Strength under pressure: Aerobic granular sludge (AGS) dynamics in sequencing batch reactors exposed to per- and...

This study investigated the capacity of aerobic granular sludge (AGS) to remove per- and polyfluoroalkyl substances (PFAS). Over 247 days, AGS in two sequencing batch reactors (R1-CTRL and R2-PFAS) was tested with synthetic wastewater containing four representative PFAS compounds (PFPeA, PFOA, PFBS, PFDS) chosen for their diverse properties, including chain length and hydrophobicity. The PFAS-acclimated reactor (R2-PFAS) exhibited greater resilience and improved performance compared to the control (R1-CTRL). Both reactors achieved > 95 % removal of chemical oxygen demand (COD), ammonia, and phosphate, despite PFAS concentrations reaching 500 µg L^-1. However, R1-CTRL experienced declines in biomass and settleability, while R2-PFAS maintained stability and a more consistent extracellular polymeric substances (EPS) profile, suggesting tolerance to PFAS. PFAS removal varied by compound. Nearly 100 % removal efficiency was achieved for PFDS, while PFPeA, PFBS, and PFOA showed variable results (- 71 % to 93 % in R1-CTRL; - 17 % to 100 % in R2-PFAS). The findings demonstrate AGS as a promising tool for PFAS removal, particularly when biomass is acclimatized during granulation. This approach could enhance wastewater treatment efficiency and effluent quality.