Part 1: PFAS Phytoextraction Testing on Wetland Soils – Challenges and Possibilities
Rachel Theriault, Golder Associates Ltd.
Golder Associates Limited was mandated to evaluate remediation options for per- and polyfluoroalkyl substances (PFAS) contaminated soils in a wetland belonging to the Department of National Defence. To preserve the ecological and recreational functions of the site, Golder proposed to evaluate the feasibility of phytoextraction on the site. A phytoextraction test using six indigenous plants was conducted under controlled conditions using soils collected on the site. Preliminary results indicate potential extraction abilities, but also some limitations. Extraction rate are varying with chain-length and this is where the challenge begins: How can we enhance PFAS absorption by the vegetation without mobilizing them to other medias and spread contaminants downstream?

Part 2: Electrochemical Advanced Oxidation Process for the Destruction of PFAS Substances
Ihsen Ben Salah, E2Metrix
Current approaches for removal of PFAS from water to acceptable levels centre around three main traditional technologies: a) adsorption using activated carbon; b) ion exchange; and, c) reverse osmosis. While all three of these technologies can be highly effective, they do not result directly in destruction of PFAS compounds. Although the short-term treatment costs may be low, the long-term cost can become quite high due to solid and liquid disposal costs as well as site management. Electrochemical oxidation represents an alternative and/or a complement for traditional technologies. E2Metrix developed a reactor design (ECOTHOR-AOP) where, much like an airplane engine does with oxygen, micropollutants are concentrated and compressed onto the active anodes and quickly destroyed. This reactor applies electricity to solid state electrodes made from advanced catalyst materials. Wastewater or aqueous waste flows through the reactor. Power is applied to electrodes and the process mineralizes and destroys all types of toxic, recalcitrant organics through multiple oxidation mechanisms. This technology does not use hazardous chemicals and does not produce any solid or liquid waste. Catalyst materials and electrodes are selected depending on the treatment application.

Part 3: A Smoldering Solution to PFAS
David Major, Savron
Savron’s self-sustaining smoldering combustion process (STAR), like what you see in your BBQ, can be initiated to remove PFAS from solid media. A laboratory study funded by US Department of Defense (DoD), through their Strategic Environmental Research and Development Program (SERDP), demonstrated that STAR removed PFAS from solid media (soil and activated carbon) to below detection limits through both destructive (as evident from production of hydrogen fluoride) and conversion to smaller volatile organic fluoride compounds. SERDP is funding future work to improve the mass balance of PFAS destruction and pilot testing at a DoD base.

Part 4: Destruction of PFAS in Water Using Gamma Irradiation
David Patch, Royal Military College of Canada
The same type of irradiation that is used for killing bacteria in food, medical devices and cosmetics can be used to destroy PFAS. A laboratory study in collaboration with the Australian Nuclear Science and Technology Organisation (ANSTO) investigated the use of gamma irradiation to destroy PFAS in aqueous media. Gamma irradiation was found to destroy up to 99% of PFAS with partial conversion into smaller organic fluoride compounds. Future work is planned to investigate effectiveness in aqueous film forming foam (AFFF)-contaminated groundwater and solid media.

Rachel Theriault, Golder Associates Ltd.
Rachel Theriault holds a master's degree in Earth Sciences from the Institut national de la recherche scientifique as well as a bachelor's degree in geography. She joined Golder Associates Ltd. in 2012 as an environmental professional where she specializes in the application of green and sustainable technologies, wetlands and emerging contaminants. Rachel is working to develop expertise on contaminated sites in wetlands and is interested in methods for cleaning up these fragile and biodiversity-rich environments while preserving their integrity as much as possible.

Ihsen Ben Salah, Vice President, Technology and Innovation, E2Metrix
Ihsen Ben Salah is the Vice President of Technology and Innovation for E2Metrix, a Canadian company which has developed ECOTHOR™, an electrolysis technology platform for removing or destroying pollutants in wastewater and process water streams. She is the co-inventor of the majority of the patents regarding ECOTHOR. Ihsen oversees all product development as well as operations, including the start-up of all ECOTHORs. Ihsen holds an undergraduate degree in Engineering (Institut national agronomique de Tunis – Tunisia), a Master’s degree in Oceanography (University of Quebec at Rimouski), a Master’s degree in Environment (University of Sherbrooke) and an Master of Business Administration (University of Sherbrooke).

