Aims: Our purpose was to clarify the effect of sulfamethoxazole (SMX) on the start-up period, particle formation, and treatment efficiency of an aerobic granular sludge system.
Methods And Results: We compared an R1 granular sequencing batch reactor (GSBR) started with 5 μg L SMX and an R2 GSBR started without SMX, as a control, to investigate the impact of a trace amount of SMX (5 μg L ) on aerobic granular sludge (AGS) characteristics and the removal of conventional contaminants. AGS granulation in the R1 system was not inhibited by SMX, but the granule particle size was smaller than that in the R2 system.