Density-Based Multi-Stage Flotation Sorting of Microplastics in Beach Sand

Md Ariful Islam; Shamim AL Mamun; Hiroshi Asakura

doi:doi:10.11648/j.ajep.20251402.12

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Density-Based Multi-Stage Flotation Sorting of Microplastics in Beach Sand

Md Ariful Islam, Shamim AL Mamun

, Hiroshi Asakura^*

Published in American Journal of Environmental Protection (Volume 14, Issue 2)

Received: 6 March 2025 Accepted: 27 March 2025 Published: 17 April 2025

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Abstract

Microplastics (MPs) are ubiquitous in the environment and pose an increasing concern for the world’s terrestrial and marine ecosystems due to their persistence and potential toxicity. Density sorting of MPs in beach sand, combined with heat treatment to remove impurities such as wood fragments, enhances the analysis of MP contamination. While density sorting does not identify the composition of MPs, it provides insight into their sources and potential for re-drift into the ocean. In this study, we evaluated the accuracy of a multi-stage Flotation sorting technique in separating MPs based on their density in beach sand. A major challenge in density sorting is interference from impurities such as wood fragments. To address this, heat treatment is performed to remove wood fragments. We also evaluated the effects of heat treatment on the density and weight of MPs. The findings indicate that most MPs experienced a density change and a weight loss of less than 4% and 1%, respectively, suggesting the minimal effects of the heat treatment. However, certain types of MPs, such as those containing voids (e.g., PVC-NS), showed significant density changes, which impacted their sorting behavior, resulting in some misclassification during the flotation sorting. Unless the heat treatment caused a density change, the multi-stage Flotation sorting method, including water and saturated calcium chloride (SCC) solutions, achieved high recovery rates (90%-110%) for light MPs, heavy MPs, and wood and sand mixtures. In other words, light and heavy MPs and the wood and sand mixture were separated without misjudgment and loss. Overall, this study confirms the feasibility and efficiency of multi-stage flotation sorting for MP analysis in beach sand and highlights the need to carefully consider heat treatment effects in future environmental studies on MPs.

Published in	American Journal of Environmental Protection (Volume 14, Issue 2)
DOI	10.11648/j.ajep.20251402.12
Page(s)	36-49
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2025. Published by Science Publishing Group

Keywords

Microplastic, Boiling, Density Sorting, Flotation Sorting, Heat Treatment, Wood Fragments, Recovery Rates

References

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APA Style

Islam, M. A., Mamun, S. A., Asakura, H. (2025). Density-Based Multi-Stage Flotation Sorting of Microplastics in Beach Sand. American Journal of Environmental Protection, 14(2), 36-49. https://doi.org/10.11648/j.ajep.20251402.12

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ACS Style

Islam, M. A.; Mamun, S. A.; Asakura, H. Density-Based Multi-Stage Flotation Sorting of Microplastics in Beach Sand. Am. J. Environ. Prot. 2025, 14(2), 36-49. doi: 10.11648/j.ajep.20251402.12

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AMA Style

Islam MA, Mamun SA, Asakura H. Density-Based Multi-Stage Flotation Sorting of Microplastics in Beach Sand. Am J Environ Prot. 2025;14(2):36-49. doi: 10.11648/j.ajep.20251402.12

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@article{10.11648/j.ajep.20251402.12,
  author = {Md Ariful Islam and Shamim AL Mamun and Hiroshi Asakura},
  title = {Density-Based Multi-Stage Flotation Sorting of Microplastics in Beach Sand
},
  journal = {American Journal of Environmental Protection},
  volume = {14},
  number = {2},
  pages = {36-49},
  doi = {10.11648/j.ajep.20251402.12},
  url = {https://doi.org/10.11648/j.ajep.20251402.12},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ajep.20251402.12},
  abstract = {Microplastics (MPs) are ubiquitous in the environment and pose an increasing concern for the world’s terrestrial and marine ecosystems due to their persistence and potential toxicity. Density sorting of MPs in beach sand, combined with heat treatment to remove impurities such as wood fragments, enhances the analysis of MP contamination. While density sorting does not identify the composition of MPs, it provides insight into their sources and potential for re-drift into the ocean. In this study, we evaluated the accuracy of a multi-stage Flotation sorting technique in separating MPs based on their density in beach sand. A major challenge in density sorting is interference from impurities such as wood fragments. To address this, heat treatment is performed to remove wood fragments. We also evaluated the effects of heat treatment on the density and weight of MPs. The findings indicate that most MPs experienced a density change and a weight loss of less than 4% and 1%, respectively, suggesting the minimal effects of the heat treatment. However, certain types of MPs, such as those containing voids (e.g., PVC-NS), showed significant density changes, which impacted their sorting behavior, resulting in some misclassification during the flotation sorting. Unless the heat treatment caused a density change, the multi-stage Flotation sorting method, including water and saturated calcium chloride (SCC) solutions, achieved high recovery rates (90%-110%) for light MPs, heavy MPs, and wood and sand mixtures. In other words, light and heavy MPs and the wood and sand mixture were separated without misjudgment and loss. Overall, this study confirms the feasibility and efficiency of multi-stage flotation sorting for MP analysis in beach sand and highlights the need to carefully consider heat treatment effects in future environmental studies on MPs.
},
 year = {2025}
}

