Removal of sulfamethoxazole (SMX) in sulfate-reducing flocculent and granular sludge systems

This study investigated sulfamethoxazole (SMX) removal and fate in sulfate-reducing up-flow sludge bed (SRUSB) reactors inoculated with sulfate-reducing bacteria (SRB) granules and flocs. The resilience of SRB granules and flocs against varying pHs and hydraulic retention times (HRTs) was also examined. SRB granules and flocs efficiently removed SMX from wastewater, which was significantly higher than the aerobic sludge. SRB granules achieved significantly (p < 0.05) higher SMX removal (similar to 13.3 mu g/g suspended solids (SS)-d) than the SRB flocs (similar to 11.2 mu g/g SS-d) during 150-day of SRUSB reactors operation. The SMX removal by both granules and flocs was mainly attributed to biodegradation. Sorption also contributed to SMX removal, in which aromatic protein-like substances of extracellular polymeric substances played important role in SMX removal. In addition, SRB granules showed higher resilience than SRB flocs against varying pHs and HRTs. Thus, SRB-mediated biological process, especially SRB granules, could be a promising biotechnology to remove SMX from waste-waters.