Per- and Polyfluoroalkyl Substances (PFAS)

Introduction

This section provides an overview of remediation technologies that have been used or are being evaluated to treat PFAS-contaminated media. Most of the available information concerns the treatment of drinking water, wastewater, and groundwater; treatment of soils and sediments has received less attention. The remediation technologies addressed below are primarily focused on PFOS and PFOA; however, researchers such as Liu et al. 2015 and Place and Field 2012 report that many other PFASs may be present in wastewater, surface water, and at firefighter training areas or other sites where aqueous film-forming foam (AFFF) was used. Technologies that are able to treat PFOS and PFOA effectively may be ineffective for other PFASs with different chemical and physical properties. In addition, co-contaminants such as hydrocarbons and chlorinated solvents may also be present at sites contaminated with PFAS. Oxidative technologies such as in situ chemical oxidation, which are often applied to these contaminants, may transform polyfluorinated precursors into PFOS and PFOA (Merina et al 2016). Air stripping, which is often applied to remove chlorinated solvents from extracted groundwater, may result in PFAS being released as aerosols (Oliaei et a. 2013). These potential impacts may affect the selection and implementation of remedies at PFAS sites.

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Technology Overviews

The following are summary descriptions of remediation technologies and are hyperlinked to subsections containing citations to relevant papers and reports for additional reading. Each citation in the subsection is followed by a brief description that indicates the focus or scope of the publication's content. The available information for some technologies is limited because remediating PFAS contamination has only recently been contemplated. EPA does not endorse any technology or the findings, conclusions, or recommendations of the publications. Readers are encouraged to consult the linked text for a description of results, conclusions, and recommendations.

Remediation Technologies Used for PFAS-Contaminated Media

Excavation and Off-Site Disposal. Excavation of soil and sediment with disposal at an off-site landfill has been selected as a means to remove and contain PFAS-contaminated media (MPCA 2008a, 2008b, and 2009).

Pump and Treat. Extraction of groundwater followed by treatment with granular activated carbon has been selected as a means to control the migration of PFAS-contaminated groundwater (MPCA 2008a, 2008b, and 2009).

Remediation Technologies Being Evaluated for PFAS-Contaminated Media

Adsorption. Activated carbon in either the powdered or granular form can be effective at removing PFOA and PFOS from water (USEPA 2016a and b). Bench- and pilot-scale studies are required to select the most effective product and contact time (Cummings et al. 2015) and to evaluate treatment costs (USEPA 2016a and b). Proprietary adsorbents such as RemBind™ and PefluorAd are being marketed as alternatives or complements to activated carbon (Birk 2016). Disposal and treatment of exhausted activated carbon or used adsorbents may also be an important consideration. Ion exchange resin has two broad resin categories: cationic and anionic. Cationic exchange resins may be effective for treating water containing positively charged PFAS (e.g., perfluoroalkyl sulfonamide amines). Anion exchange resins have been shown to be effective for treating negatively charged PFAS (e.g., PFOA and PFOS) and require periodic regeneration to restore uptake capacity (Dudley et al. 2015, USEPA 2016a and b).

Bioremediation. The microbial transformation of polyfluorinated precursors to yield perfluorinated compounds is likely to occur in aerobic environments (Dasu and Lee 2016, Liu and Avendaño 2013). A limited number of studies have found that perfluorinated compounds such as PFOS and PFOA are resistant to microbial degradation transformation in aerobic environments; few detailed studies under anaerobic conditions have been completed to date (Liu and Avendaño 2013).

Chemical Oxidation. Common drinking water oxidative/disinfection agents such as packed tower aeration, chloramination, chlorination, ozonation, potassium permanganate, ultraviolet (UV) treatment, and advanced oxidation processes (AOPs) have been shown to be ineffective for PFOS and PFOA (Dickenson and Higgins 2016, EPA 2016a and b). However, bench-scale work has shown the potential for some oxidants and oxidant systems to degrade some PFASs (Crimi 2016). There is a concern that polyfluorinated precursors may be transformed into oxidation-resistant perfluoroalkyl carboxylates during in situ chemical oxidation (Place and Field 2012).

Chemical Reduction. Preliminary research has shown that a number of chemical reduction techniques are capable of degrading some PFASs (Crimi 2016).

Electrochemical Oxidation. Bench-scale testing has shown that electrochemical oxidation of PFASs at concentrations of less than 200 mg/L is achievable for some anode and electrolyte combinations (Niu et al. 2016).

Incineration and Thermal Treatment. Research to date has focused on PFAS-containing solid waste showing that fluorotelomer-based acrylic polymer was destroyed in a laboratory-scale reactor designed to simulate municipal incineration conditions (Yamada et al. 2005). Other research has focused on the ex situ thermal treatment of PFOS-containing sludge (Wang et al. 2013).

Membrane Filtration. High pressure membranes, such as those used in reverse osmosis and nanofiltration systems, can reject particulates and dissolved species such as PFAS (EPA 2016a and b). Reverse Osmosis (RO) involves retaining PFASs on the pressurized side of a membrane and has been shown in both bench- and full-scale applications to remove PFOS and PFOA from water (Cummings et al. 2015, EPA 2016a and b). Nanofiltration is similar to RO, although it operates at lower pressures, and has been shown in bench-scale experiments to remove PFOS from water (Cummings et al. 2015). Disposal and treatment of the retained fluid (i.e., rejectate), which potentially contains high concentrations of PFASs, may also be an important consideration.

Solidification/Stabilization. There are reports of mixing adsorbents with soil to reduce the mobility of PFASs (Birk 2016).

Sonochemical Treatment. Bench-scale research has been completed demonstrating the applicability of treating PFASs in water by sonolysis (Merino et al. 2016).

Additional information on a wide variety of treatment technologies for drinking water, some of which may be applicable to PFOS or PFOA, can be found in EPA's Drinking Water Treatability Database.

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Overviews of Multiple Technologies

Abiotic Treatment Technologies for In-Site Remediation of Persistent Perfluoroalkyl Acids
Lee, L.S., S. Park, and J. Zenobio.
NICOLE Workshop, June 26, 2015, Manchester, UK, 37 slides, 2015

This presentation surveys abiotic treatment technologies and indicates (with references) where there has been some success and which technologies, to date, have not shown promise.

Behaviour and Fate of Perfluoroalkyl and Polyfluoroalkyl Substances (PFASs) in Drinking Water Treatment: A Review
Rahman, M.F., S. Peldszus, and W.B. Anderson.
Water Research 50:318-340(2014) [Abstract]

This peer reviewed paper reviews PFAS characteristics, their occurrence in surface water, and their fate in drinking water treatment processes.

Degradation and Removal Methods for Perfluoroalkyl and Polyfluoroalkyl Substances in Water
Merino, N., Y. Qu, R. Deeb, E. Hawley, M. Hoffmann, and S. Mahendra.
Environmental Engineering Science 33(9):615-649(2016) [Abstract]

This review presents a comprehensive summary of several categories of treatment approaches: (1) sorption using activated carbon, ion exchange, or other sorbents, (2) advanced oxidation processes, (3) advanced reduction processes using aqueous iodide or dithionite and sulfite, (4) thermal and nonthermal destruction, (5) microbial treatment, and (6) other treatment processes, including ozonation under alkaline conditions, permanganate oxidation, vitamin-B12 and Ti(III) citrate reductive defluorination, and ball milling.

Developing Innovative Treatment Technologies for PFAS-Containing Wastes
Berg, C., B. Crone, B. Gullett, M. Higuchi, M.J. Krause, P.M. Lemieux, T. Martin, E.P. Shields, E. Struble, E. Thoma, and A. Whitehill.
Journal of the Air & Waste Management Association 72(6):540-555(2022)

EPA's Office of Research and Development (ORD) commissioned the PFAS Innovative Treatment Team (PITT) to provide new perspectives on treatment and disposal of high-priority PFAS-containing wastes and complement its ongoing research efforts addressing PFAS contamination. During its six-month tenure, the team was charged with identifying and developing promising solutions to destroy PFAS. The PITT examined emerging technologies for PFAS waste treatment and selected four technologies for further investigation: mechanochemical treatment, electrochemical oxidation, gasification and pyrolysis, and supercritical water oxidation. This paper examines the four novel, non-combustion technologies or applications to treat PFAS wastes. The technologies are introduced along with their current state of development and areas for further development. This information will be useful for developers, policymakers, and facility managers facing increasing issues with disposal of PFAS wastes.

Development of Scalable Reactive Transport Framework for PFAS
Johnson, C.D., C.E Bagwell, and R.L. Bence.
Pacific Northwest National Laboratory Report PNNL-35136, 46, 2023.

This work provides kinetic reaction modules that represent an initial offering at functionality representing PFAS migration and reaction in groundwater aquifer flow and transport models. One reaction kinetics module provides a method to model kinetically limited adsorption using a mass transfer model. The second module represents biological transformation of 8:2 FTOH and daughter species, illustrating how a complex reaction pathway network can be represented. Both reaction modules allow spatially variable parameter values to simulate various remediation approaches (e.g., a permeable reactive barrier, volumetric treatment, or variations in geochemical conditions). The PFAS reaction modules are intended to provide tools for practitioners to aid in the selection, design, and assessment of potential in situ PFAS remediation strategies. Application of these modules will require that practitioners determine whether these reaction modules are relevant to a particular site and remediation approach and whether the assumptions and uncertainty are acceptable. As PFAS remediation technologies and scientific understanding advance, it is anticipated that these modules will be refined or replaced to match new knowledge.

Drinking Water Health Advisory for Perfluorooctane Sulfonate (PFOS)
U.S. EPA, Office of Water.
EPA 822-R-16-004, 88 pp, 2016

Chapter 10 contains a review of the effectiveness of current drinking water treatment processes in effectively treating PFOS and references to papers describing the performance of these technologies.

Drinking Water Health Advisory for Perfluorooctanoic Acid (PFOA)
U.S. EPA, Office of Water.
EPA 822-R-16-005, 103 pp, 2016

The document offers an overview in chapter 10 of the effectiveness of current drinking water treatment processes in effectively treating PFOS and references to papers describing the performance of these technologies.

The Emerging Issue: PFAS–Poly- and Perfluoroalkyl Substances–Big Picture, Challenges and Solutions
Ross, I.
RemTech 2016: Remediation Technologies Symposium, 50 slides, 2016

An overview of PFAS issues is followed by a review of potential PFAS remediation options (slides 32-49).

Environmental Fate and Effects of Poly and Perfluoroalkyl Substances (PFAS)
Pancras, T., G. Schrauwen, T. Held, K. Baker, I. Ross, and H. Slenders.
Concawe, Report No. 8/16, 121 pp, 2016

With an emphasis on chemicals found in AFFF products, Chapter 8 in this report provides brief discussions on the viability of various treatment options for soil and groundwater.

Field Demonstration of Coupling Ion-Exchange Resin with Electrochemical Oxidation for Enhanced Treatment of Per- And Polyfluoroalkyl Substances (PFAS) in Groundwater
Liang, S., R. Mora, Q. Huang, R. Casson, Y. Wang, S. Woodard, and H. Anderson. Chemical Engineering Journal Advances 9:100216(2022)

A pilot-scale field demonstration evaluated remediation of aqueous film-forming foam (AFFF)-contaminated groundwater using a coupled regenerable ion exchange resin (IXR) and electrochemical oxidation (EO) treatment train. The pilot-scale IXR system incorporated a novel resin regeneration process that recovers and reuses the regenerant solutions. The IXR system removed PFAS from ~1,000,000 L (~260,000 gallons) of AFFF-contaminated groundwater; treated effluent was ND for PFOA and PFOS. The concentrated waste stream treated on-site by an EO system achieved 80-98% destruction of PFOA and PFOS. Results show the promise of coupling regenerable IXR with EO for cost-effective removal to concentrate and destroy PFAS in groundwater.

Overview of Remediation Technologies Potentially Applicable to Perfluoroalkyl Substances
Hohenstein, G.
2016 Emerging Contaminants Summit, 34 slides, 2016

This presentation evaluates 3M Company's experience with a variety of technologies for treating PFASs.

Pandora's PFAS Box: Life Cycle Exposure Considerations of Treatment Options for PFAS in Groundwater
L.C. Hall, J.T. Wilson, and J.G.A. Birnstingl
Remediation 34(2):e21775(2024)

This commentary considers four PFAS remediation technologies (granular activated carbon, ion-exchange resin, foam fractionation, and in situ remediation with colloidal activated carbon) and identifies places in the life cycle that have the potential for environmental releases from the handling, transport, disposal, regeneration, and/or destruction of remediation wastes. It also identifies where those releases have the potential to result in human exposure to PFAS, focusing on the long-chain PFAAs and using PFOA and PFOS as examples.

PFAS Treatment Options for Soil & Groundwater
Crimi, M.
NEWMOA PFAS Treatment & Remediation Webinar, 11 slides, 2016

This presentation summarizes the challenges associated with treatment of PFAS-contaminated soil and groundwater and describes potential viable PFAS remediation approaches.

Per- and Polyfluoroalkyl Substances (PFASs): Chemistry, Occurrence, Regulation, Mobility and Remediation
DiGuiseppi, B. and M. Danon-Schaffer.
RemTech 2016: Remediation Technologies Symposium, Banff, AB, Canada. 26 slides [Abstract]

Technology tests involving oxidation, sorption, thermal, and biological treatment from researchers in academia and industry are reviewed and evaluated in terms of demonstrated effectiveness and applicability (slides 15-25).

Pilot-Scale Field Demonstration of a Hybrid Nanofiltration and UV-Sulfite Treatment Train for Groundwater Contaminated by Per- And Polyfluoroalkyl Substances (PFASs)
Liu, C.J., G. McKay, D. Jiang, R. Tenorio, J.T. Cath, C. Amador, C.C. Murray, J.B. Brown, H.B. Wright, C. Schaefer, C.P. Higgins, C. Bellona, and T.J. Strathmann.
Water Research 205:117677(2021) [Abstract]

A pilot-scale hybrid nanofiltration (NF) and ultraviolet (UV)-sulfite treatment train was field-tested to remediate 12 PFASs detected in AFFF-impacted groundwater at a DoD installation. NF rejection was consistently ≥ 95% over 30-days when operating at 90% total permeate recovery for most detected PFAS. Rejection of short-chain PFSAs by NF decreased when recoveries increased from 90 to 97%. Tests with a reverse osmosis (RO) membrane showed ≥ 99% rejection of all PFAS regardless of increasing recovery. UV treatment of the NF reject water following 90% permeate recovery resulted in variable destruction of individual PFAS. Rates were dependent on pH and the identity and concentration of the UV photosensitizer. PFCA degradation rates were greater than those measured for PFSAs and PFAA precursors and were independent of perfluoroalkyl chain length. In contrast, PFSA degradation rates increased with increasing chain length. Consistent levels of PFAS degradation by UV-sulfite were observed during a 30-day demonstration experiment in NF reject water amended with 10 mM sulfite and adjusted to pH 11.2. Collectively, > 75% of the detected PFAS mass in the NF reject was destroyed after 4 h of UV treatment and increased to > 90% after 8 h of treatment. An analysis of electrical energy inputs for the hybrid NF/UV-sulfite treatment train showed energy per order magnitude requirements ranging from ≤ 13.1 kWh/m³ for PFCAs and 14.1 kWh/m3 for PFOS to values > 100 kWh/m³ for more recalcitrant short-chain PFSA analogues.

