Bench Test Using OxyZone® on Fluorinated Compounds in AFFF Contaminated Groundwater
In-Situ Chemical Oxidation (ISCO) using OxyZone® has been used to bring sites with persistent and recalcitrant contaminants to closure. In this case study, OxyZone® has been demonstrated to be an effective treatment method to destroy Poly and Per Fluoroalkyl Substances (PFAS) in aqueous film-forming foam (AFFF) contaminated groundwater.
Site: Fire Training Area, Massachusetts
Contaminant: PFAS (PFOS and PFOA)
Geology: Permeable sand and gravel Challenge: Destroy PFAS in AFFF contaminated Water
Remediation: OxyZone® ISCO process
In 2015, PFAS, predominantly perfluorooctane sulfonate (PFOS), was discovered in the drinking water wells downgradient from the AFFF fire training area in concentrations greater than the 2016 USEPA Health Advisory levels. An existing pump and treat system was reactivated and the PFAS contaminated groundwater was treated with granulated activated carbon (GAC). The GAC requires periodic regeneration to remove the PFAS from the carbon. The site manager contacted EnChem Engineering to perform a bench scale treatability test using OxyZone® onsite groundwater from two different portions of the source area contaminated with AFFF.
The test results show 99% removal of PFOS and an overall 70% PFAS removal after 9 hours of treatment. Six of the fifteen detected PFAS compounds were removed to below detection limits ranging from 0.1-0.2 ppb. Most interesting was that, for one groundwater source, the amount of fluoride released was almost eight times the amount of fluoride contained in the identified PFAS. This can be explained by the presence of a significant amount of other, un-identified PFAS associated with the AFFF in the groundwater. Based on the bench scale treatability tests, OxyZone® can significantly destroy PFAS insitu in groundwater and the sorbed fraction in the aquifer matrix. This in-situ approach would greatly reduce remediation time and eliminate the need for offsite disposal spent GAC or other media.