Optimizing Per- and Polyfluoroalkyl Substance Removal from Aqueous Film-Forming Foam-Impacted Airport Stormwater Runoff: Adsorber Bed Design

Per- and Polyfluoroalkyl substances (PFASs) are commonly detected in airport stormwater runoff due to historical and ongoing use of aqueous film-forming foams (AFFFs). Conventional stormwater control measures (SCMs) are generally effective at removing PFASs associated with the particulate fraction, but may provide limited removal of dissolved-phase PFASs. Sorbent polishing beds represent a potential downstream treatment option; however, their applicability and performance for PFASs in stormwater have not been well studied. In this study, measured PFAS concentrations and runoff volumes from an AFFF-affected airport apron were combined with literature-derived sorption parameters to develop a screening-level framework for evaluating adsorber beds as polishing units for SCM effluent. Bed sizing was calculated using a representative empty bed contact time (EBCT) of 10 min and a design volume based on the 85th percentile storm event. Sorbent performance was evaluated using literature equilibrium partition coefficients (Kd) for activated carbons, ion exchange resins, and specialty materials to estimate operational lifetimes prior to regeneration or replacement. Model-based results indicated lifetimes ranging from approximately 7 years for activated carbon to more than 50 years for specialty materials, depending on PFAS chain length and affinity. Sensitivity analysis using quartile Kd ranges showed predicted lifetimes spanning orders of magnitude, emphasizing the screening-level nature of the estimates. This work links field monitoring data with conceptual adsorber design to support early-stage evaluation of sorbent polishing strategies for airport runoff management, supporting compliance under tightening discharge regulations.