Emerging Contaminants: Investigation and Remediation of Poly- and Perfluoroalkyl Substances in the Environment - 17339

The group of chemicals known as PFAS (poly- and perfluoroalkyl substances) has come under increasing scientific and regulatory scrutiny in recent years as more is understood about their toxicity, their environmental persistence and their potential to bio-accumulate. PFAS are used in a wide range of industrial applications and commercial products due to their unique surface tension and levelling properties. They include stain repellents for textiles and carpeting, grease-proof paper, water- and oil-resistant coatings, and mist suppressants. PFAS are also major components of the class B fire fighting foams known as aqueous film forming foam (AFFF), Fluoro-protein Foams (FP) and Film Forming Fluoro-protein Foams (FFFP) commonly used at Federal and Commercial facilities throughout the world. Long chain PFASs (>5 or 6perfluroalkyl-carbons) such perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), bio-accumulate. Currently, PFOS, PFOA, and a few other PFASs are increasingly regulated outside of the U.S., and at varying levels in drinking water or groundwater in select U.S. states. The U.S. EPA recently established a long-term exposure criteria of 70 ng/L for combined PFOS and PFOA in drinking water. While PFOS and PFOA have the most regulatory attention, there are thousands of chemicals in the PFAS class; some PFASs are precursor compounds capable of transforming to PFOS and PFOA or analogs. The remedial options available to address PFAS contamination are limited by the unique physico-chemical properties of these compounds. Technologies currently used for the remediation of PFAS contaminated sites include soil incineration or excavation to landfill, and groundwater extraction with PFAS adsorption onto activated carbon or resins. Emerging technologies for PFAS, include stabilization in soil, photolysis/ photo-catalysis, reductive decomposition, advanced oxidation, reduction and sonolysis for groundwater. However, the evidence that these technologies effectively break the fully fluorinated backbone of PFAS, or can treat or sequester all carbon chain lengths is limited. To date these technologies are unproven or considered infeasible for high flowrate, low concentration applications. New in-situ techniques, including an oxidation / reduction method known as ScisoR^R (Smart combined in situ oxidation and Reduction), are currently being tested in the lab and some are being applied in field demonstrations. (authors)