Regeneration of biochars (pristine and modified/engineered) and economic analysis of their use in the removal of per- and polyfluoroalkyl substances (PFAS) from water/wastewater

Highlights

	● Biochar application for PFAS sorptive removal from aqueous samples was reviewed.
	● Regeneration/reuse techniques for the spent biochars were summarized.
	● Economic analysis of biochar use in PFAS removal from water was presented.

Abstract

Currently, there is an increasing interest in developing efficient and cost-effective treatment technologies to remediate per- and polyfluoroalkyl substances (PFAS) in water. Biochars (pristine and modified/engineered) can be a good candidate among porous pyrogenic carbonaceous materials for the sorptive removal of PFAS from water/wastewater. There is a need to focus on developing efficient, environmentally friendly, and cost-effective techniques for desorbing PFAS from spent biochars (pristine and modified/engineered) to enable potential reuse or suitable disposal of these adsorbents, facilitating their future full-scale application in the water sector. This review article briefly compiles the state-of-the-art knowledge on the: (i) application of pristine and modified/engineered biochars for the sorptive removal of PFAS from aqueous samples; (ii) regeneration/reuse techniques for the spent biochars; and (iii) economic analysis of their use in PFAS removal from water/wastewater. Further investigations on (i) better modifying/engineering biochars to remove specially short-chain PFAS species in real environmental water samples due to challenging nature of their removal using conventional treatment technologies; (ii) feasible low-energy, environmentally friendly, and cost-effective strategies for regeneration/reuse of the spent biochars (pristine and modified/engineered) and management of their end-of-life; and (iii) large-scale and continuous column sorption operation for the real water/wastewater samples are still desirable to apply biochars for PFAS removal at full-scale in the future.

Graphical abstract

Keywords

Per- and polyfluoroalkyl substances / Biochar / Sorption / Water / Reuse / Cost

References

[1] Abunada Z, Alazaiza M Y D, Bashir M J K. (2020). An overview of per- and polyfluoroalkyl substances (PFAS) in the environment: source, fate, risk and regulations. Water, 12(12): 3590

[2] ATSDR (2024). PFAS in the U.S. Population. Atlanta: Agency for Toxic Substances and Disease Registry

[3] Ahmad M, Rajapaksha A U, Lim J E, Zhang M, Bolan N, Mohan D, Vithanage M, Lee S S, Ok Y S. (2014). Biochar as a sorbent for contaminant management in soil and water: a review. Chemosphere, 99: 19–33

[4] Alhashimi H A, Aktas C B. (2017). Life cycle environmental and economic performance of biochar compared with activated carbon: a meta-analysis. Resources, Conservation and Recycling, 118: 13–26

[5] Alinezhad A, Sasi P C, Zhang P, Yao B, Kubátová A, Golovko S A, Golovko M Y, Xiao F. (2022). An investigation of thermal air degradation and pyrolysis of per- and polyfluoroalkyl substances and aqueous film-forming foams in soil. ACS ES&T Engineering, 2(2): 198–209

[6] Behnami A, Pourakbar M, Ayyar A S R, Lee J W, Gagnon G, Benis K Z. (2024). Treatment of aqueous per- and poly-fluoroalkyl substances: a review of biochar adsorbent preparation methods. Chemosphere, 357: 142088

[7] Buck R C, Franklin J, Berger U, Conder J M, Cousins I T, De Voogt P, Jensen A A, Kannan K, Mabury S A, van Leeuwen S P J. (2011). Perfluoroalkyl and polyfluoroalkyl substances in the environment: terminology, classification, and origins. Integrated Environmental Assessment and Management, 7(4): 513–541

[8] Cerlanek A, Liu L, Robey N, Timshina A S, Bowden J A, Townsend T G. (2024). Assessing construction and demolition wood-derived biochar for in-situ per- and polyfluoroalkyl substance (PFAS) removal from landfill leachate. Waste Management, 174: 382–389

[9] Collivignarelli M C, Bellazzi S, Caccamo F M, Calatroni S, Milanese C, Baldi M, Abbà A, Sorlini S, Bertanza G. (2023). Removal of per- and polyfluoroalkyl substances by adsorption on innovative adsorbent materials. Sustainability, 15(17): 13056

[10] Cousins I T. (2015). Per- and polyfluoroalkyl substances in materials, humans and the environment. Chemosphere, 129: 1–3

