Spatiotemporal profiling of antimicrobial agents during wastewater treatment – a national study

• 55 antimicrobials tested at 10 WWTPs spatially distributed in the UK in a one-year longitudinal study • Significant temporal and spatial variability observed with winter having higher daily AA loads • WWTP treatment efficiency highly variable, AA group dependent, with no preference for any technology observed • Lincosamides, macrolides, nitrofurans with removal >75%; B-lactams, glycopeptides with 75% removal of lincosamides, some macrolides, nitrofurans, and <75% removal of β-lactams, glycopeptides, with some macrolides and sulfonamides being highly variable. Quinolones had very low removals with mean and median removal rates of –31.7 and –3.7%, respectively. Furthermore, comparison between trickling filter and activated sludge systems, which are the two most common biological treatment processes employed in the UK, suggests that trickling filter systems had comparable or even higher removal rates than the activated sludge systems for most AAs, except for azoles. Furthermore, due to the high variability in AA removal, no significant differences were observed in the overall removal efficiency among the tested sampling sites or across the same technologies. This indicates substantial heterogeneity in AA removal and highlights potential challenges in optimizing wastewater treatment performance for improved AA removal.