David Major, Managing Director, Savron
David Major is the Managing Director of Savron, a division of Geosyntec Consultants International, Inc., an Associate Editor of Ground Water Monitoring and Remediation, and Chair of Geosyntec’s R&D program. He has helped develop and commercialize remediation technologies such as zero-valent iron (ZVI) permeable reactive barriers, molecular biomarkers, bioaugmentation cultures, and currently Savron’s smouldering-based combustion technology (STAR). David served on the U.S. Environmental Protection Agency Expert Panel on DNAPL Remediation and the U.S. National Research Council Committee on Geological and Geotechnical Engineering in the New Millennium. He is the recipient of the University of Waterloo Faculty of Science Alumni of Honour Award (2007), Space Hall of Fame® (2007), ASTM C.A. Hogentogler Award (2015), and ICE Telford Premium (2016). He led efforts recognized for national excellence in sustained and innovative academic-industrial collaboration with the Natural Science and Engineering Research Council of Canada Synergy Award in 2009 and 2018.

David Patch, PhD Student and Analytical Technician, Environmental Sciences Group, Royal Military College of Canada David Patch is a PhD student under supervisors Dr. Kela Weber and Iris Koch under the Royal Military College of Canada (RMC). David investigates emerging contaminants in the environment including metallic nanoparticles and, more recently, PFAS. Alongside his PhD role he is also the analytical technician for the Environmental Sciences Group, a research group at RMC. His analytical technician work is also focused on PFAS, with David providing technical and analytical assistance on over fifteen different PFAS projects across the areas of source characterization, fate/transport, and remediation.

Over the last decade, several laboratory-scale evaluations have been conducted using electro-oxidation technology (EO) for the ex-situ treatment of perfluoroalkyl and polyfluoroalkyl substances (PFAS) in water, specifically perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). This technology does not use any chemical products and does not generate any used filters or media or mud. The only consumable is electricity. Results were obtained using boron-doped diamond anodes (BDD). An elimination rate of 91 to 100% was achieved for PFOS (Schaefer et al. 2018, Carter and Farrel 2008) and 93 to 97.48% for PFOA (Urtiega et al. 2015, Zhuo et al. 2015). Operating costs of approximately $16 US/m3 (Nzeribe et al. 2019) were estimated. To our knowledge, no estimation of operating and equipment costs for this technology for the full-scale treatment of PFAS has been presented. The BDD electrode reactors represent a major capital investment in relation to treatment technologies. Furthermore, this capital investment is inversely proportional to the operating costs. It is therefore essential to evaluate both the equipment and operating costs to determine the overall cost. In this presentation, a summary of the theory behind EO BDD electrodes for water treatment will be presented. We will then present the experimental set-up at laboratory scale, the protocol and the results achieved using the new commercial reactor with long-lifespan BDD electrodes for the treatment of actual synthetic water and groundwater contaminated with PFAS. The objective was to achieve the Health Canada criteria for drinking water of 0.2 ppb for PFOA and 0.6 ppb for PFOS. The PFAS analysis was conducted in the analysis laboratory of Dr. Liu of the Civil Engineering Department at McGill University. Our preliminary tests with synthetic water imitating groundwater revealed that 97.1% of PFOA (224 at 6.59 ppb) and 95% of PFOS (553 at 2.92 ppb) can be removed. Other results with real groundwater will be presented in order to achieve the HC criteria and thereby reach an elimination rate of around 99.99% for PFOA and 99.98% for PFOS. The effect of the main operating parameters, such as treatment time, current density and water flow will be presented in order to optimize treatment while reducing the overall cost. Furthermore, the influence of operating conditions such as water temperature, pH, electric conductivity and the initial concentration of PFAS will be examined. The quantification of sub-products such as free and total chlorine and perchlorate will be presented, followed by a strategy aimed at reducing them to a minimum.

