Remediation of Poly- and Perfluoro Alkyl Substances: New Remediation Technologies for Emerging Challenges

Background/Objectives. Poly- and perfluoro alkyl substances (PFAS) comprise a diverse class of contaminants which include PFOS (perfluorooctane sulfonate) and PFOA (perfluorooctanoic acid). PFAS are not amenable to bioremediation or conventional chemical oxidation and are difficult to remediate in situin soil and groundwater systems. Further complicating the remediation challenges are the presence of precursor PFAS that are often present at locations where class B firefighting foams has been released and are not analysed for by standard analytical laboratory methods (US EPA method 537). These precursors can act as a source of perfluorinated carboxylates and sulphonates, as some precursors are less mobile but they all will biotransform over time forming perfluorinated compounds as dead end daughter products.

Approach/Activities. Innovative and emerging remediation solutions for PFAS include a number of types of technologies to address highly concentrated source zones, mitigate mass flux of impacts to aquifers or address PFAS in abstracted water. Use of granular activated carbon (GAC) to treat PFAS will only effectively remove a proportion of these contaminants from groundwater, whilst offering a very low binding capacity for PFOS (as compared to hydrocarbons), so can be costly. Challenges of more comprehensive PFAS treatment in water are currently addressed using technologies such as reverse osmosis or nano-filtration. There are new precipitation technologies for water treatment such as PerFluorAd, novel ion exchange resins, sonolysis, generation of solvated electrons, thermal approaches and sorptive media which show promise and will be summarized.

Results/Lessons Learned. Recent results from laboratory trials with several technology will be presented.