Physico-Chemical Processes for the Treatment of Per- and Polyfluoroalkyl Substances (PFAS): A Review
Nzeribe, B.N., M. Crimi, S.M. Thagard, and T.M. Holsen.
Critical Reviews in Environmental Science and Technology 49(10):866-915(2019) [Abstract]

This article evaluates and compares the strengths and limitations of available physico-chemical treatment techniques for destruction of PFAS. A comparative assessment based on effectiveness (extent of degradation and defluorination) and efficiency (rate, cost, and energy use) revealed that electrochemical oxidation, advanced reduction processes and plasma-based technology exhibited the best potential towards overall process efficiency. Sonolysis and heat-activated persulfate had the highest energy demand while photochemical oxidation was the most ineffective method.

The Price of Really Clean Water: Combining Nanofiltration with Granular Activated Carbon and Anion Exchange Resins for the Removal of Per- And Polyfluoralkyl Substances (PFASs) in Drinking Water Production
Franke, V., M. Ullberg, P. McCleaf, M. Walinder, S.J. Kohler, and L. Ahrens.
ACS ES&T Water [Published online 29 January 2021 prior to print]

A six-month nanofiltration (NF) pilot was conducted at a drinking water treatment plant in Sweden. NF removed >98% of PFAS and met other water quality targets, such as the removal of uranium-238, dissolved organic carbon, and mineral hardness from the raw water. The concentrate from the pilot plant was treated with two different granular activated carbon (GAC) materials and two different anion exchange (AIX) resins in column tests. AIX exhibited superior performance in PFAS removal compared to GAC. Treatment costs were found to be largely dependent on the PFAS drinking water treatment goals and concentrate discharge requirements.

Recommendation on Perfluorinated Compound Treatment Options for Drinking Water
New Jersey Drinking Water Quality Institute, Treatment Subcommittee, 13 pp, 2015

This report describes PFOA, PFOS, and PFNA treatment options for municipal utilities.

Remediation of Poly- and Perfluoroalkyl Substances (PFAS) Contaminated Soils - To Mobilize or to Immobilize or to Degrade?
Bolan, N., B. Sarkar, Y. Yan, Q. Li, H. Wijesekara, K. Kannan, D.C.W. Tsang, M. Schauerte, J. Bosch, H. Noll, Y.S. Ok, K. Scheckel, J. Kumpiene, K. Gobindlal, M. Kah, J. Sperry, M.B. Kirkham, H. Wang, Y.F. Tsang, D. Hou, and J. Rinklebe.
Journal of Hazardous Materials 401:123892(2021) [Abstract]

This review presents remediation of PFAS contaminated soils through manipulation of their bioavailability and destruction using mobilizing and immobilizing agents. Mobilizing amendments (e.g., surfactants) can be applied to facilitate the removal of PFAS though soil washing and phytoremediation, and complete destruction through thermal and chemical redox reactions. Immobilizing amendments (e.g., activated carbon) are likely to reduce the transfer of PFAS to food chain through plant and biota uptake and leaching to potable water sources.

Removal and Destruction of PFAS and Co-Occuring Chemicals from Groundwater via Extraction and Treatment with Ion Exchange Media, and On-Site Regeneration, Distillation, and Plasma Destruction
Hagelin, N., Y. Aly, K. Chick, J. Heath, E. Thompson, C. Vowles, and J. Kornuc. | ESTCP Project ER18-5015, 2,902 pp, 2022 [Final Report] [Executive Summary]

Results and conclusions of a pilot study conducted at former Pease Air Force Base in Portsmouth, New Hampshire, are presented in this report. The purpose of the study was to further prove the effectiveness and develop scale-up criteria for integrating a PFAS treatment and destruction technology into existing groundwater treatment systems. The effectiveness of four PFAS Treatment and Destruction Trains (ion exchange resin, resin regeneration, distillation of spent regenerant, and low energy plasma destruction) of concentrated PFAS waste was evaluated. Performance assessment included pretreatment success criteria, resin performance, reuse and regeneration of resin, and plasma destruction. Findings were used to develop a cost model for regenerable IX/distillation/plasma scenario to compare to other currently available technologies.(YouTube Video of the DMX Plasma System)

Treatment Technologies and Methods for Per- and Polyfluoroalkyl Substances (PFAS)
Interstate Technology and Regulatory Council (ITRC), 4 pp, 2022

This overview of remedial technologies and methods for PFAS treatment in solids (soil, sediment) and liquids (groundwater, leachate, surface water) identifies both recognized and developing technologies and describes challenges and limitations for each.

A Review of Emerging Technologies for Remediation of PFASs
Ross, I., J. McDonough, J. Miles, P. Storch, P.T. Kochunarayanan, E. Kalve, J. Hurst, S.S. Dasgupta, and J. Burdick.
Remediation Journal 28(2):101-126(2018)

Remedial technologies that are adsorptive or destructive are considered for both soils and waters, with challenges to their commercial application outlined. Ex situ technologies for water treatment and treatment train strategies are also discussed.

A Review of the Emerging Treatment Technologies for PFAS Contaminated Soils
Mahinroosta, R. and L. Senevirathna.
Journal of Environmental Management 255:109896(2020) [Abstract]

A comprehensive evaluation of existing and emerging technologies for remediating PFAS-contaminated soils was conducted with guidance on which approach to use in different contexts. The functions of all remediation technologies, their suitability, limitations, and the scale applied from laboratory to the field are presented as a baseline for understanding the research need for treatment in soil environments. Methods discussed include immobilization, soil washing, thermal treatment techniques, chemical oxidation, ball milling, and electron beams.

Six Pilot-Scale Studies Evaluating the In Situ Treatment of PFAS in Groundwater
McGregor, R.
Remediation 30(3):39-50(2020)

Results are presented for six 18-month field studies conducted in a contaminated unconfined sand aquifer to determine if hydrogen peroxide (H₂O₂), sodium persulfate (Na₂S₂O₈), powdered activated carbon (PAC), colloidal activated carbon (CAC), an ion-exchange resin (IER), or biochar attenuate dissolved-phase PFAS in the presence of petroleum hydrocarbons.

Treatment Mitigation Strategies for Poly- and Perfluoroalkyl Substances
Dickenson, E. and C. Higgins.
Water Research Foundation, Project #4322, 123 pp, 2016

This report looks at the efficacy of various treatment technologies available to drinking water utilities for treatment of source water containing PFASs. (Summary)

Treatment of Poly- And Perfluoroalkyl Substances in U.S. Full-Scale Water Treatment Systems
Appleman, T., C. Higgins, O. Quinones, B. Vanderford, C. Kolstad, J. Zeigler-Holady, and E. Dickenson.
Water Research 51:246-255(2014) [Abstract]

Concentrations of PFASs in 18 raw drinking water sources and 2 treated wastewater effluents were measured and evaluated in 15 full-scale treatment systems for the attenuation of PFASs in water treatment utilities across the U.S. An LC/MS-MS method was used to enable measurement of a suite of 23 PFASs to determine the relative PFAS removal effectiveness of the different treatment technologies. Additional information: Slides

Treatment Technologies for Aqueous Perfluorooctanesulfonate (PFOS) and Perfluorooctanoate (PFOA): A Critical Review with an Emphasis on Field Testing
Espana, V.A.A., M. Mallavarapu, and R. Naidu.
Environmental Technology & Innovation 4:168-181(2015) [Abstract]

A review of existing methods for removing PFOS and PFOA from wastewaters emphasizes processes that seem to show promise for the development of practical industrial-scale remediation technologies.

Treatment Train Approaches for the Remediation of Per- and Polyfluoroalkyl Substances (PFAS): A Critical Review
Lu, D., S. Sha, J. Luo, Z. Huang, and X.Z. Jackie. Journal of Hazardous Materials 386:121963(2020) [Abstract]

Since 2015, treatment train processes have been used to effectively achieve in situ remediation of PFAS. This review provides new insight into recently reported treatment train studies selected from ~150 different publications on PFAS remediation and discusses their innovative designs, remediation performances, present limits, and possible improvements. A new design is proposed that consists of three individual technologies, nanofiltration, electrochemical anodic oxidation, and electro-Fenton degradation, to maximize the economic and environmental benefits of PFAS remedial measures.

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Adsorption

75 Million Gallons Later — 5 Year Update on World's First Regenerable Resin System Treating PFAS
McKeown, P., E. Houtz, and N. Bolea. | AEHS Foundation 32nd Annual International Conference on Soil, Water, Energy and Air, 20-23 March, San Diego, CA, 22 slides, 2023.

Side-by-side pilot tests were conducted in 2016, followed by the design and installation of a PFAS Treatment plant utilizing SORBIX RePURE Regenerable Ion Exchange Resin as part of ongoing response activities to remove PFAS-impacted groundwater at the former Pease Air Force Base in New Hampshire. The 200-gpm capable system was designed to meet the primary project objective of producing treated water with combined PFOS+PFOA concentrations below the 70 ng/l Health Advisory Level. In the five years since commissioning, the PFAS remediation system has treated >75 million gals of groundwater, with a total average influent PFAS concentration of 60 µg/l. The effluent quality from the IX resin system was consistently non-detect for PFOS and PFOA, readily achieving compliance with the 70 ng/l target. Twenty-four successful resin regenerations have been performed to date, with no decrease in sorptive capacity. Operational modifications were conducted to address, and correct minor challenges with the distillation system, and regenerant recovery and super-loading processes have proven successful. The original SuperLoading media is still operational, having removed and concentrated greater >99.99% of the recovered PFAS mass, and no PFAS waste has been hauled offsite to date. The system currently operates at concentration factors of > 1 million to one, meaning less than a gallon of waste is generated for every million gallons of 60 µg/l PFAS-impacted water treated.

Adsorption of Perfluorooctane Sulfonate (PFOS) and Perfluorooctanoic Acid (PFOA) by an Organically Modified Palygorskite
Espana, V.A.A., B. Sarkar, and R. Naidu.
CleanUp Conference 2015, 13-16 September, Melbourne, Australia, P8, 462-463 [517-518 in PDF file count], 2015

This study assesses the adsorption of PFOS and PFOA by an organically modified palygorskite.

Adsorption of Traditional and Emerging Perfluoroalkyl Substances by Powdered Activated Carbon
Sun, M., L.-A. Dudley, M. Strynar, A. Lindstrom, and D. Knappe.
Abstracts: American Chemical Society Conference, Philadelphia, August 2016 [Longer abstract]

The objective of this research was to identify parameters that control the adsorption of PFASs, including 10 traditional PFASs (7 carboxylic acids, 3 sulfonic acids) and 6 emerging perfluoro(poly)ethers, by a thermally activated wood-based powdered activated carbon. The project also evaluated the potential for using the relationship between the number of perfluorinated carbon atoms and the octanol/water partition coefficient (log D) as a tool to predict the adsorbability of emerging PFASs by activated carbon.

Adsorption Properties of Modified Natural Materials for the Removal of Perfluorochemicals in AFFF Wastewater
Kambala, V., F. Han, T. Kandasamy, and R. Naidu.
Proceedings of the 19th World Congress of Soil Science – Soil Solutions for a Changing World – Brisbane, Queensland, 1-6 August 2010. International Union of Soil Sciences, 3 pp, 2010

The authors investigated the sorption behavior of MatCARE™ using batch experiments with technical-grade Ansulite (a new aqueous film-forming foam product) and AFFF wastewater.

Adsorptive Removal of Emerging Polyfluoroalky Substances F-53B and PFOS by Anion-Exchange Resin: A Comparative Study
Gao, Y., S. Deng, Z. Du, K. Liu, and G. Yu.
Journal of Hazardous Materials 323(Pt A):550-557(2017) [Abstract]

Researchers evaluated the anion-exchange resin IRA67.

Collaborative Pilot-Scale Evaluation of Granular Activated Carbon (GAC) and Ion Exchange Medias for Removal of PFAS From Groundwater (See times 35:30-1:04:22)
Redding, A., J. Guyer, R. Jaeger, S. Coleman, and C.R. Powley.
18th Annual EPA Drinking Water Workshop, 30 August-1 September, 2021

A pilot test was conducted to compare the PFAS removal performance of bituminous and sub-bituminous granular activated carbon to ion exchange media (macro-type and gel-type). The pilot study was scaled to accurately match the hydraulic loading rate and predict the full-scale performance via the bed depth-service time model. PFAS breakthrough was speciated not only on a compound by compound basis but also by the branched versus linear isomers, showing less selectivity of branched isomers by 10 for GAC and IX. Several hypotheses are proposed for this outcome, and the impact of molecular size and polar/nonpolar surface areas is discussed. The results were used to generate a cost comparison of media to guide future technology selection.

Colloidal Activated Carbon for In Situ Remediation of PFAS: A Review of Multiple Case Studies
Thoreson, K., M. Dooley, and P. Erickson.
National Ground Water Association Groundwater Week, 3-5 December, Las Vegas, NV, abstract only, 2019 [Abstract]

Multiple field sites have been treated with a single application of colloidal activated carbon to address PFAS contamination and comingled contaminants. In each case, amendments were applied under low-pressure conditions using direct-push technology. Monitoring at all sites is ongoing, with current data ranging from three months to over two years, and has included analysis of PFOS, PFOA, shorter chain PFASs, and co-contaminant concentrations. The case studies indicate that the in situ application of colloidal activated carbon offers a new strategy to address the risk associated with PFAS contamination at a low cost.

Colloidal Activated Carbon Used to Reduce PFAS and Chlorinated Solvent Concentrations in Groundwater to Below Detection Limits at a Michigan Army National Guard Site
Northington, C. | 29th Annual David S. Snipes/Clemson Hydrogeology Symposium, 21 October, Clemson, SC, 23 minutes, 2021

The presentation reviews project design considerations, field activities, and post-application data, following a colloidal activated carbon application to treat chlorinated solvents and PFAS in groundwater at the Camp Grayling site. The site was impacted by chlorinated solvents from historical operations at the facility. After the potential for PFAS contamination from onsite firefighting training activities became known, the Michigan Department of Military and Veteran's Affairs tested for PFAS. PFAS, co-mingled with the chlorinated solvent plume migrating towards the property boundary, was found above EPA's drinking water advisory limit. An in situ reactive barrier application of colloidal activated carbon was selected because of the expected rapid removal of PFAS from the dissolved mobile phase, well-established uses for chlorinated solvent sites, and due to its expected lower total project costs when compared to the operation of a mechanical system. The project area was treated with a single colloidal activated carbon application to address groundwater impacts. Mass flux and predictive competitive sorption modeling were utilized to determine the appropriate amount of colloidal activated carbon required. The remediation solution was applied under low-pressure conditions using direct-push technology with separate soil cores and well monitoring to determine distribution. Monitoring results demonstrated the distribution of the colloidal activated carbon was achieved. Post-application groundwater monitoring results demonstrate that PFAS and chlorinated solvent concentrations were reduced to below detection limits within one month and were sustained for over a year and a half.