[11] Dalahmeh S S, Alziq N, Ahrens L. (2019). Potential of biochar filters for onsite wastewater treatment: effects of active and inactive biofilms on adsorption of per- and polyfluoroalkyl substances in laboratory column experiments. Environmental Pollution, 247: 155–164

[12] Deng J, Han J, Hou C, Zhang Y, Fang Y, Du W X, Li M, Yuan Y, Tang C, Hu X. (2023). Efficient removal of per- and polyfluoroalkyl substances from biochar composites: cyclic adsorption and spent regenerant degradation. Chemosphere, 341: 140051

[13] Dey D, Shafi T, Chowdhury S, Dubey B K, Sen R. (2024). Progress and perspectives on carbon-based materials for adsorptive removal and photocatalytic degradation of perfluoroalkyl and polyfluoroalkyl substances (PFAS). Chemosphere, 351: 141164

[14] Fang J, Li S, Qiu R, Zhang WX. (2024). “Forever chemicals”: a sticky environmental problem. Frontiers of Environmental Science & Engineering, 18: 131

[15] Gagliano E, Sgroi M, Falciglia P P, Vagliasindi F G A, Roccaro P. (2020). Removal of poly- and perfluoroalkyl substances (PFAS) from water by adsorption: role of PFAS chain length, effect of organic matter and challenges in adsorbent regeneration. Water Research, 171: 115381

[16] Gao P, Cui J, Deng Y. (2021). Direct regeneration of ion exchange resins with sulfate radical-based advanced oxidation for enabling a cyclic adsorption-regeneration treatment approach to aqueous perfluorooctanoic acid (PFOA). Chemical Engineering Journal, 405: 126698

[17] Giesy J P, Kannan K. (2001). Global distribution of perfluorooctane sulfonate in wildlife. Environmental Science & Technology, 35(7): 1339–1342

[18] Grunfeld D A, Gilbert D, Hou J, Jones A M, Lee M J, Kibbey T C G, O’Carroll D M. (2024). Underestimated burden of per-and polyfluoroalkyl substances in global surface waters and groundwaters. Nature Geoscience, 17: 340–346

[19] Hansen K J, Clemen L A, Ellefson M E, Johnson H O. (2001). Compound-specific, quantitative characterization of organic: fluorochemicals in biological matrices. Environmental Science & Technology, 35(4): 766–770

[20] He J, Boersma M, Song Z, Krebsbach S, Fan D, Duin E C, Wang D. (2024). Biochar and surfactant synergistically enhanced PFAS destruction in UV/sulfite system at neutral pH. Chemosphere, 353: 141562

[21] ITRC (2023). PFAS－Per- and Polyfluoroalkyl Substances, PFAS Fact Sheets. Washington, DC: Interstate Technology and Regulatory Council

[22] Jafarinejad S. (2024). Some possible process configurations for modern wastewater treatment plants for per- and polyfluoroalkyl substances (PFASs) removal. Sustainability, 16(18): 8109

[23] Ji B, Kang P, Wei T, Zhao Y. (2020). Challenges of aqueous per- and polyfluoroalkyl substances (PFASs) and their foreseeable removal strategies. Chemosphere, 250: 126316

[24] JirkaS, Tomlinson T (2015). State of the Biochar Industry 2014: a Survey of Commercial Activity in the Biochar Sector. New York: International Biochar Initiative (IBI)

[25] Kancharla S, Alexandridis P, Tsianou M. (2022). Sequestration of per- and polyfluoroalkyl substances (PFAS) by adsorption: surfactant and surface aspects. Current Opinion in Colloid & Interface Science, 58: 101571

[26] Kotthoff M, Müller J, Jürling H, Schlummer M, Fiedler D. (2015). Perfluoroalkyl and polyfluoroalkyl substances in consumer products. Environmental Science and Pollution Research International, 22(19): 14546–14559

[27] Krebsbach S, He J, Adhikari S, Olshansky Y, Feyzbar F, Davis L C, Oh T S, Wang D. (2023a). Mechanistic understanding of perfluorooctane sulfonate (PFOS) sorption by biochars. Chemosphere, 330: 138661

[28] Krebsbach S, He J, Oh T S, Wang D. (2023b). Effects of environmental factors on the sorption of per- and polyfluoroalkyl substances by biochars. ACS ES&T Water, 3(10): 3437–3446

[29] Lenka S P, Kah M, Padhye L P. (2021). A review of the occurrence, transformation, and removal of poly- and perfluoroalkyl substances (PFAS) in wastewater treatment plants. Water Research, 199: 117187

