Enhanced performance of submerged membrane microfiltration by aeration and backwash for mitigating particle fouling

• Trans-membrane pressure and air flow rate positively affect filtration flux in submerged membrane microfiltration. • A 89.0% decrease in fouling resistance were observed as the bubble size decreased from 5.0 to 0.5 mm under aeration operation. • The tangential drag force acting on the membrane surface was proportional to ρ b d p 2 Q a / d b 2 • A 627% enhancement in filtration flux with the low energy consumption under operating conditions of t b = 5 s, t f = 1200 s, and q b = 4.5 × 10 -4 m 3 /m 2 s. Submerged membrane filtration (SMF) has been widely used for wastewater treatment and biochemical separation by integrating advanced filtration systems. However, membrane fouling is primarily caused by particle deposition on the membrane surface or blockage of membrane pores, leading to flux deterioration. While various hydrodynamic strategies have been developed to improve filtration performance, limited research establishes theoretical correlations between membrane fouling and filtration performance. Therefore, this study aims to investigate the effects of hydrodynamic conditions on flux and fouling resistance in submerged membrane microfiltration. The results showed that flux can be effectively enhanced by increasing trans-membrane pressure from 20 to 40 kPa and air flow rate or reducing bubble size. Force analysis revealed that the tangential drag force acting on the membrane surface was proportional to ρ b d p 2 Q a / d b 2 , and a correction to the hydrodynamic model was proposed and verified under various air flow rates from 1.7 × 10 -6 to 5.0 × 10 -6 m 3 /s. To further improve filtration, a self-cleaning backwash strategy was evaluated under various operating conditions. Among the experimental results, operation at t b = 5 s and t f = 1200 s with q b = 4.5 × 10 -4 m 3 /m 2 s achieved a 627% flux increase with low energy consumption, ensuring efficiency and sustainability. These findings provide valuable insights for developing more sustainable biochemical processes and industrial wastewater treatment.