Committed to furthering our understanding of treatment technology for Per- and Polyfluoroalkyl substances (PFAS), our environmental team publishes research on the effectiveness of alkaline ozonation on removing PFAS present in groundwater.
There are no simple solutions to addressing PFAS, as discussed previously by our water and environmental team in 5 critical PFAS insights. It is more and more evident that effective and sustainable remedial technologies are necessary to treat PFAS in all impacted media, including drinking water sources, but testing technologies are still in the preliminary developmental stages. Environmental experts face numerous challenges associated with PFAS remediation, such as accurate analytical detection, competing compounds at higher concentrations, and cost effective and timely testing. Evolving innovations and technologies are occurring in this space to address regulatory landscapes and push towards lower concentrations.
Innovative remediation technologies are required to provide a toolbox of options for PFAS treatment, particularly at complex sites where other contaminants are present that can inhibit treatment.
June 2020 GHD PFAS study ‘Evaluation of PFAS treatment technology: Alkaline ozonation’ looks at one such vein of possible solutions. Published online in Remediation - the Journal of Environmental Cleanup Costs Technologies & Techniques, this peer-reviewed article includes research conducted in collaboration with our partners from Revitalizing Auto Communities Environmental Response (RACER) Trust and Clarkson University.
About the Study
At GHD's Innovative Technology Group (ITG) laboratory in Niagara Falls, New York, a bench-scale treatability study was performed to evaluate the effectiveness of alkaline ozonation on removing PFAS present in groundwater at a former industrial site identified in the study, located in Michigan.
Due to the ubiquitous nature of PFAS, specific sampling procedures regarding field/laboratory equipment, clothing, personal protective equipment, and sample containers were maintained to avoid external influences impacting PFAS results. The groundwater tests were conducted using representative samples of groundwater collected from the site in high-density polyethylene (HDPE) containers with unlined lids. PFAS-spiked tests were conducted with certified PFAS-free water that was spiked with different concentrations of PFOS.
The study involved testing the PFAS-impacted groundwater under alkaline ozonating conditions under a range of experimental conditions, including modifying pH, hydrogen peroxide-to-ozone molar ratio doses, length of ozonation pretreatment times, and sampling techniques. PFAS-spiked samples were used to determine if destruction byproducts such as inorganic and organic ions were generated resulting from PFAS treatment. Our benchmark for success is to evaluate and compare results to the new Michigan maximum contaminant levels (MCLs).
Results
Based on the current and previously published studies on alkaline ozonation for PFAS treatment, alkaline ozonation may prove to be a viable PFAS treatment technology for long-chain (PFNA, PFOS, and PFOA) and some short-chain (PFPeS, PFHxS, and PFHpS) PFAS at full scale.
The results from all tests indicated that decreases in PFAS concentrations were due to a combination of removal and destructive mechanisms with enhanced removal under acidic pH ozonation pretreatment conditions. Short-chain PFAS concentrations increased during the experiments followed by an overall decrease in concentration under continuous alkaline ozonation conditions. Reductions in concentrations in PFOS of 75–97% were observed against the initial concentration. Reductions in concentrations were also observed in other PFAS such as 6:2 FTS, PFHxS, PFOA, and PFNA.
Conclusion
Treatment of PFAS under the conditions discussed in this study suggests that alkaline ozonation may be a viable remediation option for PFAS-impacted waters.
“To our best knowledge, this is the first time that alkaline ozonation has been performed on PFAS-impacted water while monitoring a larger suite of PFAS analytes in addition to destruction byproducts,” shares Beth Landale, GHD Principal and contributing author of the paper. “In an industry demanding answers, the ability to share research and build collective knowledge, is vital.”
Meet the Study Author
Meet Beth
Beth Landale is a Principal and Project Director for GHD in the Detroit, Michigan office. She is a registered professional engineer in Ontario and Michigan. Her 19-year career has been focused on environmental investigations and remediation, which include numerous groundwater, soil, LNAPL, DNAPL and vapor intrusion assessments, as well as remediation design and implementations including in situ and ex situ groundwater treatment. Beth is a member of the GHD PFAS North American steering committee, which is used as an internal resource throughout the organization and works with external partners to evaluate treatment technologies. Her most recent PFAS project includes the evaluation of several PFAS remediation technologies for treatment of an existing groundwater collection system. Contact Beth at beth.landale@ghd.com | T: 1 248 893 3400
How can we help?
Our experienced global water and environment teams are working together to provide comprehensive, practical, risk-based solutions to our clients including site investigations and development of conceptual site models, risk assessments, and innovative control and remedial technologies. We track the fast changing regulatory and technical aspects of PFAS at both the state and federal levels, and is committed to sharing all the latest insights.