[30] Liu N, Wu C, Lyu G, Li M. (2021). Efficient adsorptive removal of short-chain perfluoroalkyl acids using reed straw-derived biochar (RESCA). Science of the Total Environment, 798: 149191

[31] Liu Y Y, Blowes D W, Ptacek C J, Groza L G. (2019). Removal of pharmaceutical compounds, artificial sweeteners, and perfluoroalkyl substances from water using a passive treatment system containing zero-valent iron and biochar. Science of the Total Environment, 691: 165–177

[32] Liu Y Y, Ptacek C J, Baldwin R J, Cooper J M, Blowes D W. (2020). Application of zero-valent iron coupled with biochar for removal of perfluoroalkyl carboxylic and sulfonic acids from water under ambient environmental conditions. Science of the Total Environment, 719: 137372

[33] Liu Z, Chen Z, Gao J, Yu Y, Men Y, Gu C, Liu J. (2022). Accelerated degradation of perfluorosulfonates and perfluorocarboxylates by UV/sulfite + iodide: reaction mechanisms and system efficiencies. Environmental Science & Technology, 56(6): 3699–3709

[34] Lu D, Sha S, Luo J, Huang Z, Jackie X Z. (2020). Treatment train approaches for the remediation of per- and polyfluoroalkyl substances (PFAS): a critical review. Journal of Hazardous Materials, 386: 121963

[35] LyuX, XiaoF, ShenC, Chen J, ParkCM, SunY, FluryM, WangD (20222022. Per- and polyfluoroalkyl substances (PFAS) in subsurface environments: occurrence, fate, transport, and research prospect. Reviews of Geophysics, 60(3), e2021RG000765 doi:10.1029/2021RG000765

[36] Militao I M, Roddick F, Fan L, Zepeda L C, Parthasarathy R, Bergamasco R. (2023). PFAS removal from water by adsorption with alginate-encapsulated plant albumin and rice straw-derived biochar. Journal of Water Process Engineering, 53: 103616

[37] Militao I M, Roddick F A, Bergamasco R, Fan L. (2021). Removing PFAS from aquatic systems using natural and renewable material-based adsorbents: a review. Journal of Environmental Chemical Engineering, 9(4): 105271

[38] Mohan D, Sarswat A, Ok Y S, Pittman C U Jr. (2014). Organic and inorganic contaminants removal from water with biochar, a renewable, low cost and sustainable adsorbent: a critical review. Bioresource Technology, 160: 191–202

[39] Nguyen M D, Sivaram A K, Megharaj M, Webb L, Adhikari S, Thomas M, Surapaneni A, Moon E M, Milne N A. (2023). Investigation on removal of perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS) using water treatment sludge and biochar. Chemosphere, 338: 139412

[40] PapesB (20222022. Per- and Polyfluoroalkyl Substances Mitigation from Contaminated Groundwater Using Halophyte and Cow Bone Biochars. Thesis for the Master’s Degree. Houghton: Michigan Technological University

[41] Rodrigo P M, Navarathna C, Pham M T H, McClain S J, Stokes S, Zhang X, Perez F, Gunatilake S R, Karunanayake A G, Anderson R. . (2022). Batch and fixed bed sorption of low to moderate concentrations of aqueous per- and poly-fluoroalkyl substances (PFAS) on Douglas fir biochar and its Fe₃O₄ hybrids. Chemosphere, 308: 136155

[42] Salvatore D, Mok K, Garrett K K, Poudrier G, Brown P, Birnbaum L S, Goldenman G, Miller M F, Patton S, Poehlein M. . (2022). Presumptive contamination: a new approach to PFAS contamination based on likely sources. Environmental Science & Technology Letters, 9(11): 983–990

[43] Shakoor M B, Ye Z L, Chen S. (2021). Engineered biochars for recovering phosphate and ammonium from wastewater: a review. Science of the Total Environment, 779: 146240

[44] Siriwardena D P, James R, Dasu K, Thorn J, Iery R D, Pala F, Schumitz D, Eastwood S, Burkitt N. (2021). Regeneration of per- and polyfluoroalkyl substance-laden granular activated carbon using a solvent based technology. Journal of Environmental Management, 289: 112439

[45] Sörengård M, Östblom E, Köhler S, Ahrens L. (2020). Adsorption behavior of per- and polyfluoralkyl substances (PFASs) to 44 inorganic and organic sorbents and use of dyes as proxies for PFAS sorption. Journal of Environmental Chemical Engineering, 8(3): 103744