Cottage Grove Pilot Study Final Report
Stantec Institute for Water Technology & Policy for Minnesota Pollution Control Agency, 90 pp, 2022

A pilot-scale study tested five different treatment column configurations for treating PFAS-contaminated groundwater at Cottage Grove Well #3 in the East Metro of Minneapolis-St. Paul, MN. One column evaluated granular activated carbon (GAC) media to treat raw water, two evaluated ion exchange (IX) resins to treat raw water, and two evaluated the same IX resins to treat GAC column effluent and investigate the potential for GAC-IX mixed media treatment. Significant fouling occurred in the IX columns treating raw water within weeks of startup. Results were complicated by potential fouling acceleration from water contact with the atmosphere before treatment. The fouling affected the GAC column to a lesser degree, while the IX columns treating GAC effluent did not exhibit any noticeable fouling. Pretreatment using manganese dioxide media was added to the pilot scope to reduce influent water iron and manganese concentrations. Although the pilot was run for ~1 1/2 years, the use of sample ports placed along the media column accelerated treatment to imitate a longer treatment runtime. Results showed significant advantages to IX treatment compared to GAC treatment for perfluorosulfonic acids (PFBS, PFHxS, and PFOS), which comprise the majority of the health index value for the pilot source water and several other water sources in the East Metro. Neither GAC nor IX treatment showed significant treatment capacity for short-chain perfluorocarboxylic acids (PFBA) and showed similar mid-level treatment capacity for long-chain perfluorocarboxylic acids (PFOA). Breakthrough of various PFAS compounds were used to calculate the breakthrough of the overall Health Index to predict approximate media life. Twenty-year net present value estimates for facilities of 1.0 million gal/day, 4.5 million gals/day, and 10 million gals/day flow rates were calculated considering building capital costs and facility operation and maintenance costs.

Constructing the Nation's Largest Ion Exchange PFAS Water Treatment Plant
Hakes, K. | Northeast Conference on The Science of PFAS: Public Health & The Environment, 5-6 April, Marlborough, MA, 23 slides, 2022

Several dozen wells in Orange County were temporarily taken out of service to meet California's advisory Response Levels for PFAS in drinking water. The Orange County Water District (OCWD) initiated a robust response to address PFAS, including designing and constructing treatment facilities for local water agencies to restore the impacted drinking water supply. OCWD, the Yorba Linda Water District, and several companies worked closely together to construct the nation's largest ion exchange PFAS water treatment plant. The treatment plant will treat up to 25 million gals of water a day. The webinar provides an overview of the project from early collaboration through construction, start-up, and operation, including lessons learned and key factors that led to its success. Additional information: Presentation, Yorba Linda Water District website

AFFF Contaminated Soil and Water: Risks, Remedial Options
Naidu, R.
Parliament of Victoria [Australia]: Inquiry into the CFA Training College at Fiskville. Transcript and 48 slides, 19 Oct 2015

This presentation describes the use of MatCARE™, an amine-modified clay, at AFFF-contaminated sites in Australia. Additional information: Transcript, Slides

Development of Effective Removal Methods of PFCs (Perfluorinated Compounds) in Water by Adsorption and Coagulation
Senevirathna, T.M.L.D.S., Ph.D. dissertation, University of Kyoto, Japan, 177 pp, 2010

The work included examination of the ability of six synthetic resins and GAC to remove PFCs from water in addition to an evaluation of organic coagulants.

The Effect of Heterogeneity on the Distribution and Treatment of PFAS in a Complex Geologic Environment
McGregor, R. and L. Benevenuto. | Frontiers in Environmental Chemistry 2:729779(2021)

The effect of heterogeneity on colloidal activated carbon (CAC) distribution and subsequent PFAS treatment at a site with a multiple-aquifer system was evaluated in a pilot study. Geology varied from silty sand to sand to fractured bedrock, with all three units being impacted by PFAS and BTEX). Parameters evaluated included CAC distribution and subsequent PFAS and BTEX treatment. Groundwater sampling indicated that PFAS contamination was effectively treated to below their respective reporting limits during the one-year test in both the silty sand and sand aquifers. PFAS in the fractured rock aquifer showed a different treatment profile with longer carbon-chain PFAS attenuating preferentially than the shorter carbon-chain PFAS. Results suggest that competitive sorptive reactions occurred on the CAC within the fractured rock. Analysis of the unconsolidated aquifer materials determined that direct push injection of the CAC effectively delivered it to the target injection zones, with post-injection total organic carbon (TOC) concentrations increasing by up to three orders of magnitude compared to pre-injection TOC concentrations. Heterogeneity impacted the CAC distribution, with higher hydraulic conductivity zones receiving more CAC mass than lower hydraulic conductivity zones.

Efficient Sorption and Removal of Perfluoroalkyl Acids (PFAAs) from Aqueous Solution by Metal Hydroxides Generated In Situ by Electrocoagulation
Lin, H., Y. Wang, J. Niu, Z. Yue, and Q. Huang.
Environmental Science & Technology 49(17):10562-10569(2015) [Abstract]

Four metal hydroxide flocs generated in situ by electrocoagulation in deionized water were evaluated for their ability to remove PFOS and perfluorocarboxylic acids (C4 through C10).

Electrocoagulation Mechanism of Perfluorooctanoate (PFOA) on a Zinc Anode: Influence of Cathodes and Anions
Wang, Y., H. Lin, F. Jin, J. Niu, J. Zhao, Y. Bi, and Y. Li.
Science of the Total Environment 557-558:542-550(2016) [Abstract]

Batch experiments were conducted to investigate the effects of different cathode materials and anions on PFOA removal by electrocoagulation using a zinc anode.

Fluorochemicals in AFFF Contaminated Sites: Environmental Fate, Toxicity and Treatment
Liu, J., J. Paquin, and G. Zhong.
2016 RPIC Federal Contaminated Sites (FCS) National Workshop, 25-27 April, 43 slides, 2016

Challenges in addressing PFAS contamination are described and illustrated by two case studies: one involving an underground storage tank containing AFFF, and the other the cleanup of surface and subsurface liquids (petroleum and AFFF) remaining after a crude oil train derailment and fire.

Immobilization of PFASs Using Activated Carbon and Aluminum Hydroxide
Birk, G.M.
Emerging Contaminants Summit, March 1-2, 2016, Westminster, Colorado. 36 slides, 2016

This presentation reports on the results of the use of RemBind™ and RemBind Plus™ on soils contaminated with PFASs at two airport fire training grounds in Australia.The presentation also introduces PerfluorAd, a cationized cellulose-based raw material that is designed to bond with and precipitate PFASs in aqueous media. Additional information: Longer abstract; Rembind poster; Rembind patent; PerfluorAd poster.

In Situ Sequestration of Perfluroalkyl Substances using Polymer-Stabilized Powedered Activated Carbon
Liu, C., J. Hatton, W.A. Arnold, M.F. Simcik, and K.D. Pennell.
Environmental Science & Technology [Published online 7 May 2020 prior to print]

The objective of this study was to evaluate the in situ delivery and sorptive capacity of an aqueous suspension containing powdered activated carbon (PAC) stabilized with polydiallyldimethylammonium chloride (polyDADMAC) to remove PFOA and PFOS from water. Batch studies demonstrated adsorption of PFOA and PFOS by polyDADMAC-stabilized PAC, yielding Freundlich adsorption coefficients of 156 and 629 L/g^-n, respectively. In columns packed with 40-50 mesh Ottawa sand, injection of a 1000 mg/L PAC + 5000 mg/L polyDADMAC suspension created a sorptive region that increased PFOA and PFOS retention by three orders of magnitude relative to untreated control columns, consistent with the mass of retained PAC. Experiments conducted in a heterogeneous aquifer cell further demonstrated the potential for stabilized-PAC to be an effective in situ treatment option for PFAS-impacted groundwater.

The In Situ Treatment of PFAS Within Porewater at the Air-Water Interface of a PFAS Source Zone
McGregor, R. | Remediation 33(4):265-278(2023)

A study evaluated the use of colloidal activated carbon (CAC) to treat dissolved PFAS at the air-water interface within the source zone using direct push technology and a dense injection grid that targeted the interface between the air and groundwater. PFAS within the porewater and groundwater were collected using a series of nine lysimeters installed within the vadose and saturated water columns. Six PFAS were detected in the porewater and groundwater, including PFBA, PFPeA, PFHxA, PFHpA, PFOA, and PFNA. Before treatment, detectable PFAS concentrations within the pore and groundwater. Following injection of the CAC, porewater and groundwater monitoring for PFAS was conducted ~3, 6, 9, 12, and 18 months postinjection. Results indicated that the PFAS within the porewater and groundwater at and near the air-water interface was effectively attenuated over the 1.5-year monitoring program. PFAS concentrations were below the method detection during the 18-month sampling event at concentrations of ≤ 55ng/L. Examining aquifer cores in the zone of injection indicated that the total organic carbon concentration of the aquifer increased by five orders of magnitude postinjection, with 97% of the samples collected within the target injection area containing activated carbon, indicating that the CAC was successfully delivered into the source zone.

The In Situ Treatment of TCE and PFAS in Groundwater Within a Silty Sand Aquifer
McGregor, R. and Y. Zhao | Remediation 31(2):7-17(2021)

At a former industrial site, shallow groundwater contained concentrations of TCE, cis-1,2-DCE, and VC as high as 985, 258, and 54 µg/L, respectively. Groundwater also contained maximum concentrations of the following PFAS: 12,800 ng/L perfluoropentanoic acid, 3,240 ng/L perfluorohexanoic acid, 795 ng/L perfluorobutanoic acid, 950 ng/L perfluorooctanoic acid, and 2,140 ng/L perfluorooctanesulfonic acid. A combination of remedial approaches was selected, with adsorption being used for PFAS and adsorption, chemical reduction, and anaerobic biodegradation used for the chlorinated ethenes. Two years of groundwater sampling indicated that the detected PFAS were treated to either their detection or below the analytical detection limit over the monitoring period. Post-injection results for the chlorinated ethenes indicated that the concentrations decreased by an order of magnitude within 4 months, with TCE decreasing to below the analytical detection limit over the 2-year monitoring period. Cis-1,2-DCE, and vinyl chloride concentrations decreased by over 99% within 8 months of injections, remaining at or below these concentrations during the 2-year monitoring period. Analyses of Dehalococcoides, ethene, and acetylene over time suggest that microbiological and reductive dechlorination were occurring in conjunction with adsorption within the aquifer.

Ionic Fluorogels for Remediation of Per- and Polyfluorinated Alkyl Substances from Water
Kumarasamy, E., I.M. Manning, L.B. Collins, O. Coronell, and F.A. Leibfarth.
ACS Central Science 6(4):487-492(2020)

An ionic fluorogel resin was developed to remove a chemically diverse mixture of PFAS from water effectively. The resin has demonstrated rapid removal of PFASs with high affinity and selectivity in the presence of nonfluorous contaminants commonly found in groundwater. The material can be regenerated and reused multiple times. The ionic fluorogels were demonstrated to be effective adsorbents in removing 21 legacy and emerging PFASs from settled water collected at the Sweeney Water Treatment Plant in Wilmington, North Carolina.

Lessons Learned from 5-Years of Full-Scale PFAS Plume Management and Liquid GAC Groundwater Treatment
Pohlmann, D. and R. Morrish. | Global Enviro Summit 4-6 April, Charlotte, NC, abstract only, 2022

A groundwater pump and treat system was activated to capture a PFOA/PFOS plume at a former DoD fire training area. Historical remedial actions included SVE and in situ anaerobic biodegradation. The extracted groundwater was treated using two 20,000-lb liquid granular activated carbon (LGAC) vessels operated in series to below PFOA and PFOS discharge objectives of 0.04 and 0.02 µg/L, respectively. To date, the system has treated ~700 million gals of groundwater, removed 37.7 lbs of PFOA/PFOS, and 23 LGAC exchanges have been conducted. When the pump and treat system was designed and installed, much was unknown about the plume behavior of PFOA and PFOS and the use of LGAC to treat these compounds. Additional delineation showed that the PFOA/PFOS plume is concentrated near the water table surface. Passive Flux meters were deployed to evaluate their applicability to PFOA/PFOS measurement and their correlation to groundwater concentrations and mass removed by the pump and treat system. Samples analyzed by the total oxidable precursor assay indicated that individual PFOA/PFOS compounds account for ~30% of total PFAS impact on the LGAC system. More information

Lessons Learned on Vermont POET Installations and Operations for Residences Impacted by PFASs
NEWMOA PFAS Treatment & Remediation Webinar, 8 slides, 2016

Provides an overview of experience with installing and maintaining point-of-entry treatment (POET) systems in households in North Bennington, Vermont.

Modeling Pilot-Scale GAC PFAS Adsorption for the Simulation of Full-Scale Performance and Costs
Burkhardt, J., C. Vandermeyden, N. Burns, D. Mobley, C. Patterson, R. Khera, et al.
AWWA Water Quality Technology Conference, 3-7 November, Dallas, TX, 2019

This presentation discusses modeling PFAS removal with granular activated carbon and other resources associated with PFAS removal from drinking water. The presentation specifically discusses the process of extending pilot data into full-scale predictions of bed replacement frequency and costing efforts as well as information associated with the treatability database. Download presentation

Molecular Design of Effective and Versatile Adsorbents for Ex Situ Treatment of AFFF-Impacted Groundwater
Michalsen, M., J.A. Field, E. Christie, M. Khazaee, and C. Ng. SERDP Project ER18-1417, 31 pp, 2019

Results of this limited-scope project confirmed the potential of protein-based sorbents for PFAS remediation by identifying, through a complementary model-experiment approach, proteins that associate strongly with both long- and short-chain PFAS.

Performance Evaluation: Removal of Perfluorochemicals (PFCs) with Point-of-Use (POU) Water Treatment Devices
Olsen, P.C. and D.J. Paulson.
Minnesota Department of Health, 140 pp, 2008

The Minnesota Department of Health commissioned a study that evaluated the ability of 11 commercially available POU water treatment devices to remove PFCs from groundwater sourced from community and non-community public water supplies and private wells.

Pilot Test Results for Ion Exchange Resin and Granular Activated Carbon to Treat Groundwater Impacted with Per- And Polyfluoroalkyl Substances La Habra Heights County Water District Water Supply Well #10
GSI Environmental Inc. for the Water Replenishment District of Southern California, 2,216 pp, 2021

A pilot test was conducted to evaluate the performance and life cycle costs for four ion exchange (IX) resins and four granular activated carbons (GAC) to treat groundwater impacted by PFAS, including PFOA and PFOS, from water sourced from La Habra Heights County Water District Water Supply Well #10. Empty bed contact time (EBCT) of the GAC test columns matched a typical full-scale GAC EBCT (10 min), while a shorter EBCT (1.2 min) was selected for IX resin. The pilot skid was monitored daily, and flow rates were adjusted periodically to correspond with the design pilot test EBCTs of the GAC and IX media. Influent water was pretreated with a 5 µm cartridge filter to prevent fouling. While the pilot skid generally operated effectively over the pilot test duration, periodic well shutdowns and insufficient well supply pressure caused periods of downtime throughout the test. PFOA was consistently the driver for media changeout. Only the PFA694E resin allowed PFOA breakthrough by the end of the test; no effluent sample for any GAC had detectable PFOA concentrations. A linear extrapolation approach was applied to the GAC and the IX media effluent breakthrough curves to estimate 10 ng/L PFOA breakthrough bed volumes. Based on the results, PSR2 Plus was determined to be the best performing IX resin, and the F400 GAC is anticipated to treat the highest volume of water prior to breakthrough at the 10 ng/L RL for PFOA. The cost-effectiveness of all tested media was evaluated using life cycle cost analysis that involved development cash flows to represent capital and operation and maintenance costs using key assumptions to simplify the cost estimation process. The AV1240LDX GAC was the most cost-effective media for removing PFAS with a cost of $2,920,000, while the PRS2 Plus was second at a cost of $2,996,000.

