Permeable Reactive Barrier Treatment of 1,4‐Dioxane and PFOA Impacted Groundwater Using Powdered Activated Carbon (PAC) Activated Persulfate

ABSTRACT Per‐ and polyfluoroalkyl substances (PFAS) and 1,4‐dioxane are emerging groundwater contaminants that persist in the environment, are challenging for in‐situ treatment methods, and have been detected in drinking water systems throughout the United States. The objective of this study was to evaluate a permeable reactive barrier technology that employs powdered activated carbon (PAC) to achieve both persulfate activation and adsorption for in situ treatment of PFAS and 1,4‐dioxane contaminated groundwater. The scientific question specifically addressed by this study is the effectiveness of PAC as an alternative activator for persulfate in degrading persistent pollutants like 1,4‐dioxane and PFAS in contaminated groundwater and soil. In column studies, persulfate activation using PAC was more effective than iron sources (pyrite, ferrihydrite, or FerroBlack), and resulted in degradation of both 1,4‐dioxane and PFAS. 1,4‐dioxane was readily oxidized, regardless of the activation source. No PFAS removal occurred in studies with iron‐activated persulfate, whereas PAC activation of persulfate resulted in 99.9% removal of PFOA. In column studies packed with sand or aquifer materials and persulfate, removal of 1,4‐dioxane and PFOA continued after the persulfate and sulfate anions were no longer detected in the effluent, indicating the PAC may have retained the capacity to adsorb the co‐contaminants. These findings suggest that PAC‐activated persulfate treatment in permeable reactive barriers could be a viable method for remediating multiple groundwater contaminants and warrant further investigation in field‐scale studies.