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TY  - JOUR
T1  - Density-Based Multi-Stage Flotation Sorting of Microplastics in Beach Sand

AU  - Md Ariful Islam
AU  - Shamim AL Mamun
AU  - Hiroshi Asakura
Y1  - 2025/04/17
PY  - 2025
N1  - https://doi.org/10.11648/j.ajep.20251402.12
DO  - 10.11648/j.ajep.20251402.12
T2  - American Journal of Environmental Protection
JF  - American Journal of Environmental Protection
JO  - American Journal of Environmental Protection
SP  - 36
EP  - 49
PB  - Science Publishing Group
SN  - 2328-5699
UR  - https://doi.org/10.11648/j.ajep.20251402.12
AB  - Microplastics (MPs) are ubiquitous in the environment and pose an increasing concern for the world’s terrestrial and marine ecosystems due to their persistence and potential toxicity. Density sorting of MPs in beach sand, combined with heat treatment to remove impurities such as wood fragments, enhances the analysis of MP contamination. While density sorting does not identify the composition of MPs, it provides insight into their sources and potential for re-drift into the ocean. In this study, we evaluated the accuracy of a multi-stage Flotation sorting technique in separating MPs based on their density in beach sand. A major challenge in density sorting is interference from impurities such as wood fragments. To address this, heat treatment is performed to remove wood fragments. We also evaluated the effects of heat treatment on the density and weight of MPs. The findings indicate that most MPs experienced a density change and a weight loss of less than 4% and 1%, respectively, suggesting the minimal effects of the heat treatment. However, certain types of MPs, such as those containing voids (e.g., PVC-NS), showed significant density changes, which impacted their sorting behavior, resulting in some misclassification during the flotation sorting. Unless the heat treatment caused a density change, the multi-stage Flotation sorting method, including water and saturated calcium chloride (SCC) solutions, achieved high recovery rates (90%-110%) for light MPs, heavy MPs, and wood and sand mixtures. In other words, light and heavy MPs and the wood and sand mixture were separated without misjudgment and loss. Overall, this study confirms the feasibility and efficiency of multi-stage flotation sorting for MP analysis in beach sand and highlights the need to carefully consider heat treatment effects in future environmental studies on MPs.

VL  - 14
IS  - 2
ER  -

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Author Information

Md Ariful Islam

Graduate School of Fisheries and Environmental Science, Nagasaki University, Bunkyo Machi, Nagasaki, Japan

Contact Email
Shamim AL Mamun

School of Physical and Chemical Sciences, University of Canterbury, Kirkwood Ave., Ilam, Christchurch, New Zealand

Contact Email

http://orcid.org/0000-0003-0437-2701
Hiroshi Asakura

Institute of Integrated Science and Technology, Nagasaki University, Bunkyo Machi, Nagasaki, Japan

Contact Email

http://orcid.org/0000-0002-5999-4260

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APA Style

Islam, M. A., Mamun, S. A., Asakura, H. (2025). Density-Based Multi-Stage Flotation Sorting of Microplastics in Beach Sand. American Journal of Environmental Protection, 14(2), 36-49. https://doi.org/10.11648/j.ajep.20251402.12

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ACS Style

Islam, M. A.; Mamun, S. A.; Asakura, H. Density-Based Multi-Stage Flotation Sorting of Microplastics in Beach Sand. Am. J. Environ. Prot. 2025, 14(2), 36-49. doi: 10.11648/j.ajep.20251402.12

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AMA Style

Islam MA, Mamun SA, Asakura H. Density-Based Multi-Stage Flotation Sorting of Microplastics in Beach Sand. Am J Environ Prot. 2025;14(2):36-49. doi: 10.11648/j.ajep.20251402.12