In the second part of the presentation, the estimated equipment and operating costs for the new EO BDD reactor for a treatment capacity of 20 m3/d will be compared to an available FPAS treatment technology: granular activated carbon (GAC). The hypotheses for estimating these costs will be revealed. The main objective of sharing these preliminary estimates is to demonstrate the techno-economic feasibility of this new EO BDD reactor in the treatment of PFAS in groundwater by comparing it with GAC.

Valerie Léveillé, Golder Associates Limited
Before joining Golder Associates Limited, Dr. Valerie Léveillé was a process engineer specialized in wastewater electrochemical treatment technologies and then product head at Terragon Environmental Technologies for 9 years. She has been a consultant at Golder since September 2016. During her career, Dr. Léveillé has developed, implemented, troubleshot and optimized domestic wastewater treatment (grey water, raw sewage), the treatment of drinking and industrial water for homes, isolated communities, ships, military bases, schools, mines, food and cosmetic industries. She has also participated in the feasibility of a zero-waste concept for remote northern communities and ships. She has conducted verifications of the physical integrity and safety of wastewater treatment and has prepared technical advice for clients. She is currently participating in water treatment designs and detailed designs, often using the electrocoagulation process. She is the co-author of 3 patents on electrochemical and cold plasma technologies.

Per- and polyfluoroalkyl substances (PFAS) are an emerging suite of compounds that have gathered wide-spread attention but have few remedial options. Research and limited field studies suggest that some reagents have promise for the removal of PFAS from groundwater. Six reagents were chosen for pilot testing including hydrogen peroxide, unactivated sodium persulphate, colloidal activated carbon, powdered activated carbon, biochar and exchange resins to determine if the reagents could be effective at reducing/removing the PFAS. Various PFAS were detected within the pre-treatment groundwater including perfluorodecanesulfonic acid (PFDS), perfluorobutanoic acid (PFBA), perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS) and perfluorononanoic acid (PFNA) with concentrations ranging up to 18,000 ng/L for PFPeA. Six pilot-scale permeable reactive zones (PRZs) were created in a shallow, unconfined aquifer situated in a slightly saline, sulfate-iron reducing environment. The groundwater was also impacted with gasoline-range petroleum hydrocarbons along with various additives including methyl tertiary-butyl ether (MTBE) to tertiary butyl alcohol (TBA).

Each PRZ was created using direct push technology with injection points spaced at 1.5 metre spacing and vertically injected at 0.6-metre intervals to maximize the distribution of the reagents. Groundwater samples for PFAS and other organic and inorganic parameters were collected over an 18-month period (pre-injection, and 3-, 6-, 9-, 12- and 18-months post injection) which represented approximately five pore volumes of flow through the PRZs. Finally, cores were collected from PRZs to evaluate the post-injection distribution of the reagents during the injection process.

The results from the six PRZs suggest that the chemical oxidants, stabilized hydrogen peroxide, and unactivated persulphate were ineffective at attenuating the PFAS compound analyzed with little to no reduction occurring. The results from the adsorption-based PRZs indicated that attenuation of the PFAS was occurring, with the commercial activated carbon (CAC)-based PRZ showing the best performance with all the PFAS analyzed being removed to below their respective detection limits (10 ng/L). The powdered activated carbon (PAC)-based PRZ showed variable treatment while the biochar and ion exchange resin (IER) PRZs initially attenuated the PFAS but then had breakthrough of the C4 PFAS compounds prior to the 6-month post-injection sampling event with the remainder of the PFAS compounds breaking through prior to the 9-month post injection sampling event.

Rick McGregor, President, InSitu Remediation Services Ltd.
Rick McGregor is the President of InSitu Remediation Services Ltd. and has over 26 years’ experience in groundwater and soil assessment and remediation. Rick has worked in over 30 countries and has authored numerous papers on groundwater assessment and remediation. Rick holds a M.Sc. from the University of Waterloo in hydrogeology and geochemistry and is a Certified Ground Water Professional in Canada and the United States.

