Effect of baffles number in the energy-saving anaerobic baffled reactor-sponge membrane bioreactor (EABR-SpMBR) on the enhancement of antibiotics removal from high-rise building wastewater

Abstract This research aims to conduct a comparative investigation of the role played by the number of baffle compartments and sludge recirculation rate in the energy-saving anaerobic baffled reactor-sponge membrane bioreactor (ABR-SpMBR) for enhancing antibiotics removal from high-rise building wastewater. The same volume of three ABR-SpMBR systems with 3, 4, and 6 compartments with micro-aeration and sludge recirculation were operated simultaneously to remove Ciprofloxacin (CIP), Caffeine (CAF), and Sulfamethoxazole (SMX) from real building wastewater at hydraulic retention time (HRT) of 48 hours. From the removal profile of the targeted antibiotics in the ABR-SpMBR, it was found that the ABR-SpMBR with the 6 compartments at the sludge recirculation rate of 200% has a significant removal efficiency of CIP (62.93%), CAF (94%), and SMX (92%), overall (more than 60%) than the other two ABRSpMBR. The removal mechanism indicates that recirculation sludge increases the biomass concentration, which helps maintain a stable microbial population and enhances the degradation efficiency of organic contaminants and targeted antibiotics within more compartments of the ABR-SpMBR system. Therefore, the ABR-SpMBR of 6 compartments with a sludge recirculation rate of 200% can be considered a promising technology for removing antibiotics when considering nutrient removal and an energy-saving approach with low aeration intensity. Additionally, the number of baffles influenced removal efficiency, with more compartments promoting extended contact time and improved degradation. These findings highlight the potential for optimizing sludge recirculation and reactor design in real-world wastewater treatment systems to enhance antibiotic removal and minimize environmental contamination.