Antibiotic removal from swine farming wastewater by anaerobic membrane bioreactor: Role of hydraulic retention time

This study investigated the impact of hydraulic retention time (HRT) on the removal of veterinary antibiotics by an anaerobic membrane bioreactor (AnMBR) for swine wastewater treatment. Ten commonly used antibiotics in the group of tetracyclines, fluoroquinolones, and sulfonamides were evaluated. Results show that a wide vari-ation from 21 to 99% was observed for antibiotic removal by AnMBR regardless of the applied HRT. The methane yield increased from 0.22 L/g COD to 0.28 L/g COD as the operational HRT was prolonged from 24 to 48 h for AnMBR. Doubling the HRT value enhanced removal of most antibiotics and methane yield by 2-30% and 22-47%, respectively. The enhanced antibiotic removal in response to HRT prolongation could be positively correlated to the enrichment of the genus unidentified_Synergistaceae. Moreover, prolonging HRT increased the relative abundance of the genera unidentified_Synergistaceae, Geobacter and Methanobrevibacter, which could strengthen hydrogenotrophic methanogenesis to enhance methane yield. In addition, HRT increase reduced the ratio of protein to polysaccharide in both extracellular polymeric substances and soluble microbial products, thereby, alleviating membrane fouling in AnMBR operation.