With limited disposal options for per- and polyfluoroalkyl substances (PFAS)-impacted remediation-derived wastes (IDW) (e.g., spent media, concentrated wastewater), the focus of PFAS treatment technology development has shifted from separation/sorption technologies to combining separation/sorption and destruction technologies. When PFAS are destroyed/completely mineralized to non-toxic products, only minimum waste management is required. Several destruction technologies, such as electrochemical oxidation (EO)/reduction, UV irradiation, sonolysis, and plasma technology, have shown promise for destroying perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) at the bench scale. However, most of these technologies have limited scalability and/or unknown feasibility for treating a wide spectrum of PFAS compounds. The objectives of this project are to understand the impacts of site conditions on EO treatment of IDW, and how to make informed decisions on transitions from bench study to field implementation.

Building upon well-established knowledge on destruction mechanism, reaction pathways and by-products formation published in peer-reviewed articles, the project includes a series of bench-scale studies and a pilot-scale field demonstration to destroy PFAS in a waste stream produced by a regenerable ion exchange resin (IXR) system. The demonstration is underway at a hangar site at a military base where groundwater was impacted by aqueous film forming foam (AFFF) usage. The pilot system consists of a 5 gpm regenerable IXR pilot system for removing PFAS from groundwater, an IXR regeneration system, a methanol distillation unit, and a pilot-scale (5-gal capacity) EO reactor to destroy PFAS in the spent IXR regenerant (also called still bottom). The IXR system will run continuously for three months with monthly regeneration planned. In total, thre batches of EO treatment will be performed (one at a research lab, two batches on-site) to treat about 15 gallons of IXR still bottom. To avoid potential generation of undesired chlorinated by-products, a new chloride-free regenerant has been tested and will be used in this project.

Completed EO treatment laboratory trials for IXR still bottom sample indicated 84% - 95% concentration reduction of PFOA, PFOS, perfluoroheptanesulfonic acid (PFHpS) and perfluorohexane sulfonate (PFHxS) and fluoride generation as an end product. We also found critical structural dependence for PFAS destruction, suggesting that perfluroroalkyl acids (PFAA) precursors and long-chain PFAA are more readily degradable than short-chain PFAA. High total organic carbon (TOC) content in still bottom may impede PFAS destruction through potential competition. Upon completion of the hangar site field demonstration in January 2020, results from the initial three-month field pilot with insights on the impacts of site conditions will be shared. Following the first site demonstration, the system will be mobilized to a fire training area (FTA) site for another two months of groundwater treatment demonstration, and preliminary results will be shared as well.

Shangtao Liang, Environmental Engineer, AECOM
Dr. Shangtao Liang is an Environmental Engineer at AECOM. She has over five years of experience in treatment technology and analytical method development and application for emerging contaminants, including PFAS, in groundwater and soil. She has advanced knowledge in data interpretation, scientific writing, report preparation, and result communication. She is the technical lead of multiple PFAS research and development projects funded by U.S. Department of Defence. She also serves as the technical lead of the AECOM development team for commercialization of AECOM’s proprietary destruction technology (DE-FLUOROTM) for PFAS treatment. She is also the project engineer for multiple PFAS remediation projects at military and industrial sites involving treatability studies and remedial design for complex matrices (e.g., leachate). In addition to project work, Shangtao is a member of the Interstate Technology Regulatory Council (ITRC) PFAS team. Her responsibilities include technical participation on environmental restoration projects, sampling, historical records review, feasibility studies, remedial design and remedial action. Her project experience bridges new technologies with industrial applications and environmental consulting.

Background/Objectives. With the increasing awareness to the widespread contamination of per- and polyfluoroalkyl substances (PFAS) coupled with their resistance to degradation, there is a need for new, low cost strategies to address these contaminants. The current accepted remediation method is to use pump-and-treat systems equipped with activated carbon or a resin, however the costs associated with running these systems and replacing the adsorbent can be exorbitant. Therefore, the ability to implement an in-situ barrier of activated carbon to amend the effective foc of an aquifer and increase the natural retardation factor for these contaminants is an appealing strategy to manage these plumes. This risk-based approach removes PFAS from the mobile phase and eliminates the route of exposure to down-gradient receptors.
This presentation reviews data from multiple field sites where colloidal activated carbon has been utilized to remediate PFAS contamination. Sites discussed include the Solvents Recovery Service of New England superfund site, and a former furniture manufacturing facility in Canada, among others. Further important questions, including the ability to distribute the colloidal activated carbon in the subsurface, the long-term efficacy, and design considerations, will also be addressed.

