Nagasaki University, 1–14 Bunkyo-machi, Nagasaki 852-8521, JapanFaculty of Environment and Resource Studies, Mahidol University, 999 Puttamonthon 4 Rd. Salaya city, Nakhon Pathom 73170, ThailandInstitute of Integrated Science and Technology, Nagasaki University, 1–14 Bunkyo-machi, Nagasaki 852-8521, JapanDensity separation using a wet method is the standard technique for extracting microplastics (MPs) from coastal sediments. However, the 2021 Japanese submarine volcanic eruption introduced substantial pumice into these sediments, complicating the process. Pumice contamination in the floating matter from density separation significantly increases the workload of visual sorting. Pumice, distinguished by its spherical shape and hardness, exhibits distinct rolling and bouncing behaviors compared to plastic. In this study, we evaluated the sorting efficiency of a vibratory sorter in separating pumice from floating matter, comparing its performance with the existing methods. We analyzed the progressive behavior and the virtual sorting efficiency of single large- and medium-diameter particles using a vibrating plate and the actual sorting efficiency of mixed large-diameter particles. The maximum Newton’s efficiencies (<i>η</i><sub>max</sub>) for the virtual sorting of single large-diameter pumice and plastic ranged from 0.74 to 1.00, and for medium-diameter particles, from 0.74 to 0.97. Sorting efficiency decreased with finer particles. The <i>η</i><sub>max</sub> for the actual sorting of mixed large-diameter pumice and plastic was between 0.68 and 1.00, lower than the virtual sorting efficiency. While vibratory sorting, based on Newton’s efficiency, does not replace visual sorting, the time required for vibratory sorting is 21% of that required for visual sorting, making it valuable for estimating approximate MP quantities in coastal sediments. Additionally, this study provides a practical method for beach cleanups.https://www.mdpi.com/2673-8929/4/2/30microplasticpumicevibratory sortingNewton’s efficiency |
| spellingShingle | Yusuke Yonaha Kei Nakagawa Ken-ichi Shimizu Mitsuharu Yagi Achara Ussawarujikulchai Hiroshi Asakura Vibratory Sorting for Pumice Removal in Microplastic Analysis of Coastal Sediment Microplastics microplastic pumice vibratory sorting Newton’s efficiency |
| title | Vibratory Sorting for Pumice Removal in Microplastic Analysis of Coastal Sediment |
| title_full | Vibratory Sorting for Pumice Removal in Microplastic Analysis of Coastal Sediment |
| title_fullStr | Vibratory Sorting for Pumice Removal in Microplastic Analysis of Coastal Sediment |
| title_full_unstemmed | Vibratory Sorting for Pumice Removal in Microplastic Analysis of Coastal Sediment |
| title_short | Vibratory Sorting for Pumice Removal in Microplastic Analysis of Coastal Sediment |
| title_sort | vibratory sorting for pumice removal in microplastic analysis of coastal sediment |
| topic | microplastic pumice vibratory sorting Newton’s efficiency |
| url | https://www.mdpi.com/2673-8929/4/2/30 |
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