Evaluation of sulfamethazine sorption and biodegradation by anaerobic granular sludge using batch experiments

This study investigated the removal of the veterinary antimicrobial sulfamethazine (SMZ) using anaerobic granular sludge in batch tests. Adsorption and biodegradation were the main mechanisms involved, with adsorption being properly described by a pseudo-second-order model and a linear adsorption isotherm. The adsorption rate constant ranged from 0.00051 to 0.00587 L µg(-1) h(-1), whereas the SMZ partition coefficient was determined to be 0.0717 L g TVS(-1). Biodegradation depended on the presence of readily available organic matter, indicating the occurrence of cometabolism. The addition of exogenous COD to a 144-h batch run at the concentration level of 100 µg L(-1) increased the efficiency of SMZ removal from 57 to 84%. A two-compartment model was developed and fitted to the experimental results, which established the aqueous phase as the main bioavailable compartment. The results suggested that SMZ conversion in anaerobic reactors benefits from high influent dilution and an exogenous supply of organic matter.