Battelle Memorial Institute
Dr. Ramona Darlington is a Senior Research Scientist on the Battelle Environmental Services team. An experienced Remediation Engineer, Ramona works with government and commercial clients to evaluate environmental contamination and develop remediation plans for challenging contaminants, including PFASs.
PRACTITIONER WORKSHOP PANELIST
Regeneration of Concentrated Waste Streams
Novel method to regenerate PFAS contaminated Granular Activated Carbon
PFAS compounds are in firefighting foams and as a result their contamination is widespread across DOD bases. With the emerging evidence of PFAS toxicity, federal and state agencies have been issuing drinking water advisories. Recent EPA guidelines (2016) established the advisory level for combined PFOA and PFOS concentration in drinking water at 70 parts per trillion (ppt). Currently to remove PFAS from drinking water GAC is the only acceptable method used. The challenge with GAC is there is currently no method of regeneration and to dispose of the spent GAC requires incineration which is both high energy intensive and costly. DOD is interested in alternate technologies to regenerate GAC. This presentation investigates GAC regeneration and performance of regenerated GAC in adsorbing PFOA and PFOS. The current understanding is that hydrophobic interaction is the dominant adsorption mechanism of PFAS on GAC. Literature review on the interaction of PFAS with natural particles supports the theory of the hydrophobic sorption mechanism. It was observed that the partitioning coefficient of fluorinated surfactants between natural particles and water increase with the length of hydrophobic tail of the surfactants. Polar solvents sonochemical and electrochemical methods were used to remove PFAS from GAC. The approach included first sorbing PFAS onto virgin GAC and developing sorption isotherms. Then different methods were used to remove the PFAS from GAC. Once successful at removing the PFAS sorption isotherms were prepared with the regenerated GAC to compare performance. This presentation will provide the results of these experiments.