PFAS: Advocating for Approval of the Best Treatment Technologies in an Evolving Regulatory Climate
MacDonald, S.J. and F. Wilson. | American Institute of Professional Geologists Michigan Section Workshop, 15-17 June, virtual, 42 minutes, 2021

In 2018, the Michigan PFAS Action Response Team sampled water supplies for communities, schools, childcare providers, and tribes for PFAS. Among all tested sites, two (one an elementary school) had test results exceeding EPA's Lifetime Health Advisory (LHA) level of 70 ng/L PFOA and PFOS. This case study describes the steps taken to select the best available treatment technology for the small water supply system servicing the school. A granular activated carbon (GAC) adsorption treatment system was designed to provide PFAS-free drinking water to the school. However, considering the Michigan Department of Environment, Great Lakes, and Energy's subsequent effort to develop limits for seven telomers, including levels of PFOS and PFOA, lower than the LHA, additional treatment technologies were reviewed to find one that would be even more effective than GAC. Single-use ion exchange (IX) media stood out as a more effective treatment alternative with minimal operating costs. The IX system is currently operating, and an extensive sampling program is being implemented. This presentation includes an account of the process used to obtain technology approval, current system data, and lessons learned.

PFAS Phase I Pilot-Scale Treatment Study Final Report
Pannu, M. and M. Plumlee for the Orange County Water District, 41 pp, 2021

A pilot-scale treatment study was conducted to test different types of adsorbent media, including granulated activated carbon (GAC), ion exchange (IX) resins, and alternative adsorbents to remove PFAS from affected wells within the Orange County Groundwater Basin. Fourteen different media were evaluated via pilot testing for 13 months using empty bed contact times (EBCTs) (10 min for GAC, 2 min for IX, and 2 to 5 min for alternative adsorbents). All products initially demonstrated removal of PFOA to below detection limit (2 ng/L); media performance was then compared based on time to reach initial breakthrough (>2 ng/L) and significant breakthrough (defined as 60% exhaustion when effluent concentration is ~60% of influent concentration). Breakthrough occurred slower for PFOS than PFOA for all IX and alternative adsorbents that showed no PFOS breakthrough after 13 months (for IX) and 11 months (for alternative adsorbents). PFOS breakthrough was also slower than PFOA for GAC but faster compared to the other media. For short-chain PFAS, PFBS removal was sustained longest by IX, followed by alternative adsorbents and GAC with the shortest breakthrough time.

PFAS Treatment and Investigation at a Former Chromium Plating Facility - A Case Study
Hoare, B. | Midwestern States Environmental Consultants Association Virtual Environmental Conference, 2-3 and 9-10 December, abstract only, 2020

Past releases of process solutions and waste-treatment residuals from a former chrome plating facility caused elevated concentrations of hexavalent chromium (Cr⁺⁶) and nickel (Ni) in site soil and groundwater. To address contamination, groundwater had been continuously pumped from four extraction wells for treatment at the Kalamazoo POTW. Samples from the outfall at the former plating facility and identified PFOS concentrations in excess of 8,000 ng/L. As a result, the groundwater extraction system was shut down in June 2018. An emergency carbon and ion exchange PFAS treatment system was installed (functional within one month) for the existing extraction well network to treat PFAS from the effluent and address challenges of matrix interference from the Ni and Cr⁺⁶, sequestrants from the former plating process, and solids from the groundwater. Additional information: Presentation

PFAS Treatment Trials with Granulated Activated Carbon
Galbraith, F., D. McMillan, M. Edwards, R. Pennell, and M. Goulden.
REMTECH 2020: The Remediation Technologies Symposium, 14-15 October, Virtual Meeting, abstract, 2020

Source control treatment of surface water containing hydrocarbons, PAHs, metals, and PFAS contamination was conducted within a retention pond in the Fire Fighting Training Area of Canadian Forces Base Comox, Lazo, in British Columbia. Granulated activated carbon (GAC) and components of an existing water treatment system were used to treat PFAS-impacted surface water within the pond and from a recent spill of a newer formulation of aqueous film-forming foam at a separate base area. In addition, advanced oxidation was evaluated on samples of surface water. Results from the treatment of PFAS with GAC and advanced oxidation are presented along with considerations for improving performance and optimizing the long-term treatment of these compounds at the site. Additional information: Presentation

Pilot-Scale Injection of Colloidal Activated Carbon for PFAS Immobilization at a Contaminated Field Site
Fagerlund, F., G. Niarchos, L. Ahrens, D. Berggren Kleja, J. Bergman, A. Larsson, G. Leonard, J. Forde, J. Edvinsson, K. Holmstrom, H. Persson, and L. Gottby.
European Geosciences Union General Assembly, 4-8 May, Virtual, poster, 2020

In situ stabilization of PFAS by injection of colloidal activated carbon (CAC, PlumeStop^®) was investigated at a contaminated site in Sweden. CAC was injected to create a defined zone where PFAS from the contaminant plume would sorb to CAC and be removed from the flowing groundwater, similar to a permeable reactive barrier. The effect of the injected CAC was studied by monitoring PFAS concentrations in the groundwater upgradient and downgradient, as well as within the CAC barrier before and after injection. The low-pressure injections were designed and adapted to avoid excessive preferential flow of CAC and achieve a good distribution in the intended treatment zone. Preliminary results indicated a strong reduction of all measured PFAS within and directly downgradient of the CAC barrier, which suggests that the installation of the CAC barrier was successful despite a relatively complex geological setting where fast preferential flow paths exist. Monitoring will indicate how the CAC performs over time.

The Promise and Pitfalls of In-Situ Carbon Immobilization of PFAS - Two Case Studies From Michigan
Mankowski, L. | PFAS: Beyond the Theoretical and What's Working Seminar, 27 Feb, Madison, WI, 38 slides, 2020

Performance monitoring testing was conducted for three pilot tests that involved in situ carbon-based stabilization of PFAS. Two pilot tests used biochars in the PFAS source area surrounding a former tannery. In one test area, Bioavailable Absorbent Media (BAM)-Ultra™ was injected into the saturated system. After 7 days, PFOS concentrations in groundwater declined by 19-96%. In the second test area, BAM-X™ biochar was separately mixed into a 10x10 ft area. At 7 days post-mixing, groundwater PFOS concentrations reduced by 97%. At an airfield site, PlumeStop^® and PlumeStop Stout™ were injected into a co-located, low-level PCE plume downgradient of a former fire-training area. Two months post-injection, PFOS and PCE were not detected in downgradient groundwater. Neither amendment tested achieved homogenous distribution when delivered by injection. Performance monitoring is ongoing. Data have not yet demonstrated amendment effectiveness in stabilizing PFAS in soil or groundwater. However, the data will provide long-term, site-specific case studies for consideration in future feasibility studies to address PFAS. Additional information: Camp Grayling Airfield project

Remediation of Perfluorooctane Sulfonate in Contaminated Soils by Modified Clay Adsorbent: A Risk-Based Approach
Das, P., V.A. Arias, V. Kambala, M. Mallavarupu, and R. Naidu.
Water, Air, & Soil Pollution 224(12):1714(2013) [Abstract]

Researchers investigated the removal of PFOS from impacted waters and fixation of PFOS in soils using MatCARE™, a modified clay adsorbent. Additional information: U.S. Patent 9,284,201, Amine Modified Clay Sorbents (2016).

Removal Efficiency of Perfluoroalkyl Substances (PFASs) in Drinking Water: Evaluation of Granular Activated Carbon (GAC) and Anion Exchange (AE) Using Column Tests, and the Effect of Dissolved Organic Carbon
Oestlund, Anna, Master's thesis, Swedish University of Agricultural Sciences, 59 pp, 2015

The removal efficiency of selected PFASs—26 PFASs in a column experiment and 14 PFASs in a batch experiment—from water was evaluated for two treatment techniques: GAC (Filtrasorb 400®) and anion exchange (Purolite A-600). The effect of dissolved organic carbon on removal efficiency was also studied.

Removal of Perfluorinated Compounds by Anion Exchange: Factors Affecting Resin Performance and Regeneration
Perez, Elisa Carolina Arevalo, Master's thesis, North Carolina State University, 114 pp, 2014

Objectives of this research were to (1) assess the effectiveness of a magnetic anion-exchange resin for the removal of seven PFCAs and three PFSAs, and (2) identify regeneration strategies that effectively restore the PFAS uptake capacity of the spent anion exchange resin.

Removal of Perfluorinated Compounds from Ultrapure and Surface Waters by Adsorption and Ion Exchange
Rahman, Mohammad Feisal, Ph.D. thesis, University of Waterloo, 315 pp, 2014

This study assessed the adsorption behavior of perfluoroheptanoic acid (PFHpA), PFOA, and perfluorononanoic acid (PFNA) by four GACs, two anion exchange resins, and two alternative adsorbents.

Removal of Perfluoroalkyl Substances by PAC Adsorption and Anion Exchange: Executive Summary
Dudley, L.-A., E. Arevalo, and D. Knappe.
Water Research Foundation, Project #4344, 5 pp, 2015

Researchers assessed the removal effectiveness of powdered activated carbon adsorption and anion exchange processes on 10 PFASs: PFOA (or C8), PFOS, perfluorobutanoic acid (C4), perfluoropentanoic acid (C5), perfluorohexanoic acid (C6), perfluoroheptanoic acid (C7), perfluorononanoic acid (C9), perfluorodecanoic acid (C10), perfluorobutane sulfonate (PFBS), and perfluorohexane sulfonate (PFHS).

Removal of Perfluoroalkyl Sulfonates (PFAS) from Aqueous Solution Using Permanently Confined Micelle Arrays (PCMAs)
Wang, F., X. Lu, K.M. Shih, P. Wang, and X. Li.
Separation and Purification Technology138:7-12(2014) [Abstract]

A new sorbent with permanently confined micelle arrays was developed and tested for removing PFAS compounds from aquatic solutions.

Removal of Perfluorooctanoic Acid and Perfluorooctane Sulfonate from Wastewater by Ion Exchange
Lampert, D., M. Frisch, and G. Speitel Jr.
Practice Periodical of Hazardous, Toxic, and Radioactive Waste Management 11(1):60-68(2007) [Abstract]

A treatment screening study was performed to investigate activated carbon adsorption, adsorption onto calcium fluoride solids, evaporation, ion exchange, and liquid-liquid extraction for treatment of PFOA and PFOS in wastewater.

Removing Perfluoroalkyl Acids from Potable Reuse Systems Using Carbon Adsorbents: Bench-Scale and Pilot Testing
Inyang, M., E. Dickenson, and M. Velarde.
Abstract: American Chemical Society Conference, Philadelphia, August 2016 [Longer abstract]

This presentation discusses tests at bench and pilot scale of biochar as a potential alternative adsorbent to GAC for its sorption ability for PFOA and PFBA.

Residual Organic Fluorinated Compounds from Thermal Treatment of PFOA, PFHxA and PFOS Adsorbed onto Granular Activated Carbon (GAC)
Watanabe, N., S. Takemine, K. Yamamoto, Y. Haga, and M. Takata.
Journal of Material Cycles and Waste Management 18(4):625-630(2016) [Abstract]

PFASs adsorbed onto GAC during water treatment were thermally treated (700-1000°C) in an N2 gas stream to assess the fate (e.g., volatile escape) of PFASs during thermal regeneration of GAC.

Thermal Mineralization Behavior of PFOA, PFHxA, and PFOS During Reactivation of Granular Activated Carbon (GAC) in Nitrogen Atmosphere
Watanabe, N., M. Takata, S. Takemine, and K. Yamamoto.
Environmental Science and Pollution Research (2015) DOI: 10.1007/s11356-015-5353-2 [Abstract]

The recovery rate of mineralized fluorine and PFC homologues, including short-chained perfluorocarboxylic acids, was determined during thermal reactivation of GAC in N2 atmosphere.

Treatment of Perfluorinated Alkyl Substances in Wash Water Using Granular Activated Carbon and Mixed-Media
Szabo, J., J. Hall, M. Magnuson, S. Panguluri, and G. Meiners.
EPA 600-R-17-175, 44 pp, 2017

This report summarizes the results from testing conducted to evaluate the treatment of large volumes of water containing PFASs, specifically treatment for water contaminated by aqueous film forming foam used in firefighting. The AFFF selected for this study was a product widely used historically, and it contained PFOA and PFOS. Treatment of the AFFF-contaminated water was investigated using Calgon Filtrasorb® 600 GAC and Ziltek RemBind™ mixed media with the goal of reducing the PFAS concentration before disposal of the water (e.g., in a sewer) rather than reducing PFAS concentrations to drinking water advisory levels.

Treatment of Sites Contaminated with Perfluorinated Compounds Using Biochar Amendment
Kupryianchyk, D., S. Hale, G. Breedveld, and C. Cornelissen.
Chemosphere142:35-40(2016) [Abstract]

The sorption behavior of PFOA, PFOS, and PFHxS was examined on activated carbon and two biochars from different feedstocks. In addition, three native PFAS-contaminated soils were treated by mixing activated carbon and biochar into them and observing subsequent leaching results.

Use of Fenton Reagent Combined with Humic Acids for the Removal of PFOA from Contaminated Water
Santos, A., S. Rodriguez, F. Pardo, and A. Romero.
Science of the Total Environment 563-564:657-663(2016) [Abstract]

A hybrid alternative process to heat-activated persulfate was tested at bench scale by adding humic acid and Fenton-like reagent to a 0.1 mM PFOA solution to evaluate PFOA oxidation efficiency.

Use of Strong Anion Exchange Resins for the Removal of Perfluoroalkylated Substances from Contaminated Drinking Water in Batch and Continuous Pilot Plants
Zaggia, A., L. Conte, L. Falletti, M. Fant, and A. Chiorboli.
Water Research 91:137-146(2016) [Abstract]

A study of the application of three strong anion exchange resins (Purolite® A520E, A600E, and A532E) to the removal of traces of PFOA, PFOS, PFBA and PFBS (concentration of hundreds of ng/L) from drinking water included an investigation of the possibility of reusing the resins after an in situ regeneration step.

Water Treatment Plant Final Report Plainfield GAC Pilot Project, GAC2018
Prein & Newhof on behalf of the Plainfield Charter Township, 80 pp, 2019

PFAS were detected in raw water from the Versluis Well Field, which supplies drinking water to the Plainfield Charter Township during peak water demands in summer months. The combined concentrations of PFOA and PFOS ranged from 4.9-10.3 ng/L. Plainfield's water treatment process was not designed to remove PFAS compounds. A pilot study was conducted to determine how effective retrofitting the existing dual media filters in the existing treatment plant with granular activated carbon (GAC) was to maintain existing water treatment standards and remove PFAS. The pilot tested three GAC filter setups: sand+Calgon F-820 and an 8.2 min empty bed contact time (EBCT), Calgon F-800 and an 8.1 min EBCT, and Calgon F-400 and a 10.1 EBCT. While the plant saw some breakthrough of PFAS compounds, the F-400 was the GAC of choice for total organic carbon and PFAS removal. On a short-term basis, it was feasible and effective for Plainfield Charter Township to address its PFAS contamination by retrofitting its existing rapid sand filters. Additional information: 2019-2020 water quality reports

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Bioremediation

Aerobic Biotransformation of Fluorotelomer Thioamido Sulfonate (Lodyne™) in AFFF- Amended Microcosms
Harding-Marjanovic, K., E. Houtz, S. Yi, J. Field, D. Sedlak, and L. Alvarez-Cohen. Environmental Science & Technology 49:7666-7674(2015) [Abstract]

This article describes the aerobic biotransformation of fluorotelomer thioamido sulfonate into other PFASs, including perfluorocarboxylic acids.

