PFAS Destruction and Air Emissions During Full‐Scale Thermal Reactivation of PFAS‐Laden Granular Activated Carbon From Industrial Sources

ABSTRACT

Granular activated carbon (GAC) is widely recognized as a best available technology (BAT) for the removal of per‐ and polyfluoroalkyl substances (PFAS) from both drinking water and wastewater—capable of achieving the low nanogram per liter (ng/L) effluent concentrations required for regulatory compliance. PFAS removal is achieved through adsorption within the extensive internal pore structure of the GAC. Once the GAC reaches its adsorption capacity for PFAS—otherwise denoted as spent GAC—standard practice is to return the spent GAC to a thermal reactivation facility. Thermal reactivation is a high‐temperature process that removes adsorbed contaminants from GAC and restores internal pore structure for subsequent reuse. As PFAS regulatory requirements continue to become more stringent, there is an increasing need for transparency regarding the fate of PFAS during thermal reactivation of spent GAC, including consideration of greenhouse gas emissions and the potential formation of products of incomplete combustion and products of incomplete destruction (PICs/PIDs). A comprehensive testing plan was conducted at a full‐scale facility treating PFAS‐laden spent carbon from industrial treatment sources to demonstrate both the degree of PFAS destruction and to test for the presence of PICs/PIDs in process emissions. The study utilized U.S. Environmental Protection Agency (U.S. EPA) OTM‐45, U.S. EPA OTM‐50, and U.S. EPA Method 0010/8270 with inclusion of fluorinated PICs/PIDs to fully characterize vapor‐phase emissions from the reactivation process. Reactivated carbon samples were below the limits of detection for 72 PFAS analytes. The process achieved both destruction and removal efficiency (DRE) and destruction efficiency (DE) of > 99.999% for total analyzed PFAS with > 99.9999% DRE observed for individual PFAS. Stack emissions were below the detection limits of U.S. EPA OTM‐50 and U.S. EPA Methods 0010/8270 demonstrating the absence of select PICs/PIDs in emissions at standard operating conditions. Together, these findings demonstrate that full‐scale thermal reactivation can reliably achieve high levels of PFAS destruction while processing highly loaded spent GAC without the release of undesirable byproducts.