The removal of veterinary antibiotics in the high-rate anaerobic bioreactor: continuous and batch studies

Abstract

Veterinary antibiotics in swine wastewater has drawn great public attention. The removal processes of sulfamethizole (SMZ), enrofloxacin (ENR) and chlortetracycline (CTC) were investigated in the high-rate anaerobic process. The continuous experiments demonstrated that in 3 L working volume and with the organic loading rate 5 kg/(m3·d) rised to 20 kg/(m3·d), the average removal efficiencies of the high-rate anaerobic bioreactor for SMZ, ENR and CTC were 0, 54 and 100%, respectively. By using fixed-bed adsorption models, the saturation time of SMZ, ENR and CTC were 4 hydraulic retention time (HRT) (24 h), 8 HRT (48 h) and 372 HRT (2,232 h). In the batch experiments, the adsorption and biodegradation characteristics of anaerobic granular sludge were determined. In the high-rate anaerobic bioreactor, SMZ removal process mainly relied on the adsorption but it was very weak; ENR removal process was based on the adsorption and biodegradation; CTC removal process was based to a large extent on the adsorption because of the big capacity of AnGS. These results were helpful to create a rational basis for designing more suitable treatment systems as feasible barriers to the release of antibiotics into the environment. HIGHLIGHTS The removal processes and mechanisms of common veterinary antibiotics in the high-rate anaerobic bioreactor were investigated.; Anaerobic granular sludge has an excellent chlortetracycline adsorption capacity.; Good enrofloxacin removal performance was ascribed to adsorption and biodegradation together.;

Keywords

• adsorption
• anaerobic granular sludge
• biodegradation
• high-rate anaerobic bioreactor
• veterinary antibiotics