Bioaugmentation with Vaults: Novel In Situ Remediation Strategy for Transformation of Perfluoroalkyl Compounds
Mahendra, S., L.H. Rome, V.A. Kickhoefer, and M. Wang.
SERDP Project ER-2422, 58 pp, 2016

Researchers pursued a single-step method for encapsulating active enzymes (e.g., laccase enzymes from wood-rotting fungi) in naturally synthesized, hollow ribonucleoprotein particles, referred to as recombinant vaults, to address PFOA in groundwater.

Effects of Aqueous Film-Forming Foams (AFFFs) on Trichloroethene (TCE) Dechlorination by a Dehalococcoides mccartyi-Containing Microbial Community
Harding-Marjanovic, K.C., S. Yi, T.S. Weathers, J.O. Sharp, D.L. Sedlak, and L. Alvarez-Cohen.
Environmental Science & Technology 50(7):3352-3361(2016) [Abstract]

Researchers investigated the effects of AFFF components on TCE biodegradation potential.

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Chemical Oxidation

Activated Persulfate Oxidation of Perfluorooctanoic Acid (PFOA) in Groundwater under Acidic Conditions
Yin, P., Z. Hu, X. Song, J. Liu, and N. Lin.
International Journal of Environmental Research and Public Health 13(6):602(2016)

PFOA degradation using activated persulfate was examined under varied experimental conditions to evaluate the impact of different factors on persulfate activity, including pH, temperature, persulfate dosage, and reaction time.

Applications of ScisoR® for In-situ Treatment of PFOS in Soil and Groundwater
Horneman, A.
Emerging Contaminants Summit, March 1-2, 2016, Westminster, Colorado. Poster abstract, 2016

This presentation describes testing of ScisoR® (i.e., Smart combined in situ oxidation and Reduction) technology at bench scale to provide proof of concept and site-specific design parameters for pilot- and full-scale application of the technology for PFOS. Additional information: U.S. Patent Application

Chemical Oxidation of Per- and Polyfluoroalkyl Substances in AFFF-Impacted Groundwater
Bruton, T.
Emerging Contaminants Summit, March 1-2, 2016, Westminster, Colorado. (Abstract only)

The effect of either Fenton's reagent or persulfate on the fate of PFAS chemicals in AFFF was studied in bench-scale experiments.

Chemical Oxidation of Poly- and Perfluoroalkyl Substances in AFFF-Impacted Groundwater
Bruton, T. and D. Sedlak.
An Integrated Approach to Sustainable Solutions: Session II – Technologies for Water Remediation. A CLU-IN Webinar sponsored by NIEHS, 20 June 2016. 31 slides, 2016

An overview of research performed at UC Berkeley to develop chemical oxidation treatments for in situ remediation of PFAS is available in an archived presentation.

Degradation of Perfluoroalkyl Acids by Enzyme Catalyzed Oxidative Humification Reactions
Luo, Qi, Ph.D. dissertation, University of Georgia, 210 pp, 2015

The ability of an enhanced natural process called enzyme-catalyzed oxidative humification reactions (ECOHRs) is being studied to evaluate its effectiveness in transforming both PFOA and PFOS in the aqueous phase at environmentally relevant conditions. Additionally, PFOA degradation efficiency by ECOHRs in soil was studied without amendment (i.e., unamended natural soil organic matter only) and by addition of extra natural organic matter (i.e., soybean meal).

Degradation of Perfluoroctane Sulfonate by Enzyme Catalyzed Oxidative Humification Reactions
Huang, Q.
Abstracts: American Chemical Society Conference, Philadelphia, August 2016 [Longer abstract]

This presentation discusses the degradation of PFOS by laccase-induced enzyme-catalyzed oxidative humification reactions (ECOHRs) using 1-hydroxybenzotriazole as a mediator to assess the potential of the reactions for removing PFOS from a contaminated environment.

Degrading Non-Volatile Halogenated Organic Compounds
Inventors: T.A. Pancras, W. Plaisier, P. Jacobus, A. Dols, and J.A. Barbier.
Patent Application WO 2013119121 A1, Applicant: Arcadis Nederland B.V.

The invention relates to a method of degrading non-volatile halogenated organic compounds, to use of the method for decontaminating a PFOS- and PFOA-contaminated medium, and in a composition that is suitable for application.

Destruction of PFOS in Groundwater: A New In Situ Remediation Technology for Per/Polyfluorinated Alkyl Substances
Ross, I.
Abstracts: American Chemical Society Conference, 2016 [Longer abstract]

This presentation discusses a demonstration of the ScisoR® technology at an AFFF site in Scandinavia. ScisoR® uses both oxidation and reduction reactions.

Effect of Temperature on Oxidative Transformation of Perfluorooctanoic Acid (PFOA) by Persulfate Activation in Water
Liu, C.S., Higgins, C.P., Wang, F., and K. Shih.
Separation and Purification Technology 91:46-51(2012)

Degradation of aqueous PFOA at different temperatures was examined using heat-activated persulfate.

Efficient Degradation of Perfluorooctanoic Acid (PFOA) by Photocatalytic Ozonation
Huang, J., X. Wang, Z. Pan, X. Li, Y. Ling, and L. Li.
Chemical Engineering Journal 296:329-334(2016) [Abstract]

A study was conducted to evaluate the extent to which PFOA can be efficiently degraded by photocatalysis and ozonation in combination and the composition of the PFOA degradation intermediates.

Electrochemical Degradation of PFAS Mass in Redundant Stocks of AFFF Concentrate and First Flush Washwater - Pilot-Scale Field Demonstration
Santacroce, J., R. Casson, S. Laing, and R. Mora. | Remediation Technologies Symposium East, 1-3 June, Niagara Falls, Ontario, 29 slides, 2022

A three-month field pilot using electrochemical advanced oxidation processes (EAOP) was conducted at a facility in Australia to destroy PFAS mass contained within the solutions generated from foam transition programs. The pilot treated 13,200 L of redundant 'end-of-life' AFFF and 20,800 L of PFAS-impacted first flush wash water. The trial comprised a series of experiments under different treatment conditions and reactor configurations, including different retention times/flow rates and current supply. The experimental flow rate ranged from 200 to 1,530 L/m² per hour. Time-course samples were collected and analyzed for 30 PFAS compounds, total oxidizable precursor assay (TOPA)-PFAS, select anions (fluoride, sulfate, and perchlorate), total organic carbon, SVOCs, and metals. Total organic fluorine (TOF) data was collected for mass balance evaluation. After EO treatment, post-treatment first flush results indicated that PFOA concentrations were reduced from 77%-99%, and the sum of PFOS and PFHxS were reduced from 95%-100%. TOF data indicated that, under ideal operational parameters, 96% of measurable and unmeasurable PFAS mass was reduced. Following EO of post-treatment 'end- of-life' AFFF concentrate, TOF data indicated that the combined measurable and unmeasurable PFAS mass was reduced by 76%. Regulated PFAS were not detected in the AFFF as it was a C6 pure foam. On average, the EO system consumed 4.92 kWh of electricity per day, and the system can be powered by solar energy (supplemented with a battery) for future applications. A field pilot is underway at a second system constructed in the U.S. enhanced with flow-through capability and greater current density.

Heat-Activated Persulfate Oxidation of PFOA, 6:2 Fluorotelomer Sulfonate, and PFOS under Conditions Suitable for In-Situ Groundwater Remediation
Park, S., L. Lee, V. Medina, A. Zull, and S. Waisner.
Chemosphere 145:376-383(2016) [Abstract]

PFOA oxidation by heat-activated persulfate at 20-60°C and in the presence of soluble fuel components was evaluated to assess the feasibility of in situ remediation of groundwater.

Hydroxyl-Radical Based Advanced Oxidation Processes Can Increase Perfluoroalkyl Substances beyond Drinking Water Standards: Results from a Pilot Study
Venkatesan, A.K., C.-S. Lee, and C.J. Gobler.
Science of The Total Environment 847:157577(2022). [Abstract]

The fate of PFASs in seven pilot-scale advanced oxidation processes (AOPs), including UV/H₂O₂, UV/Cl₂, UV/TiO₂, and O₂/H₂O₂ technologies, was assessed at four drinking water systems across New York State. Seven of 18 PFAS were detected in the influent at concentrations ranging from below method detection to 64 ng/L. All detected PFAS showed an increase in concentration after treatment, presumably due to unknown precursor transformation with specific increases for PFBS, PFHxA, PFHpA, PFHxS), PFOA, PFOS, and PFNA averaging 405% (range: 0-1,220%), 1.0% (-7-9%), 3.8% (0-9.5%), 3.3% (-11-13%), 14% (0-48%), 13% (3-25%), and 2% (0-5.2%), respectively. PFAS concentration increases were dependent on UV and oxidant dose, confirming that transformation reactions occurred due to AOPs similar to a total oxidizable precursor assay. At one site, PFOA levels exceeded the current regulatory drinking water standard of 10 ng/L after but not before treatment, highlighting the importance of considering the potential impact of AOP on treated water quality when designing treatment systems for regulatory compliance. The increase in PFAS concentration in the AOP systems positively correlated (r = 0.91) with nitrate levels in groundwater, suggesting that onsite septic discharges may be an important source of PFAS contamination in these unsewered study areas. Results reveal that hydroxyl radical-based AOPs, although ineffective in treating PFAS, can help reveal the extent of PFAS contamination in source waters.

Impact of ISCO Treatment on PFAA Co-Contaminants at a Former Fire Training Area
Eberle, D., R. Ball, and T.B. Boving.
Environmental Science & Technology 51(9):5127-5136(2017) [Abstract]

Soil and groundwater samples were collected before and after an ISCO pilot-scale field test to assess the impact of a peroxone-activated persulfate (OxyZone) technology aimed mainly at remediation of chlorinated VOCs (PCE, 1,1,1-TCA, dichlorobenzenes) and perfluoroalkyl acids.

Innovative Oxidation Pathways for the Treatment of Traditional and Emerging Contaminants
Ahmad, Mushtaque, Ph.D. dissertation, Washington State University, 117 pp, 2012

Chapter 2 examines the degradation of PFOA by reactive species generated through catalyzed hydrogen peroxide propagation reactions. Chapter 3 discusses the potential for glucose as a persulfate activator at pH both acidic (3) and basic (12.5). Chapter 4 examines GAC regeneration potential by two superoxide systems: (a) hydrogen peroxide-bicarbonate and (b) percarbonate.

Innovative Technologies on Treating Perfluoroalkyl Substances
Chiang, D., Q. Luo, D. Woodward, and Q. Huang.
Cleanup Conference 2015, 13-16 September, Melbourne, Australia, WC22, 358-359, 2015

This presentation discusses how the potential and mechanisms of PFAS degradation (with PFOA as the model PFAS) by enzyme-catalyzed oxidative humification reactions was investigated.

Investigation of In-Situ Chemical Oxidation Techniques for AFFF Treatment in Soil-Water Microcosms
Bishop, J., J. Hatton, D. Berggren, J. Field, K. Barzen-Hanson, T. Bruton, and W. DiGuiseppi.
Abstracts: American Chemical Society Conference, 2016 [Longer abstract]

This presentation discussed oxidation of an AFFF sample in soil-water microcosm systems, using low-pH and high-pH catalyzed hydrogen peroxide and alkaline-activated persulfate at varying application doses.

Laccase-Catalyzed Degradation of Perfluorooctanoic Acid
Luo, W., J. Lu, H. Zhang, Z. Wang, M. Feng, S.-Y.D. Chiang, D. Woodward, and Q. Huang.
Environmental Science & Technology Letters 2(7):198-203(2015) [Abstract]

The effects of enzyme-catalyzed oxidative humification reactions on PFOA decomposition in a mineral buffer solution were studied.

Management of AFFF Impacts in Subsurface Environments and Assessment of Novel and Commercially Available PFAS-Free Foams (Part 1)
Cates, E. and J. Payne. SERDP & ESTCP Webinar Series, Webinar #139, September 2021

On September 9, 2021, SERDP and ESTCP sponsored webinars focused on DoD-funded research to manage the impacts of traditional aqueous film-forming foams (AFFF) by destroying PFAS in wastewaters and developing PFAS-free firefighting foams. Specifically, investigators discussed a photocatalytic treatment system to treat PFAS-impacted wastewaters and the physical and chemical processes of PFAS-free firefighting foams that affect performance.

Oxidative Decomposition of Perfluorooctanesulfonate in Water by Permanganate
Liu, C.S., Shih, K., and F. Wang
Separation and Purification Technology 87:95-100(2012)

Batch experiments were conducted to examine the oxidative decomposition of PFOS by permanganate in aqueous solutions with attention to the effects of temperature, initial permanganate concentration, and pH on PFOS decomposition efficiency.

Perfluorooctanoic Acid Degradation in the Presence of Fe(III) Under Natural Sunlight
Liu, D., Z. Xiu, F. Liu, G. Wu, D. Adamson, C. Newell, P. Vikesland, A.-L. Tsai, P.J. Alvarez.
Journal of Hazardous Materials 262:456-463(2013)

Decomposition of PFOA in the presence of sunlight and Fe(III) is discussed.

Technology Review and Evaluation of Different Chemical Oxidation Conditions on Treatability of PFAS
Dombrowski, P.M., P. Kakarla, W. Caldicott, Y. Chin, V. Sadeghi, D. Bogdan, F. Barajas-Rodriguez, and S.-Y.D. Chiang. Remediation Journal 28(2):135-150(2018) [Open Access]

An overview of relevant literature summarizes the use of single or combined reagent chemical oxidation processes that offer insight into oxidation-reduction chemistries potentially capable of PFAS degradation.

Supercritical Water Oxidation as an Innovative Technology for PFAS Destruction
Krause, M.J., E. Thoma. E. Sahle-Damesessie, B. Crone, A. Whitehill, E. Shields, and B. Gullett. Journal of Environmental Engineering 148(2)(2022) [Abstract]

Three supercritical water oxidation (SCWO) technology providers were contracted to test the efficacy of SCWO systems to reduce PFAS concentrations in solutions of dilute AFFF. Results of all three demonstration studies showed a >99% reduction of total PFAS identified in a targeted compound analysis, including PFOS and PFOA. PFOS was reduced from 26.2 mg/L to 240 µg/L (Aquarden), 30.4 mg/L to 0.310 µg/L (Battelle), and 190 mg/L to 8.57 µg/L (374Water). Similarly, PFOA was reduced from 930 to 0.14 µg/L, 883 to 0.102 µg/L, and 3,100 µg/L to ND. The chemical oxygen demand of the dilute AFFF was reduced from 4,750 to 5.17 mg/L after treatment, indicating significant organic compound destruction. In one demonstration, a mass balance of the influent and effluent found that the targeted compounds accounted for only 27% of the generated fluoride, suggesting that more PFAS were destroyed than measured and emphasizing the limitations of targeted analysis alone. As a destructive technology, SCWO may be an alternative to incineration and could be a permanent solution for PFAS-laden wastewater rather than disposal by deep well injection or landfilling. Additional information: Presentation from the 3rd National PFAS Conference

Validation of Supercritical Water Oxidation to Destroy Perfluoroalkyl Acids
McDonough, J.T., J. Kirby, C. Bellona, J.A. Quinnan, N. Welty, J. Follin, and K. Liberty.
Remediation [Published online 22 February 2022 before print]

Supercritical water oxidation was field validated to treat a concentrated waste stream of 12 PFAAs with liquid and gaseous analysis, adhering to EPA Other Test Method 45 for stack emission sampling and EPA Method 537.1, with quality control and quality assurance protocols from the DoD/DoE Quality Systems Manual 5.3. Results suggest > 99.999% destruction and removal efficiency of the 12 PFAAs after two ~120-min continuous flow trials, with an overall defluorination of ~62.6%.

