Unveiling the role of upflow velocity and sludge recirculation on the fate of pharmaceuticals removal and microbial community change in the anaerobic baffled reactor - microaerobic biofilm- membrane bioreactor in treating building wastewater

This research studied the effects of upflow velocity (V up ) and sludge recirculation for operation of the novel anaerobic baffled reactor - microaerobic biofilm membrane bioreactor (ABR-MBMBR) system in treating Ciprofloxacin (CIP), Caffeine (CAF) and Sulfamethoxazole (SMX) contaminated in building wastewater. The upflow velocities of 3.5, 5.3 and 8.8 cm/h were obtained with the baffled compartments of 2,3 and 5, respectively. The ABR-MBMBR systems were operated with two sludge recirculation rates of 100% and 200%. The results show that increasing V up improved pharmaceutical removal, with optimal performance at 8.8 cm/h and 200% recirculation, achieving 70.3%, 92.8%, and 83.7% removal for CIP, CAF, and SMX, respectively, along with the highest membrane permeate flux and reduced fouling tendency. Enhanced performance was attributed to improved biomass substrate contact and the activity of key microbial consortia, including Aminicenantales for CIP degradation and Methanomethylovorans for SMX degradation. Overall, the ABR–MBMBR system demonstrates strong potential for efficient pharmaceutical removal and stable operation.