Effects of Per- and Polyfluoroalkyl Compounds (PFASs) on Anaerobic Granular Sludge: Methane Production and Microbial Community Composition.

PFASs are a group of pollutants ubiquitous in the environment, for which their effects on the microbial community composition and activity of anaerobic granular sludge are still poorly understood. With our study, we aimed to provide insight into the impact of four PFASs on the methane yield of anaerobic granular sludge (AGS) using acetate as the substrate. Anaerobic granular sludge was exposed to different concentrations of 1H,1H,2H,2H-Tridecafluorooctan-1-ol (6:2FTOH), 1H,1H,2H,2H-Perfluoro-1-decanol (8:2FTOH), Tridecafluorohexane-1-sulfonic acid (PFHxS) and Perfluorooctanoic acid (PFOA). While the two fluorotelomers caused marginal changes in methane production, PFHxS and PFOA greatly inhibited acetoclastic methanogenesis. Depending on the concentration, the AGS could recover its activity after a certain number of hours when incubated with PFASs. The 50% Inhibitory Concentration (IC50) of the methane production was estimated to be 278.98 (± 3.2) mg/L for PFOA and 1,091.9 (± 26.78) mg/L for PFHxS. PFASs exposure also influenced the archaeal and eubacterial communities. The most significant change was observed with the eubacterial community, which showed an increase in the relative abundance of the genus Sulfurospirillum in the samples treated with 2,000 mg/L of 8:2FTOH and 600 mg/L of PFOA, whose presence grew to represent 16.65% and 45.4% of all reads in those samples. These findings provide insight into the differential impact of PFASs on methanogenic processes and highlight their potential to disrupt key microbial functions in anaerobic systems.