Copy | Download

@article{10.11648/j.ajep.20251402.12,
  author = {Md Ariful Islam and Shamim AL Mamun and Hiroshi Asakura},
  title = {Density-Based Multi-Stage Flotation Sorting of Microplastics in Beach Sand
},
  journal = {American Journal of Environmental Protection},
  volume = {14},
  number = {2},
  pages = {36-49},
  doi = {10.11648/j.ajep.20251402.12},
  url = {https://doi.org/10.11648/j.ajep.20251402.12},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ajep.20251402.12},
  abstract = {Microplastics (MPs) are ubiquitous in the environment and pose an increasing concern for the world’s terrestrial and marine ecosystems due to their persistence and potential toxicity. Density sorting of MPs in beach sand, combined with heat treatment to remove impurities such as wood fragments, enhances the analysis of MP contamination. While density sorting does not identify the composition of MPs, it provides insight into their sources and potential for re-drift into the ocean. In this study, we evaluated the accuracy of a multi-stage Flotation sorting technique in separating MPs based on their density in beach sand. A major challenge in density sorting is interference from impurities such as wood fragments. To address this, heat treatment is performed to remove wood fragments. We also evaluated the effects of heat treatment on the density and weight of MPs. The findings indicate that most MPs experienced a density change and a weight loss of less than 4% and 1%, respectively, suggesting the minimal effects of the heat treatment. However, certain types of MPs, such as those containing voids (e.g., PVC-NS), showed significant density changes, which impacted their sorting behavior, resulting in some misclassification during the flotation sorting. Unless the heat treatment caused a density change, the multi-stage Flotation sorting method, including water and saturated calcium chloride (SCC) solutions, achieved high recovery rates (90%-110%) for light MPs, heavy MPs, and wood and sand mixtures. In other words, light and heavy MPs and the wood and sand mixture were separated without misjudgment and loss. Overall, this study confirms the feasibility and efficiency of multi-stage flotation sorting for MP analysis in beach sand and highlights the need to carefully consider heat treatment effects in future environmental studies on MPs.
},
 year = {2025}
}

Copy | Download

TY  - JOUR
T1  - Density-Based Multi-Stage Flotation Sorting of Microplastics in Beach Sand

AU  - Md Ariful Islam
AU  - Shamim AL Mamun
AU  - Hiroshi Asakura
Y1  - 2025/04/17
PY  - 2025
N1  - https://doi.org/10.11648/j.ajep.20251402.12
DO  - 10.11648/j.ajep.20251402.12
T2  - American Journal of Environmental Protection
JF  - American Journal of Environmental Protection
JO  - American Journal of Environmental Protection
SP  - 36
EP  - 49
PB  - Science Publishing Group
SN  - 2328-5699
UR  - https://doi.org/10.11648/j.ajep.20251402.12
AB  - Microplastics (MPs) are ubiquitous in the environment and pose an increasing concern for the world’s terrestrial and marine ecosystems due to their persistence and potential toxicity. Density sorting of MPs in beach sand, combined with heat treatment to remove impurities such as wood fragments, enhances the analysis of MP contamination. While density sorting does not identify the composition of MPs, it provides insight into their sources and potential for re-drift into the ocean. In this study, we evaluated the accuracy of a multi-stage Flotation sorting technique in separating MPs based on their density in beach sand. A major challenge in density sorting is interference from impurities such as wood fragments. To address this, heat treatment is performed to remove wood fragments. We also evaluated the effects of heat treatment on the density and weight of MPs. The findings indicate that most MPs experienced a density change and a weight loss of less than 4% and 1%, respectively, suggesting the minimal effects of the heat treatment. However, certain types of MPs, such as those containing voids (e.g., PVC-NS), showed significant density changes, which impacted their sorting behavior, resulting in some misclassification during the flotation sorting. Unless the heat treatment caused a density change, the multi-stage Flotation sorting method, including water and saturated calcium chloride (SCC) solutions, achieved high recovery rates (90%-110%) for light MPs, heavy MPs, and wood and sand mixtures. In other words, light and heavy MPs and the wood and sand mixture were separated without misjudgment and loss. Overall, this study confirms the feasibility and efficiency of multi-stage flotation sorting for MP analysis in beach sand and highlights the need to carefully consider heat treatment effects in future environmental studies on MPs.

VL  - 14
IS  - 2
ER  -

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