Enhancing the efficiency of air bubbles using a finned panel spacer for membrane fouling control in activated sludge filtration

• A finned spacer was explored to control membrane fouling in membrane bioreactors. • The spacer directed the air bubbles toward the membrane surface to scour off the foulant. • The spacer also promoted liquid circulation beneficial for membrane fouling control. • Intermittent aeration offered energy-saving without reducing the throughput. Membrane fouling remains a critical challenge in membrane bioreactors (MBRs). The main objective of this study was to systematically investigate a newly developed finned spacer that direct air bubbles to enhance foulant scouring. Lab-scale tests and computational fluid dynamics (CFD) simulations revealed that the spacer enhanced permeability by 30 % (from 289.2 ± 2.1 to 396.3 ± 9.3 L m⁻² h⁻¹ bar⁻¹). This improvement was attributed to enhanced bubble-membrane contact and liquid recirculation, enabling effective cleaning at relatively low aeration (0.25 L min⁻¹) and thus reducing energy demands. While smaller fin gaps optimized the bubble trajectory, it also slightly increased drag forces. Intermittent aeration further halved the energy use. Overall, the finned represents a cost-effective and energy-efficient strategy for mitigating membrane fouling in MBRs.