PFAS Experts Symposium 2: PFAS Remediation research – Evolution from past to present, current efforts, and potential futures

Abstract

Due to the diverse chemistries of per‐ and polyfluoroalkyl substances (PFAS) and their apparent recalcitrance to natural biological and abiotic transformation processes, remediation of this class of compounds in groundwater environments is much more challenging than that of other common contaminants such as chlorinated solvents, hydrocarbons, methyl tert‐butyl ether, and 1,4‐dioxane. Overall, the groundwater remediation community is faced with substantial challenges that will require both continued enhancement of existing technologies and development of new technologies and strategies to manage PFAS‐impacted sites. Fortunately, an extraordinary breadth and depth of ongoing research in PFAS remediation is funded through a variety of different agencies and organizations. This research can be organized into three main categories: (1) nondestructive approaches that remove PFAS from water and other matrices; (2) destructive technologies that break carbon–fluorine and carbon–carbon bonds to create nontoxic products; and (3) coupled systems that concentrate and then destroy PFAS. As with previous groundwater contaminants, an initial focus on ex situ PFAS treatment is now slowly evolving to include more in situ research. However, as of 2021, there are no practical groundwater remediation technologies that have been shown to destroy target PFAS (i.e., mineralize and/or create nontoxic products) in situ at full‐scale field application. While the historical goal of in situ treatment for most contaminants has been destruction, practitioners, facility owners, and regulators may need to alter their expectations and objectives for PFAS, at least in the short term, to management strategies that include treatment at receptor locations to avoid exposures and adsorption‐based attenuation strategies for some plumes. These approaches can be used as practical alternatives to PFAS destruction or to buy time until promising technologies become both commercially available and accepted by the industry. The success of any remedial effort typically depends upon meeting regulatory criteria, which in the case of PFAS, are currently in flux at the federal level and differ by orders of magnitude among state regulatory bodies. While this is understandable given the uncertainty and complexity of this issue, setting firm, consistent, and attainable regulatory standards is necessary to provide researchers and practitioners with necessary benchmarks for remediation technology development and commercialization.

Early breakthrough of short‐chain perfluoroalkyl substances in adsorptive media treatment

“…Maintaining similar laboratory analytical detection limits throughout the study to achieve data comparability is also recommended (Thomas et al., 2020). Furthermore, treatability studies can support the identification of PFAS treatment technologies by defining appropriate expectations for overall technology performance (Newell et al, 2022). As demonstrated in this study, performing batch sorption experiments alone without column studies is not an effective approach to help evaluate potential adsorptive technologies for field implementation.…”

Climate‐influenced hydrobiogeochemistry and groundwater remedy design: A review

“…This is an important topic not just because of the potential degradation of PFAS directly or indirectly from current or future biological processes (Berhanu et al, 2022; Zhang et al, 2021), but also because some PFAS and PFAS precursors (i.e., compounds that have the ability to form PFAS) have potential to transform to constituents that may have different and more challenging toxicological, mobility, and fate profiles (Liu & Mejia Avendaño, 2013; Shahsavari et al, 2021). Finally, an important consideration that exists regarding PFAS is whether the global distribution and occurrence of these chemicals in the environment will continue to be exacerbated by shifting climatic (e.g., wind patterns and extreme events) conditions because of their relative stability and very slow (if not negligible) degradation under ambient environmental conditions (Newell et al, 2022).…”

Enhanced attenuation (EA) to manage PFAS plumes in groundwater

“…Based on the PFAS Experts Symposium II meeting, Newell et al (2022a) outlined three broad scenarios for how remediation of PFAS plumes may evolve over the next several years: Under Scenario 1, the most common groundwater remediation technology, pump and treat, and an emerging technology, in‐situ injection or emplacement of sorbents, could be applied at every PFAS groundwater site where some form of plume control is required. …”

“…Overall, Scenario 3 was suggested to be the most likely path forward for groundwater remediation in Newell et al (2022a). While some PFAS sites may be managed with natural retention processes alone, other sites may require near‐term, higher energy response measures to protect potential receptors.…”

“…Based on the PFAS Experts Symposium II meeting, Newell et al (2022a) outlined three broad scenarios for how remediation of PFAS plumes may evolve over the next several years:…”