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Chemical Reduction

Abiotic Treatment Technologies for In-Site Remediation of Persistent Perfluoroalkyl Acids
Lee, L.S., S. Park, and J. Zenobio.
NICOLE Workshop, June 26, 2015, Manchester, UK. 37 slides, 2015

The efficiency of different amounts of ZVI was evaluated with and without catalyst and vitamin B12 as a function of temperature and time in aqueous batch systems (slides 17-32).

Complete Defluorination of Perfluorinated Compounds by Hydrated Electrons Generated from 3-Indole-acetic-acid in Organomodified Montmorillonite
Tian, H., J. Gao, H. Li, S.A. Boyd, and C, Gu.
Scientific Reports 6:32949(2016)

An indole derivative, 3-indole-acetic-acid, a mercury lamp (254 nm), and organomodified montmorillonite were combined to investigate the effects of hydrated electrons under mild conditions on PFOA and PFOS adsorption on clay minerals.

Efficient Reductive Decomposition of Perfluorooctanesulfonate in a High Photon Flux UV/Sulfite System
Gu, Y., W. Dong, C. Luo, and T. Liu.
Environmental Science & Technology 50: 10554-10561(2016) [Abstract]

The feasibility of employing a high photon flux UV/sulfite system to enhance PFOS decomposition via hydrated electron-induced reduction techniques was investigated.

Photo-Reductive Defluorination of Perfluorooctanoic Acid in Water
Qu, Y., C.J. Zhang, F. Li, J. Chen, Q. Zhou.
Water Research 44:2939-2947(2010) [Abstract]

The efficiency of different amounts of ZVI was evaluated with and without catalyst and vitamin B12 as a function of temperature and time in aqueous batch systems (slides 17-32).

Reductive Degradation of Perfluorinated Compounds In Water Using Mg-Aminoclay Coated Nanoscale Zero Valent Iron
Arvaniti, O.S., Y. Hwang, H.R. Andersen, A.S. Stasinakis, N.S. Thomaidis, and M. Aloupi.
Chemical Engineering Journal 262:133-139(2015)

The main objectives of this study were to investigate the removal of four PFCs [PFOA, PFOS, perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA)] using MgAC-coated NZVI in comparison with commercial NZVI powder and freshly synthesized uncoated NZVI, with reference to the effects of initial pH, reaction temperature, and NZVI dosage. A comparison of fresh and aged MgAC-coated NZVI for PFOS removal was also examined.

Reductive Defluorination of Perfluorooctane Sulfonate
Ochoa-Herrera, V., R. Sierra-Alvarez, A. Somogyi, N.E. Jacobsen, V.H. Wysocki, and J.A. Field.
Environmental Science & Technology 42:3260-3264(2008) [Abstract]

In an investigation of the susceptibility of technical PFOS and PFOS-branched isomers to chemical reductive dehalogenation, vitamin B₁₂ (260 µM) provided the catalyst and Ti(III)-citrate (36 mM) the bulk reductant in anoxic aqueous solution at 70°C and pH 9. Additional information: Ochoa-Herrera's dissertation, Removal of Perfluorooctane Sulfonate (PFOS) and Related Compounds from Industrial Effluents.

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Electrochemical Oxidation

An Electric Fix for Removing Long-Lasting Chemicals in Groundwater
Blotevogel, J.
The Conversation, 10 Apr 2017

Challenges, innovations, and progress in ongoing research to develop an in situ electrolytic barrier to treat PFAS-contaminated water are discussed.

Electrochemical Oxidation Processes For PFAS Removal From Contaminated Water and Wastewater: Fundamentals, Gaps and Opportunities Towards Practical Implementation
Veciana, M., J. Bräunig, A. Farhat, M.L.Pype, S. Freduia, G.Carvalho, J. Keller, and P. Ledezma. Journal of Hazardous Materials 434:128886(2022)

This review examines the state of the art of electrochemical oxidation (EO) for destruction of PFAS, and comprehensively compares operating parameters and treatment performance indicators for both synthetic and real contaminated water and wastewater media. The evaluation shows the need to use environmentally-relevant media to properly quantify the effectiveness/efficiency of EO for PFAS treatment.

Electrochemical Treatment of Perfluorooctanoic Acid and Perfluorooctane Sulfonate: Insights into Mechanisms and Application to Groundwater Treatment
Schaefer, C.E., C. Andaya, A. Burant, C.W. Condee, A. Urtiaga, T.J. Strathmann, and C.P. Higgins.
Chemical Engineering Journal 317:424-432(2017) [Abstract]

Electrochemical treatment of PFOA and PFOS using a nanocrystalline boron-doped diamond anode was investigated in a series of bench-scale batch experiments focused on assessing the impacts of chloride electrolyte and of hydroxyl radical scavenger TBA on both the rates of PFOA and PFOS removal and the corresponding rates of defluorination.

Field Demonstration of a Pilot-Scale Plasma Reactor for the Rapid Removal of Poly- and Perfluoroalkyl Substances in Groundwater
Nau-Hix, C., N. Multari, R.K. Singh, S. Richardson, P. Kulkarni, R.H. Anderson, T.M. Holsen, and S.M. Thagard. ǀ ACS ES&T Water 1(3):680-687(2021) [Abstract]

A pilot-scale plasma-based water treatment system containing two enhanced contact plasma reactors was deployed at Wright-Patterson Air Force Base to treat PFAS in AFFF-impacted groundwater from two monitoring wells. Extracted water was treated through the plasma trailer in a semi-batch mode at flow rates ranging from 2.4-8.4 L/min. Long-chain PFAAs (fluorocarbon chain of ≥6) and PFAS precursors were reduced by ≥90% for all flow rates in a single cycle through the reactors. Combined PFOA and PFOS concentrations lower than EPA's health advisory level of 70 ng/L were achieved in fewer than three cycles through the reactors. Short-chain PFAAs (fluorocarbon chain of ≤5) were removed to a lesser extent (0-95%) due to their generation during plasma treatment of long-chain PFAAs and PFAS precursors and limited accumulation at the plasma-liquid interface of the reactor. Batch mode experiments were performed by adding cetrimonium bromide to improve the destruction of short-chain PFAAs, resulting in an 88% reduction within 120 min of treatment. More information: Wright-Patterson Air Force Base News Article

Remediation of Per- and Polyfluoroalkyls (PFAS) via Electrochemical Methods
Sharma, S., N.P. Shetti, S. Basu, M.N. Nadagouda, and T.M. Aminabhavi. Chemical Engineering Journal 430(Part 2):132895(2022) [Abstract]

This review explores the latest advances and limitations of electrochemical treatment methods for PFAs. Recent findings emphasize the use of boron-doped diamond anodes and titanium sub-oxide ceramic anodes, specifically Magnéli phase Ti₄O₇ electrode as these can achieve almost ~99% of PFAs removal with the least energy requirement compared to other existing anodes. The influence of design parameters and electrode materials are considered and the mechanisms of electro-oxidation of PFAs onto anodic surface degradation, besides the various side-products formed after the process are analyzed.

Excavation and Off-Site Disposal

Minnesota Decision Document, 3M Oakdale Disposal Site, City of Oakdale, Washington County, Minnesota
Minnesota Pollution Control Agency (MPCA), 12 pp, 2008

The Oakdale Dump Site was placed on EPA's Superfund list in the early 1980s due to soil and groundwater contamination from VOCs. A large volume of waste material and contaminated soil was removed and replaced with clean soil between 1984 and 1985. In 2004, 3M disclosed that industrial wastes containing perfluorinated chemicals were disposed of at the Oakdale Disposal Site. In 2008, the State of Minnesota selected excavation of soil with disposal at an off-site landfill to address the PFAS contamination.

Minnesota Decision Document, 3M Woodbury Disposal Site, City of Woodbury, Washington County, Minnesota
Minnesota Pollution Control Agency (MPCA), 11 pp, 2008

3M disclosed in 2005 that perfluorinated chemicals had been disposed of at the Woodbury Disposal Site from 1960 until 1966. In 2008, the State of Minnesota selected excavation of soil with disposal at an off-site landfill to address the PFAS contamination.

Minnesota Decision Document, 3M Cottage Grove Disposal Site, City of Cottage Grove, Washington County, Minnesota
Minnesota Pollution Control Agency (MPCA), 10 pp, 2009

The Cottage Grove Site was placed on the State of Minnesota Superfund list in 1984 due to soil and groundwater contaminated with VOCs. In 2009, the State of Minnesota selected excavation of sediment and soil with disposal at an off-site landfill to address the PFAS contamination.

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Incineration and Thermal Treatment

Bench-Scale VEG Research & Development Study: Implementation Memorandum for Ex-Situ Thermal Desorption of Perfluoroalkyl Compounds (PFCs) in Soils
Javaherian, M.
Technical Memorandum, 26 Feb 2016

Summary of bench-scale research completed to thermally treat PFCs in soils using Vapor Energy Generator (VEG) technology.

Emissions of Fluorinated Compounds from the Combustion of Carpeting
Lemieux, P., M. Strynar, D. Tabor, J. Wood, M. Cooke, B. Rayfield, and P. Kariher.
2007 International Conference on Incineration and Thermal Treatment Technologies, 14-18 May, Phoenix, AZ. Air & Waste Management Association, 2007 [Abstract]

Some of the stain-resistant coatings that carpeting is treated with contain perfluorinated compounds such as PFOA and their corresponding homologues (C_6-C₁₄ acids) as well as fluorotelomer alcohols and fluoropolymers. This paper reports on a study of combustion of carpeting in a 0.73 kW pilot-scale rotary kiln incinerator simulator to assess the potential for emissions of fluorinated compounds from combustion devices.

Effectiveness and Mechanisms of Defluorination of Perfluorinated Alkyl Substances by Calcium Compounds during Waste Thermal Treatment
Wang, F., X. Lu, X.Y. Li, and K. Shih.
Environmental Science & Technology 49(9):5672-5680(2015) [Abstract]

The mineralization of PFASs by different calcium compounds during waste thermal treatment (>400°C) was systemically studied to evaluate the different mineralization effects and determine the most effective Ca reagent for PFAS defluorination.

Final Report: Laboratory-Scale Thermal Degradation of Perfluoro-Octanyl Sulfonate and Related Substances
3M Company. UDR-TR-03-00044, 142 pp, 2003

A lab-scale incineration study of PFOS and C8 perfluorosulfonamides was conducted to determine if a properly operating full-scale (high temperature) incineration system can adequately dispose of those perfluorinated substances. The goal was to determine whether incineration of the substances is likely to be a significant source of PFOS into the environment. Additional information: Summary paper

Gas-Phase NMR Studies of the Thermolysis of Perfluorooctanoic Acid
Krusic, P.J., A.A. Marchione, and D.C. Roe.
Journal of Fluorine Chemistry 126(11-12):1510-1516(2005) [Abstract]

The thermolysis of PFOA was studied kinetically by high-temperature (<400°C) gas-phase nuclear magnetic resonance (NMR) in both sodium borosilicate glass and quartz ampoules to evaluate the different rates at which PFOA thermolysis proceeds, depending on concentration and on the physical and chemical environment. Results were compared to the pyrolysis of ammonium perfluorooctanoate.

Influence of Calcium Hydroxide on the Fate of Perfluorooctanesulfonate under Thermal Conditions
Wang, F., X. Lu, K. Shih, and C. Liu.
Journal of Hazardous Materials 192(3):1067-1071(2011) [Abstract]

PFOS, commonly dominant in wastewater sludge, was mixed with hydrated lime to quantitatively observe their interaction under different temperatures (350-600°C).

Investigation of Waste Incineration of Fluorotelomer-Based Polymers as a Potential Source of PFOA in the Environment
Taylor, P.H., T. Yamada, R.C. Striebich, J.L. Graham, and R.J. Giraud.
Chemosphere 110:17-22(2014) [Abstract]

Waste incineration of fluorotelomer-based polymers under conditions representative of typical municipal waste combustor and medical waste incinerator operations in the U.S. was investigated to assess the potential for the formation of detectable levels of PFOA.

Mineralization Behavior of Fluorine in Perfluorooctanesulfonate (PFOS) During Thermal Treatment of Lime-Conditioned Sludge
Wang, F., K. Shih, X. Lu, and C. Liu.
Environmental Science & Technology 47(6):2621-2627(2013) [Abstract]

Researchers studied the variations in the fate and transport of fluorine in PFOS when the sludge was subject to different PFOS contents and treatment types, such as heat drying or incineration.

Pilot-Scale Thermal Treatment of PFAS-Laden Materials
Potter, P., B. Crone, and M. Mills. ACS Spring 2024 National Meeting, New Orleans, LA, 17-20 March, 22 slides, 2024.

Results from a pilot-scale system used to perform both biosolid incineration and GAC regeneration will be presented along with a summary of current EPA research in this field.

Residual Organic Fluorinated Compounds from Thermal Treatment of PFOA, PFHxA and PFOS Adsorbed onto Granular Activated Carbon (GAC)
Watanabe, N., S. Takemine, K. Yamamoto, Y. Haga, and M. Takata.
Journal of Material Cycles and Waste Management 18(4):625-630(2016) [Abstract]

PFOA, PFHxA, and PFOS adsorbed onto GAC were thermally treated in a N₂ gas stream to assess the fate of PFASs during thermal regeneration of GAC used for water treatment.

Summary of the Guideline on the Treatment of Wastes Containing Perfluorooctane Sulfonic Acid (PFOS), and Its Salts in Japan
Ministry of the Environment of Japan, 14 pp, 2013

Research to support the appropriate handling and incineration of PFOS-containing solids and liquids in Japan is summarized.

Thermal Degradation of Fluorotelomer Treated Articles and Related Materials
Yamada, T., P.H. Taylor, R.C. Buck, M.A. Kaiser, and R.J. Giraud.
Chemosphere 61(7):974-984(2005) [Abstract]

The thermal degradation of a polyester/cellulose fabric substrate treated with a fluorotelomer-based acrylic polymer was tested under lab conditions representing combustion conditions typical of a municipal incinerator with an average temperature of 1000°C or greater over ~2s residence time.

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Membrane Filtration (Reverse Osmosis and Nanofiltration)

Biological Wastewater Treatment Followed by Physicochemical Treatment for the Removal of Fluorinated Surfactants
Schroeder, H.F., H.J. Jose, W. Gebhardt, R.F.P.M. Moreira, and J. Pinnekamp.
Water Science & Technology 61(12):3208-3215(2010) [Abstract]

Microfiltration membranes in a membrane bioreactor were applied to municipal wastewater spiked with PFOA and PFOS, and the permeates were treated using ozone or different advanced oxidation techniques.

