Field demonstration of polymer stabilized activated carbon for in situ treatment of per- and polyfluoroalkyl substances (PFAS)-impacted groundwater

In situ remediation of groundwater impacted by per- and polyfluoroalkyl substances (PFAS) is challenging due to their resistance to destructive processes and the need to meet part-per-trillion (ng/L) drinking water standards. This study involved a field demonstration of a polymer-stabilized activated carbon (hereafter referred to as colloidal carbon product-CCP) using a “push-pull” test, consisting of a “push” phase (CCP injection) and a “pull” phase (withdrawal of treated groundwater), to assess the effectiveness of the treatment technology. A laboratory-scale aquifer cell experiment using site aquifer materials and simulated groundwater demonstrated 90.9 to > 99.9% removal of all six tested PFAS by CCP injection. For the field-scale test, a total of 1900-L CCP was injected into a 2.4-meter interval, and 4750 L of water were extracted from the treated interval, with extractions conducted at 3- and 10-months post-injection. Concentrations of PFAS were reduced by up to four orders-of-magnitude, from > 50,000 ng/L total PFAS to below individual detection limits in samples collected 10 months post-injection. An economic analysis indicates that operating costs of the CCP system would be less than half of a comparable “pump-and-treat” system. These findings demonstrate that CCP injection is a practical, efficient, and cost-effective in situ remediation strategy for addressing PFAS-impacted groundwater plumes.