Three Carbon-based materials for Submicron Microplastic Removal

Three Carbon-based materials for Submicron Microplastic Removal Abstract Microplastics (MPs) are increasingly reported in surface waters and wastewater-derived streams, raising concern because these particles persist in the environment, can act as carriers for co-contaminants, and may contribute to downstream exposure when effluents impact receiving waters or when reclaimed/recycled water is produced (Carnevale Miino et al., 2024; Iyare et al., 2020; Koelmans et al., 2016; Pérez-Reverón et al., 2022; Tumwesigye et al., 2023). While conventional treatment processes can reduce larger plastic debris, smaller MPs and especially nano-sized plastics are more difficult to capture due to stable suspension and transport behaviors that limit retention by gravity-driven separation and some polishing steps (Chen et al., 2023; Tang & Hadibarata, 2021). Carbon-based media are promising for advanced MP mitigation because they are chemically stable in water and can be produced from renewable feedstocks (e.g., biochar/hydrochar), while their high surface area and pore/particle networks support MP removal via combined surface interactions and physical interception/filtration processes (Amirah Mohd Napi et al., 2023; Anuwa-Amarh et al., 2024; Essien et al., 2025; Zheng et al., 2024). The objective of this study is to optimize MP removal using carbon-based materials and to generate quantitative, engineering-relevant performance metrics that support media selection and process design. Five adsorbents were evaluated under identical laboratory conditions: (1) raw biochar, (2) iron-modified biochar (Fe-biochar), (3) thermally activated biochar produced at 850 °C (850-biochar), (4) activated carbon felt (ACF), and (5) activated carbon (AC). As a model sub-micron MP system, a 0.2 μm fluorescently labeled polystyrene MP suspension was used. Approximately 1 g of each adsorbent was contacted with the MP suspension under controlled mixing. Samples were collected periodically and MP concentration was quantified using a fluorescence spectrophotometer. Adsorption progress was evaluated using time-dependent uptake profiles, and performance was summarized using (i) time required to reach near-equilibrium and (ii) apparent maximum adsorption capacity (QMAX) based on the observed uptake behavior. Tests were replicated to quantify variability and ensure data comparability across media. Among the tested materials, ACF exhibited the strongest overall performance for sub-micron MP capture. ACF reached 95% of its adsorption capacity within 3.17 hours and achieved an apparent maximum adsorption capacity of QMAX = 17.74 ± 3.35 mg MPs g−1 ACF under the tested conditions. The superior behavior of ACF is consistent with its fibrous, highly porous architecture, which increases accessible retention sites and can enhance particle interception/entanglement in addition to surface-based interactions. The remaining carbon-based media (raw and modified biochars and granular activated carbon) exhibited uptake from 1.70 to 3.10 MPs g−1 under the same test conditions, indicating that material architecture and accessible surface features strongly influence both adsorption kinetics and capacity for sub-micron MPs. These results provide a practical, side-by-side benchmark for selecting carbon-based materials to mitigate sub-micron MPs in advanced treatment trains. The rapid kinetics and high capacity observed for ACF suggest potential for reduced required contact time and smaller unit footprint compared with conventional granular media, which is directly relevant to tertiary retrofits at utilities. The comparative dataset also supports a defensible pathway for implementation: rapid laboratory screening to identify high-performing media, followed by column-scale validation (breakthrough behavior) and matrix-sensitive testing in real wastewaters where dissolved organic matter and ionic strength may influence MP retention. Overall, this work advances the evidence base needed to translate emerging MP concerns into actionable treatment strategies using scalable carbon-based material. This paper was presented at WEFTEC 2026 in New Orleans, Louisiana. Presentation time 14:00:00 14:30:00 Session time 13:30:00 15:00:00 Session New, Innovative Wastewater Treatments Session location Ernest N. Morial Convention Center Topic Advanced Level, Facility Operations and Maintenance, Industrial Issues and Treatment Technologies, Research and Innovation Topic Advanced Level, Facility Operations and Maintenance, Industrial Issues and Treatment Technologies, Research and Innovation Author(s) Song, Jianqiao, Venkiteshwaran, Kaushik, Wu, Shenghua Author(s) J. Song 1 , K. Venkiteshwaran 1 , S. Wu 3 Author affiliation(s) University of South Alabama, 1 University of South Alabama, 1 Source Proceedings of the Water Environment Federation Document type Conference Paper Publisher Water Environment Federation Print publication date Sep 2026 DOI 10.2175/193864718825160344 Volume / Issue Content source WEFTEC Copyright 2026 Word count 8 Purchase price $11.50 Get access Log in Purchase content Purchase subscription You may already have access to this content if you have previously purchased this content or have a subscription. Log in Need to create an account? 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