[46] SteigerwaldJ M (20222022. Development of a Novel Biochar-Molecularly Imprinted Polymer Composite for Targeted Adsorption of Perfluoroalkyl Substances in Water Treatment Applications. Thesis for the Master’s Degree. Seattle: University of Washington

[47] Steigerwald J M, Ray J R. (2021). Adsorption behavior of perfluorooctanesulfonate (PFOS) onto activated spent coffee grounds biochar in synthetic wastewater effluent. Journal of Hazardous Materials Letters, 2: 100025

[48] US EPA (2023a). Our Current Understanding of the Human Health and Environmental Risks of PFAS. Washington, DC: United States Environmental Protection Agency

[49] US EPA (2023b). PFAS Explained. Washington, DC: United States Environmental Protection Agency.

[50] US EPA (2024). Per- and Polyfluoroalkyl Substances (PFAS), Final PFAS National Primary Drinking Water Regulation. Washington, DC: United States Environmental Protection Agency

[51] Vo H N P, Ngo H H, Guo W, Nguyen T M H, Li J, Liang H, Deng L, Chen Z, Nguyen T A H. (2020). Poly- and perfluoroalkyl substances in water and wastewater: a comprehensive review from sources to remediation. Journal of Water Process Engineering, 36: 101393

[52] Vo H N P, Nguyen T M H, Ngo H H, Guo W, Shukla P. (2022). Biochar sorption of perfluoroalkyl substances (PFASs) in aqueous film-forming foams-impacted groundwater: effects of PFASs properties and groundwater chemistry. Chemosphere, 286: 131622

[53] Wang F, Shih K, Lu X, Liu C. (2013). Mineralization behavior of fluorine in perfluorooctanesulfonate (PFOS) during thermal treatment of lime-conditioned sludge. Environmental Science & Technology, 47(6): 2621–2627

[54] Wang J, Wang S. (2019). Preparation, modification and environmental application of biochar: a review. Journal of Cleaner Production, 227: 1002–1022

[55] Wang Z, Alinezhad A, Nason S, Xiao F, Pignatello J J. (2023a). Enhancement of per- and polyfluoroalkyl substances removal from water by pyrogenic carbons: tailoring carbon surface chemistry and pore properties. Water Research, 229: 119467

[56] Wang Z, Alinezhad A, Sun R, Xiao F, Pignatello J J. (2023b). Pre- and postapplication thermal treatment strategies for sorption enhancement and reactivation of biochars for removal of per- and polyfluoroalkyl substances from water. ACS ES&T Engineering, 3(2): 193–200

[57] Wu Y, Qi L, Chen G. (2022). A mechanical investigation of perfluorooctane acid adsorption by engineered biochar. Journal of Cleaner Production, 340: 130742

[58] Yu H, Chen H, Zhang P, Yao Y, Zhao L, Zhu L, Sun H. (2023). In situ self-sacrificial synthesis of polypyrrole/biochar composites for efficiently removing short- and long-chain perfluoroalkyl acid from contaminated water. Journal of Environmental Management, 344: 118745

[59] Zhang D Q, He Q, Wang M, Zhang W, Liang Y. (2021). Sorption of perfluoroalkylated substances (PFASs) onto granular activated carbon and biochar. Environmental Technology, 42(12): 1798–1809

[60] Zhang Y, Tan X, Lu R, Tang Y, Qie H, Huang Z, Zhao J, Cui J, Yang W, Lin A. (2023). Enhanced removal of polyfluoroalkyl substances by simple modified biochar: adsorption performance and theoretical calculation. ACS ES&T Water, 3(3): 817–826

[61] Zhou T, Li X, Liu H, Dong S, Zhang Z, Wang Z, Li J, Nghiem L D, Khan S J, Wang Q. (2024). Occurrence, fate, and remediation for per-and polyfluoroalkyl substances (PFAS) in sewage sludge: a comprehensive review. Journal of Hazardous Materials, 466: 133637

Acknowledgements

All authors acknowledge support from the United States Environmental Protection Agency (No. SU840873). In addition, S. J. acknowledges support from the Procter & Gamble (P&G) (No. DA24-00647) and the 2024–2025 Henry C. McBay Faculty Research Fellowship from UNCF.

Conflict of Interests

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

RIGHTS & PERMISSIONS

2025 Higher Education Press 2025