Effect of Flux (Transmembrane Pressure) and Membrane Properties on Fouling and Rejection of Reverse Osmosis and Nanofiltration Membranes Treating Perfluorooctane Sulfonate Containing Wastewater
Tang, C.Y., Q.S. Fu, C.S. Criddle, and J.O. Leckie.
Environmental Science & Technology 41(6):2008-2014(2007) [Abstract]

Five RO membranes and three NF membranes were tested at a feed concentration of 10 ppm PFOS in wastewater over 4 days in a systematic investigation of the PFOS rejection and permeate flux performances.

Evaluation of the Removal Efficiency of Per- and Polyfluoroalkyl Substances in Drinking Water Using Nanofiltration Membranes, Active Carbon and Anion Exchange
Lindegren, Klara, Master's thesis, Swedish University of Agricultural Sciences, 66 pp, 2015

The efficiency of nanofiltration membranes, active carbon, and anion exchange was investigated at a drinking water treatment plant in Uppsala, Sweden, using a nanofiltration pilot with two 270NF membranes (Dow Filmtech™) connected in series and results from a GAC (Filtrasorb 400®) and anion exchange (Purolite® A-600) column experiment.

Fabrication of Novel Poly(m-Phenylene Isophthalamide) Hollow Fiber Nanofiltration Membrane for Effective Removal of Trace Amount Perfluorooctane Sulfonate from Water
Wang, T., C. Zhao, P. Li, Y. Li, and J. Wang.
Journal of Membrane Science 477:74-85(2015) [Abstract]

A hollow fiber nanofiltration membrane was fabricated from poly(m-phenylene isophthalamide) (PMIA) using a dry-jet wet spinning technology for sustainable water recovery from water containing trace amounts of PFOS. PFOS rejection experiments were carried out at trans-membrane pressures ranging from 4x10⁵ Pa to 1.0x10⁶ Pa and PFOS concentrations from 50-500 µg/L.

Leachate Treatment Pilot Study at Kandiyohi County Landfill
Oskoui, K. and L. Kleindl.
RAM/SWANA Conference 2014, 64 slides, 2014 [Longer abstract]

A 2-week pilot test and an engineering study of the LeachBuster™ single-pass membrane system was conducted to demonstrate how the system would work in solving Kandiyohi County's (Minnesota) landfill leachate issues. Inert leachate waste product concentrate was returned to the landfill, and treated effluent was discharged to a sedimentation basin for infiltration to groundwater. Testing for perfluorochemicals was done at ppt concentrations [slides 29-31].

Nanofiltration and Granular Activated Carbon Treatment of Perfluoroalkyl Acids
Appleman, T.D., E.R.V. Dickenson, C. Bellona, and C.P. Higgins.
Journal of Hazardous Materials 260:740-746(2013) [Abstract]

The efficacy of NF and GAC adsorption in removing a suite of PFAAs from water was investigated using virgin flat-sheet NF membranes (NF270, Dow/Filmtec) and small-scale columns packed with Calgon Filtrasorb®300 (F300) carbon. Additional information: Appleman's 2012 thesis

Nanofiltration for Trace Organic Contaminant Removal: Structure, Solution, and Membrane Fouling Effects on the Rejection of Perfluorochemicals
Steinle-Darling, E. and M. Reinhard.
Environmental Science & Technology 42(14):5292-5297(2008) [Abstract]

Rejections of 15 PFCs—5 perfluorinated sulfonates, 9 perfluorinated carboxylates, and perfluorooctane sulfonamide (FOSA)—by four nanofiltration membranes (NF270, NF200, DK, and DL) were measured at increasing and decreasing pH. Accumulation of PFCs on membranes was measured after the completion of rejection experiments.

Perfluorooctane Sulfonate Removal by Nanofiltration Membrane: The Effect and Interaction of Magnesium Ion/Humic Acid
Zhao, C., C.Y. Tang, P. Li, P. Adrian, and G. Hu.
Journal of Membrane Science 503:31-41(2016) [Abstract]

A novel nanofiltration membrane (NF270) was investigated for the interaction and effect of Mg²⁺ ion and humic acid in the feed solution on PFOS removal efficiency and total permeate flux.

Perfluorooctane Sulfonate Removal by Nanofiltration Membrane: The Role of Calcium Ions
Zhao, C., J. Zhang, G. He, T. Wang, D. Hou, and Z. Luan.
Chemical Engineering Journal 233:224-232(2013) [Abstract]

The NF270 membrane was used to remove PFOS from simulated surface water containing calcium ions in an investigation of the effects of PFOS concentration, calcium concentration, and pH on PFOS rejection.

Removal of Perfluorooctane Sulfonate by a Gravity-Driven Membrane: Filtration Performance and Regeneration Behavior
Guo, H., J. Wang, Y. Han, Y. Feng, K. Shih, and C.Y. Tang.
Separation and Purification Technology 174:136-144(2017) [Abstract]

Gravity-driven filtration using a highly porous nanofibrous membrane (water permeability of 354.9 LMH/kPa) was systematically investigated for PFOS removal under a wide range of water chemistry conditions, followed by an assessment of methanol rinsing as a membrane regeneration process.

Removal of Perfluorooctane Sulfonates from Water by a Hybrid Coagulation-Nanofiltration Process
Yu, Y., C. Zhao, L. Yu, P. Li, T. Wang, and Y Xu.
Chemical Engineering Journal 289:7-16(2016) [Abstract]

In an investigation of the effect of coagulation pretreatment on the removal efficiency of PFOS by nanofiltration, NF270 and HYDRACORE membranes were used to test the PFOS rejections in three different solutions: deionized water, humic acid solution, and coagulation solution. Accumulation on the membranes was characterized.

Removal of Perfluorooctanoic Acid (PFOA) in Groundwater by Nanofiltration Membrane
Boonya-atichart, A., S.K. Boontanon, and N. Boontanon.
Water Science and Technology 74(10):(2016) [Abstract]

The removal efficiency of a nanofiltration membrane for PFOA in spiked deionized water and spiked groundwater samples was analyzed by HPLC-MS/MS.

Removal of PFOA by Hybrid Membrane Filtration Using PAC and Hydrotalcite
Rattanaoudom, R. and C. Visvanathan.
Desalination and Water Treatment 32:262-270(2011) [Abstract]

An adsorption-based hybrid membrane technology to remove high PFOA concentration from industrial sources compared results from a combination of hydrotalcite-nanofiltration to direct membrane filtration.

Removal of PFOS, PFOA and Other Perfluoroalkyl Acids at Water Reclamation Plants in South East Queensland Australia
Thompson, J., G. Eaglesham, J. Reungoat, Y. Poussade, M. Bartkowf, M. Lawrence, and J.F. Mueller.
Chemosphere 82:9-17(2011) [Abstract]

At two water reclamation plants in Australia, the first plant utilized adsorption and filtration methods alongside ozonation, while the second used membrane processes and advanced oxidation to produce purified recycled water. Researchers tested for the presence of perfluoroalkyl acids after each treatment procedure.

Use of Reverse Osmosis Membranes to Remove Perfluorooctane Sulfonate (PFOS) from Semiconductor Wastewater
Tang, C.Y.Y., Q.S. Fu, A.P. Robertson, C.S. Criddle, and J.O. Leckie.
Environmental Science & Technology 40(23):7343-7349(2006) [Abstract]

In an investigation of the feasibility of using RO membranes for treating semiconductor wastewater containing PFOS, commercial RO membranes were characterized in terms of permeability, salt rejection, scanning electron microscopy, transmission electron microscopy, and membrane surface zeta potential (streaming potential measurements). Filtration tests were performed to determine the membrane flux and PFOS rejection.

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Pump and Treat

Evaluation of the Efficiency of Treatment Techniques in Removing Perfluoroalkyl Substances from Water
Lundgren, Sandra, Master's thesis, Uppsala University, 66 pp, 2014

PFAS removal efficiency was investigated using six different water types with varying concentrations of dissolved organic carbon. Treatment techniques evaluated included anion exchange using MIEX(r) resins, coagulation with iron (III) chloride, adsorption using powdered activated carbon, and nanofiltration membrane.

PFOS Mobility and Remediation in the Vadose and Groundwater Zone of Glaciofluvial Sediments, Gardermoen, Norway
Tuttle, K.J., B. Wejden, A. Fevang, and J. Skjefstad.
NORDROCS 2012: 4th Nordic Joint Meeting on Remediation of Contaminated Sites, International Conference, September 18-21, 2012, Oslo, Norway. 4 pp paper and 13 slides, 2012

When ~40 kg of PFOS in fire suppressants was accidentally released into an infiltration gallery for surface-water runoff at the Oslo International Airport in 2010, the remediation approach was to treat the groundwater to 300 ng/L PFOS via an activated carbon filter before re-infiltrating the treated water to flush the remaining PFOS from the soil. The re-infiltration design was modeled to limit the lateral migration of PFOS during infiltration and determine lateral re-infiltration sites and rates. Slides; Paper

Remediation of Perfluorinated Alkyl Chemicals at a Former Fire-Fighting Training Area
Paterson, L., T. Siemens-Kennedy, and D. Sweeney.
RemTech 2008: Remediation Technologies Symposium, Paper 34, 6 pp, 2008

This paper presents a summary of the chemical characterization of PFASs, development of risk-based criteria for PFASs at the site, and remediation efforts to date associated with PFAS and hydrocarbon removal.

Minnesota Decision Document, 3M Oakdale Disposal Site, City of Oakdale, Washington County, Minnesota
Minnesota Pollution Control Agency (MPCA), 12 pp, 2008

The Oakdale Dump Site was placed on EPA's Superfund list in the early 1980s due to soil and groundwater contamination from VOCs. A pump-out system was installed in 1984-1985 to control VOCs migration. In 2004, 3M disclosed that industrial wastes containing perfluorinated chemicals were disposed of at the Oakdale Disposal Site. The State of Minnesota selected enhanced groundwater recovery to expand and improve the existing groundwater pump-out system to prevent the migration of PFAS contamination. The extracted groundwater will be treated by an air stripper to remove VOCs followed by GAC prior to discharge to sanitary sewer.

Minnesota Decision Document, 3M Woodbury Disposal Site, City of Woodbury, Washington County, Minnesota
Minnesota Pollution Control Agency (MPCA), 11 pp, 2008

3M disclosed in 2005 that perfluorinated chemicals had been disposed at the Woodbury Disposal Site from 1960 until 1966. In 2008, the State of Minnesota determined that the existing groundwater pump-out system was an effective barrier to the migration of perfluorinated contaminants.

Minnesota Decision Document, 3M Cottage Grove Disposal Site, City of Cottage Grove, Washington County, Minnesota
Minnesota Pollution Control Agency (MPCA), 10 pp, 2009

The Cottage Grove Site was placed on the State of Minnesota Superfund list in 1984 due to soil and groundwater contaminated with VOCs. A groundwater pump-out system was installed to prevent VOC-contaminated ground water from reaching the Mississippi River. The State of Minnesota selected enhanced groundwater recovery to expand and improve the existing groundwater pump-out system to prevent the migration of PFAS contamination. The extracted groundwater will be treated by an on-site wastewater treatment plant equipped with a GAC finishing system prior to discharge to the Mississippi River.

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Solidification/Stabilization

Evaluation of a Solidification/Stabilization Process for PFAS Contaminated Soils
Barth, E., J. McKernan, D. Bless, D. Cutt, S. Hartzell, and K. Dasu.
The Remplex Virtual Global Summit, 8-12 November, virtual, 25 slides, 2021

Granular activated carbon (GAC), an activated carbon-clay blend, modified clay, biochar, and an Fe-amended biochar were evaluated in a bench-scale study as potential sorbents for in situ stabilization/solidification of PFAS-contaminated soil. Cement was added as a binding agent to achieve physical solidification. Results indicated that GAC was slightly more effective than the other sorbents for a 3,000 µg/L solution containing a mixture of six PFAS analytes (500 µg/L concentration each of shorter- and longer-chain alkyl acids), and was the only sorbent further evaluated in the study. Immobilization effectiveness was evaluated on samples obtained from two sites using EPA Method 1312, Synthetic Precipitation Leaching Procedure. Adding GAC sorbent substantially reduced PFAS leachability from contaminated soil samples for most PFAS. Adding cement as a physical binding agent further decreased leachability for many PFAS compounds. Immobilization of PFAS detected in the leachate from two samples ranged from 87.1% to 99.9%. The lab results may apply to pilot or field-scale studies within a broader suite of PFAS contaminated site treatment options currently available to address contaminated soil.

Field-Scale Demonstration of PFAS Leachability Following In Situ Soil Stabilization
McDonough, J.T., R.H. Anderson, J.R. Lang, D. Liles, K. Matteson, and T. Olechiw.
ACS Omega 7(1):419-429(2022)

A field-scale validation compared the efficacy of commercially available stabilization amendments to mitigate PFAS leaching from aqueous film-forming foam (AFFF)-impacted source zones. The work included bench-scale testing to evaluate multiple amendments and application concentrations to mitigate PFAS leachability, followed by field-scale soil mixing. FLUORO-SORB Adsorbent (FS) and RemBind (RB) were selected for field-scale evaluation. Five ~28 m3 test pits (~3m x 3m x 3m) were mixed using conventional construction equipment. One control test pit (Test Pit 1) included Portland cement (PC) only (5% dw). The other four test pits (Test Pits 2 through 5) compared 5 and 10% ratios (dw) of FS and RB (with PC). Five separate monitoring events included two to three sample cores collected from each test pit for EPA Method 1315 leaching analysis. After 1 year, a mass balance for each test pit compared the total PFAS soil mass before, during, and after leach testing. Bench-scale and field-scale data demonstrated a >99% decrease in total PFAS leachability (mass basis; >98% mole basis), confirmed by total oxidizable precursor assay results.

Immobilization of PFASs Using Activated Carbon and Aluminum Hydroxide
Birk, G.M.
Emerging Contaminants Summit, March 1-2, 2016, Westminster, Colorado. 36 slides, 2016

This presentation reports on the results of the use of RemBind™ and RemBind Plus™ on soils contaminated with PFASs at two airport fire training grounds in Australia. The presentation also introduces PerfluorAd, a cationized cellulose-based raw material that is designed to bond with and precipitate PFASs in aqueous media. Additional information: Longer abstract; Rembind poster; PerfluorAd poster

Laboratory-Scale and Pilot-Scale Stabilization and Solidification (S/S) Remediation of Soil Contaminated with Per- and Polyfluoroalkyl Substances (PFASs)
Sorengard, M., P. Gago-Ferrero, D.B. Kleja, and L. Ahrens.
Journal of Hazardous Materials 402:123453(2021)

S/S was evaluated at pilot-scale to treat 6 tons of soil contaminated with PFAS-containing aqueous film-forming foam. The study compared long-term PFAS removal over six years of precipitation in leachate from non-treated contaminated reference soil and S/S-treated soil with 15% binder and 0.2% granular activated carbon. PFAS removal rate from leachate was >97 % for PFHxA, PFOA, PFHxS, and PFOS, but 3% for PFPeA.

Remediation of Perfluorooctane Sulfonate in Contaminated Soils by Modified Clay Adsorbent: A Risk-Based Approach
Das, P., V.A. Arias e., V. Kambala, M. Mallavarupu, and R. Naidu.
Water, Air, & Soil Pollution 224:1714(2013) [Abstract]

Researchers investigated the removal of PFOS from impacted waters and fixation of PFOS in impacted soils using a novel modified clay adsorbent. Treatability studies were performed by treating the PFOS-contaminated soils with MatCARE™ (10% w/w) and then incubating at 25 and 37°C temperatures for a period of one year.