Approach/Activities.
Multiple field sites were treated with a single application of colloidal activated carbon to address PFAS contamination and other comingled contaminants. Depending on any co-contaminants present, additional remedial agents were also applied to degrade those contaminants. In each case the amendments were applied under low pressure (non-fracking) conditions using direct-push technology. At one of the sites, groundwater was impacted by petroleum hydrocarbons at concentrations up to 6 mg/L in addition to perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) which were present at baseline concentrations of 300 to 3,300 ng/L. In this case, an oxygen release agent was co-applied to promote the biodegradation of the total petroleum hydrocarbons (TPH). At another site, trichloroethylene (TCE) was present in addition to the PFAS contamination and a sulfidated zero-valent iron was co-applied with the colloidal activated carbon. Monitoring at all sites is on-going, with current data ranging from three months to over two years, and has included analysis of PFOS, PFOA, shorter chain PFAS, and co-contaminant concentrations.

Results/Lessons Learned.
Results from field case studies have demonstrated immediate removal of PFAS from the dissolved phase to levels below the US Environmental Protection Agency health advisory level when treated with a single application of colloidal activated carbon. The site with the longest monitoring period has maintained its performance with PFOS, PFOA, as well as shorter chain species for over two years and counting. The colloidal activated carbon treatments, sometimes in conjunction with another remedial agent, can address co-contaminants like TPH and TCE. Overall, these 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.

Maureen Dooley, Northeast Region Manager, REGENESIS
Maureen Dooley has over twenty-five years’ experience in many aspects of environmental industry including project management, research and development, senior technical oversight, remedial design and laboratory management. Maureen’s current position is the Northeast Region Manager for REGENESIS. She is responsible for managing both sales and technical support associated with REGENESIS bioremediation and chemical oxidation products. As part of her responsibilities at REGENESIS she has reviewed hundreds of potential projects and provided recommendations for remediation. Much of her work over her career has been focused on the development and implementation of bioremediation programs.

Over the past several years, however, she has been focused on chemical oxidation applications at petroleum and chlorinated hydrocarbon sites. Maureen has drafted hundreds of project proposals, evaluations and reports related to the feasibility of using bioremediation. In addition, prior experience includes the completion of numerous treatability studies designed to evaluate the biodegradation of a wide range of chemical constituents that include chlorinated solvents, petroleum hydrocarbons, explosives, aromatic hydrocarbons and pesticides.

We evaluated the relationship between microbial communities and per- and polyfluoroalkyl substances (PFAS) distributions in the subsurface at a firefighting training area (FFTA). Aqueous film forming foam (AFFF) was applied to the FFTA for over 50 years, a time period which spans many different AFFF manufacturer formulations. A suite of PFAS encompassing C4-C12 (carboxylates, sulfonates), perfluorooctanesulfonamide (PFOSA), and 8:2, 6:2 telomers were profiled in 40+ wells over a two-year period yielding over 80 samples total. Microbial communities from these same samples were also characterized using next generation sequencing and this data analyzed in conjunction with PFAS profiles, available site data (e.g., subsurface stratigraphy), monitoring well data (e.g., pH, oxidation-reduction potential (ORP), inorganic species) and soil data (e.g., soil type, organic carbon). Using the described data, in addition to total odixzable precursor (TOP) assay data, our data indicates and supports current hypotheses that PFAS telomer transformations occur onsite. Additionally, we found several correlations indicating positive, negative, and sometimes threshold inhibition relationships between certain PFAS and specific microbial genera. This roadmap of specific genera could be used to further investigate and develop genera involved in the transformation of PFAS in the subsurface.

David Patch, PhD Student and Analytical Technician, Environmental Sciences Group, Royal Military College of Canada
David Patch is a PhD student under supervisors Dr. Kela Weber and Iris Koch under the Royal Military College of Canada (RMC). David investigates emerging contaminants in the environment including metallic nanoparticles and, more recently, PFAS. Alongside his PhD role he is also the analytical technician for the Environmental Sciences Group, a research group at RMC. His analytical technician work is also focused on PFAS, with David providing technical and analytical assistance on over fifteen different PFAS projects across the areas of source characterization, fate/transport, and remediation.