Abstract: Per- and polyfluoroalkyl substances (PFASs) comprise a diverse class of contaminants, which include PFOS (perfluorooctane sulfonate) and PFOA (perfluorooctanoic acid). PFASs are not amenable to bioremediation or conventional chemical treatment, and this limits in situ remediation options. PFAS are relatively ubiquitous in the environment at low concentrations, but source areas exhibit higher PFAS concentrations. While the USEPA Health Advisory Limit of 70 nanograms per liter for the summation of PFOA and PFOS is not a maximum contaminant level (MCL), to be protective of potential beneficial reuse aquifers, PFAS groundwater plumes emanating from source zones will require some form of active management. The use of conventional sorbents, such as granular activated carbon (GAC) and anion exchange (AIX) resins, to address PFASs in water have become a “de facto” interim measure in response to immediate needs for PFAS removal from drinking water. Challenges of more comprehensive PFAS treatment in drinking water may also be addressed using technologies such as reverse osmosis or nano-filtration. Extending these technologies to extracted groundwater for remediation purposes, which have various degrees of geochemical and co-contaminant competition, often requires a treatment train, combining conventional sorbents and engineered filtration with more innovative and emerging remediation solutions for PFASs. These emerging solutions include many types of technologies to address source zones, mitigate mass flux in aquifers, or address PFASs in extracted water to improve the efficiency of conventional drinking water treatment technologies. There are new flocculation technologies, novel AIX resins, new engineered sorptive media, electrochemical oxidation, electrocoagulation, sonolysis, and advanced oxidation processes combined with advanced reductive processes. Remediation technologies for PFAS source zones in soil are primarily limited to excavation with onsite or offsite incineration and in situ soil stabilization. For in situ soil stabilization to be considered viable, ongoing research and development is being conducted to evaluate the longevity of fixation amidst circumneutral pH and biotransformation, which may enhance PFAS dissolution. Remediation of PFAS source zones and the associated groundwater plumes presently requires multiple technologies to protect human health in a cost-conscious manner. An investment in research and development to explore new technologies is part of a key initiative for groundwater preservation and protection of human health. The technologies discussed here will be presented, and their applicability/readiness to the remediation market will be assessed.
Bios: Erika Houtz, PhD, PFAS Analytical Lead at Arcadis. Dr. Houtz has eight years of academic and professional experience investigating the environmental impacts of PFASs. She has developed analytical and experimental methods for the measurement of PFASs in environmental and human samples and has investigated and published on the fate and transport of PFASs in natural and engineered systems, with a particular emphasis on the fate of PFASs found in aqueous film forming foams. Dr Houtz received her PhD in environmental engineering from University of California, Berkeley and her BS in chemical engineering from Ohio State University.
Jeffrey McDonough, M.S., P.E. Principal Environmental Engineer at Arcadis. Mr. McDonough graduated from Penn State University in 2005 and 2006 with a Bachelor’s of Science in Civil and Environmental Engineering and a Master’s of Science in Environmental Engineering, respectively. Jeff began working for Arcadis in 2007 in Newtown, PA, and continued working for Arcadis in San Francisco, CA (2011-2016), and now in Portland, ME. As a Principal Environmental Engineer, Jeff specializes in remediation of a wide variety of compounds over a global footprint. Currently, Jeff’s focus for Arcadis is on poly- and perfluoroalkyl substances as the North America co-leader within Arcadis’s Technical Knowledge & Innovation pillar.