Stabilisation of PFAS in Soils: Long-Term Effectiveness of Carbon-Based Soil Amendments
Navarro, D.A., S. Kabiri, J. Ho, K.C. Bowles, G. Davis, M.J. McLaughlin, and R.S. Kookana.
Environmental Pollution 323:121249(2023)

This article presents results on the effectiveness of select carbon-based sorbents to stabilize PFAS in soil over 4 years under multiple lab leaching conditions. Standard batch leaching tests simulating aggressive, worst-case scenario conditions for leaching (i.e., shaking for 24-48 h at high liquid/solid ratios) were employed to test longevity and durability of stabilization in clay-loam and sandy-loam soil contaminated with PFAS (2 and 14 mg/kg Σ28 PFAS). The different sorbents were applied at 1-6% (w/w), reduced PFAS leaching from the soil to varying degrees. Among the 5 sorbents tested, initial assessments completed 1 week after treatment revealed that 2 powdered activated carbon (PAC) sorbents and 1 biochar could reduce PFAS leaching in the soil by > 95%. Four years after treatment, PAC sorbent performance did not significantly change, while colloidal AC improved and reduced PFAS leaching by at least 94%. The AC-treated soil also appeared to be durable, achieving ≥95% reduction in PFAS leaching under repetitive leaching events (5 times extraction) and with minimal effect of pH (pH 4-10.5). In contrast, the biochars were affected by aging and were at least 22% less effective in reducing PFAS leaching across a range of leaching conditions. Sorbent performance was generally consistent with the sorbent's physical and chemical characteristics. Overall, the AC sorbents used in this study appeared to perform better than the biochars in stabilizing PFAS long-term.

Stabilization of PFAS-Contaminated Soil with Sewage Sludge- and Wood-Based Biochar Sorbents
Sormo, E., C.B.M. Lade, J. Zhang, A.G. Asimakopoulos, G. Wold Asli, M. Hubert, A.I. Goranov, H.P.H. Arp, and G. Cornelissen.
Science of The Total Environment 922:170971(2024)

A study investigated the effects of waste-based biochars on PFAS leaching from sandy soil at a former fire-fighting facility with a low total organic carbon content (TOC, 0.57 ± 0.04%) impacted by PFAS from AFFF. Six different biochars (pyrolyzed at 700-900°C) made from clean wood chips (CWC), waste timber (WT), activated waste timber (aWT), two digested sewage sludges (DSS-1 and DSS-2), and de-watered raw sewage sludge (DWSS) were tested. Up-flow column percolation tests (15 days and 16 pore volume replacements) with 1% biochar indicated that PFOS was retained best by the aWT biochar (99.9% reduction) in the leachate, followed by sludge-based DWSS (98.9%) and DSS-2 (97.8%) and DSS-1 (91.6%). The non-activated wood-based biochars (CWC and WT) reduced leaching by < 42.4 %. Extrapolating this to field conditions, 90% leaching of PFOS would occur after 15 y for unamended soil, and after 1200 y and 12,000 y, respectively, for soil amended with 1% DWSS-amended and aWT biochar. The high effectiveness of aWT and the three sludge-based biochars in reducing PFAS leaching from the soil was attributed largely to high porosity in a pore size range (>1.5 nm) that can accommodate the large PFAS molecules (>1.02-2.20 nm) combined with a high affinity to the biochar matrix. Other factors, like anionic exchange capacity, could play a contributing role. Sorbent effectiveness was better for long-chain than short-chain PFAS due to weaker apolar interactions between the biochar and the latter's shorter hydrophobic CF2-tails.

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Sonochemistry

Effect of Sound Frequency and Initial Concentration on the Sonochemical Degradation of Perfluorooctane Sulfonate (PFOS)
Rodriguez-Freire, L., R. Balachandran, R. Sierra-Alvarez, and M. Keswani.
Journal of Hazardous Materials 300:662-669(2015) [Abstract]

Different levels of PFOS concentration and sound frequency were tested to evaluate their effects on the sonochemical degradation of PFOS.

Enhancing Decomposition Rate of Perfluorooctanoic Acid by Carbonate Radical Assisted Sonochemical Treatment
Thi, L.-A.P., H.-T. Do, and S.-L. Lo.
Ultrasonics Sonochemistry 21(5):1875-1880(2014) [Abstract]

PFOA decomposition by sonochemical treatment was investigated to determine the effects of sodium bicarbonate concentrations, N2 saturation, and pH on decomposition rates and defluorination efficiencies.

Field Demonstration of a Sonolysis Reactor for Treatment of PFAS-Contaminated Groundwater
Kulkarni, P.R., S.D. Richardson, B.N. Nzeribe, D.T. Adamson, S.S. Kalra, S. Mahendra, J. Blotevogel, A. Hanson, G. Dooley, S. Maraviov, and J. Popovic.
Journal of Environmental Engineering 148(11)(2022)

A mobile treatment system equipped with a custom-built sonolysis reactor was deployed at a site in California to treat PFAS-impacted groundwater. Extracted groundwater was treated in a 700-kHz sonolysis reactor for batch treatment under different power densities (122, 203, and 305 W/L) and operating temperatures (15°C and 25°C). Sonolytic treatment resulted in 93%-100% removal of the 15 PFAS, and PFAS degradation rates increased proportionally with increasing power density and temperature at operating conditions of 25°C. Greater removal was observed for PFCAs (95.1% to 100% for PFHxA) than PFSAs (68.3% to 95.2% for PFHxS) for similar carbon chain lengths. Similarly, higher removal was observed for longer-chain PFAS (95.4% to 99.5% for PFOA) compared with short-chain PFAS (56.9% to 90.4% for PFBA). Substantial removal of total oxidizable precursors and specific precursors (65.5% to 99.1% for 4:2 fluorotelomer sulfonate [FTS], 6:2 FTS, 8:2 FTS, and FOSA) was also observed under all conditions tested. Additionally, nitrate formation was observed, with concentrations below MCLs. Results demonstrate that sonolysis treatment of PFAS-contaminated groundwater can effectively degrade PFAS without forming short-chain PFAS and the oxidation byproducts chlorate and perchlorate.

Sonochemical Degradation of Perfluorooctane Sulfonate (PFOS) and Perfluorooctanoate (PFOA) in Landfill Groundwater: Environmental Matrix Effects
Cheng, J., C.D. Vecitis, H. Park, B.T. Mader, and M.R. Hoffmann.
Environmental Science & Technology 42(21):8057-8063(2008) [Abstract]

Scientists evaluated (1) the effect of various organic compounds on the sonochemical decomposition rates of PFOS and PFOA; (2) whether VOCs and dissolved natural organic matter have similar or different effects on sonochemical rate reduction for PFOS and PFOA; and (3) the effects of a combined process of ozonation and sonolysis on the rate loss for PFOS and PFOA in landfill groundwater.

Sonochemical Degradation of Perfluorooctane Sulfonate (PFOS) and Perfluorooctanoate (PFOA) in Groundwater: Kinetic Effects of Matrix Inorganics
Cheng, J., Vecitis, C.D., Park, H., Mader, B.T., and M.R. Hoffmann.
Environmental Science & Technology 44(1):445-450(2010) [Abstract]

Researchers investigated the negative kinetic effects on PFOA and PFOS sonochemical degradation rates of organic constituents in groundwater taken from beneath a landfill, as well as the effect of pH adjustment prior to sonolysis.

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Other

Commercial-Scale Remediation of Per- And Polyfluoroalkyl Substances from a Landfill Leachate Catchment Using Surface-Active Foam Fractionation (SAFF®)
Burns, D.J., H.M. Hinrichsen, P. Stevenson, and P.J.C. Murphy.
Remediation 32(3):139-150(2022) [Abstract]

A commercial-scale field trial using Surface-Active Foam Fractionation (SAFF) was conducted to remove PFAS from a landfill leachate catchment at the Telge Recycling plant in Sweden. PFAS influent and effluent concentrations were sampled 23 times over 10 months, during which ~80,000 m3 of leachate feed was successfully treated without complex pretreatment. The throughput varied between 200 m³ and 500 m³ per day, depending upon the inventory of the upstream leachate catchment. SAFF successfully removed ≥98.7% PFOS, ≥99.7% PFOA, and ≥98.8% PFHxS from the feed stream, including partial/significant removal of other PFAS species, without using absorbent media or chemical amendment consumables. The removal percentages were constrained by the limit of reporting of analytical testing of the treated stream; the actual removal percentages could be higher as detailed by a single sampling event. The mean concentrations of the treated stream were ≤2.34 ng/L PFOS, ≤1.28 ng/L PFOA, and ≤1.00 ng/L PFHxS. The study extends previous analyses to show that removal percentages fall to ~0 at an adsorption coefficient of 0.02 µm with a functional form of a sigmoid on semi-log axes.

A Comprehensive Trial on PFAS Remediation: Hemp Phytoextraction and PFAS Degradation in Harvested Plants
Nason, S.L., S. Thomas, C. Stanley, R. Silliboy, M. Blumenthal, W.L. Zhang, Y.N. Liang, J.P. Jones, N. Zuverza-Mena, J.C. White, C.L. Haynes, V. Vasiliou, M.P. Timko, and B.W. Berger. Environmental Science: Advances 3:304-313(2024)

The Mi'kmaq Nation, Upland Grassroots, and researchers at several institutions participated in a collaborative project that involved phytoremediation field trials using hemp to remove PFAS from soil at the former Loring Air Force Base. PFAS were analyzed in paired hemp and soil samples using targeted and non-targeted analytical approaches. Hydrothermal liquefaction (HTL) was used to degrade PFAS in the harvested hemp tissue. The study identified 28 PFAS in soil and found hemp uptake of 10 of these PFAS. Hemp exhibited greater bioconcentration for carboxylic acids compared to sulfonic acids and shorter-chain compounds compared to longer-chain. In total, ~1.4 mg of PFAS was removed from the soil via uptake into hemp stems and leaves, with a ~2% maximum PFAS removed from soil in the most successful area. Degradation of PFAS by HTL was nearly 100% for carboxylic acids, though some sulfonic acids remained. HTL also decreased precursor PFAS and extractable organic fluorine. While hemp phytoremediation does not currently offer a comprehensive solution for PFAS-contaminated soil, the project effectively reduced PFAS levels at the Loring site and underscores the importance of involving community members in research to remediate their lands. Also see article from iScience on the project.

Electrochemical Treatment of Perfluorooctanoic Acid (PFOA) and Perfluorooctane Sulfonic Acid (PFOS) in Groundwater Impacted by Aqueous Film Forming Foams (AFFFs)
Schaefer, C., C. Anday, A. Urtiag, E. McKenzie, and C. Higgins.
Journal of Hazardous Materials, 295:170-175(2015)

Bench-scale experiments were conducted to evaluate electrochemical treatment for the decomposition of PFOA, PFOS, and other perfluoroalkyl acids.

Field-Scale Treatability Study - Soil Washing of PFAS-Contaminated Soils, Peterson Air Force Base, Colorado
Becker, S. and P. Newman. | Remediation Technologies Symposium East, 1-3 June, Niagara Falls, Ontario, 24 slides, 2022

A field-scale treatability study evaluated the effectiveness of soil washing to remove PFAS from soils derived from aqueous film-forming foam (AFFF) release sites at Peterson Air Force Base. The study also generated site-specific treatment system design and operational parameters to optimize PFAS removal. Initially, ~500 yd³ of contaminated soil excavated from a former AFFF spray test area was homogenized to ensure relatively uniform particle size distribution and PFAS concentrations for processing through the soil washing plant. An Incremental Sampling Methodology established pretreatment concentrations of PFAS as a baseline to assess treatment effectiveness. A mobile lab monitored PFAS concentrations in process water at multiple points within the treatment train and in the various system outputs, including organics, gravels, sands, and fines. Ten batches of soil were treated through a patented water-based, closed-loop treatment process that uses particle size and particle density segregation techniques to 'wash' PFAS from the various soil fractions and capture the mobilized PFAS in an effluent stream that was pretreated using settling and flocculation, followed by PFAS treatment with ECT2's regenerable ion exchange resin. Three batches of sediment were dredged and successfully treated from the base stormwater system, demonstrating the ability of the process to treat finer grain size and high-organic matter materials. The soil washing treatment methodology achieved PFAS removal efficiencies between 93 to >99% for the coarse soil fraction and between 82 and 89% for the fine soil fraction. Soil washing liquids with initial PFOS concentrations of 490 µg/L were effectively treated using regenerable IX media to <70 ng/L. Full-scale application offers the potential, when combined with on-site IX media regeneration and regenerate destruction, for complete PFAS removal, zero waste generation, and beneficial reuse of soils.

PFAS Removal from Groundwaters Using Surface-Active Foam Fractionation
Burns, D.J., P. Stevenson, and P.J.C. Murphy. | Remediation 31(4):19-33(2021) [Abstract]

A field trial conducted at the Oakey Army Aviation Centre in Queensland, Australia, evaluated the effectiveness of the Surface-Active Foam Fractionation (SAFF) process at removing PFAS in groundwater. The SAFF process removed ≥99.5% of PFOS, PFHxS, and PFOA aggregates in PFAS-contaminated groundwater. The field trial also demonstrated the sustainability attributes of SAFF. An anionic exchange (AIX) resin "polisher" installed downstream of SAFF removed all trace detectable PFAS species. By reducing the PFAS loading, the SAFF process extends the lifespan of the AIX resin. The extent of PFAS species removal closely correlated with the adsorption coefficient of the molecules at the gas-liquid interface. When the reported adsorption coefficient was greater than ~1.0 x 10^-6m, nearly all PFAS species, including PFOS, PFHxS, and PFOA, were removed by SAFF. Longer-chain PFAS species that benefit from higher adsorption coefficients were easier to remove than shorter-chain species. More information: SAFF; Site documents for the Oakey site

Photocatalytic Degradation of Perfluorooctanoic Acid
Zhang, P. and Z. Li.
Nanotechnology for Water Treatment and Purification: Lecture Notes in Nanoscale Science and Technology 22:79-110(2014) [Abstract]

An overview is provided of recent advances in the photocatalytic degradation of PFOA by Indium(III) oxide, photocatalytic degradation of PFOA by beta-Gallium(III) oxide nanomaterials, and their potential applications in wastewater treatment. See additional information on the application of beta-Gallium(III) oxide to PFOA in another paper (Zhao et al. 2012).

Remediation of Perfluoroalkyl Contaminated Aquifers Using an In-Situ Two-Layer Barrier: Laboratory Batch and Column Study
Huang, Q.
SERDP Project ER-2127, 32 pp, 2013

The primary project objective was to investigate the feasibility of using a PRB to induce effective enzyme-catalyzed humification reactions for in situ remediation of PFCs in groundwater.

Treatment of Perfluorinated Compounds and Nitroaromatics by Photocatalysis in the Presence of Ultraviolet and Solar Light
Tellez, Mario H., Master's thesis, Air Force Institute of Technology, Wright-Patterson AFB, OH.
AFIT-ENV-14-M-64, 104 pp, 2014

2,4-DNT, PFOA, and PFOS were exposed to TiO₂ and Ag-TiO₂ immobilized on glass slides under sunlight and UV light in atmospheric conditions and neutral pH levels.

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