Fouling control in a submerged membrane reactor: Aeration vs membrane oscillations

Abstract

• Aeration and membrane oscillation as fouling mitigation strategies were compared. • Membrane oscillation is effective for mitigating membrane fouling due to particle deposition. • Predicted and experimental results matched reasonably well. • Model can predict the operating conditions for particle deposition on submerged membrane. • Membrane oscillation enhanced diclofenac removal by ∼ two times in a SPMR. Membrane fouling potential due to particle deposition in a submerged membrane reactor (SMR) was investigated using aeration and membrane oscillations. A mathematical model describing the particle dynamics and the magnitude of the forces acting on a particle/agglomerate near a membrane surface was developed. The simulation results were verified by conducting experiments with inert glass bead sizes (2.5–33.0 μm) at various aeration rates (1.0–4.0 LPM), oscillation intensity (frequency 0–11.34 Hz; amplitude 2–6 mm). Additionally, photocatalytic degradation of diclofenac (DCF) (initial concentration = 4 mg/L) using UV 365 nm and TiO 2 photocatalyst was used to characterize the system performance. The results indicate that membrane oscillation was significantly superior as a fouling mitigation strategy due to higher shear rates (up to 10 times) than that of aeration. In the studied operating parameter range, the simulation results indicate that in case of aeration, particles below ∼ 10 µm will be deposited on the membrane. Whereas, in case of membrane oscillation, a much smaller size of 0.1 µm below which particles will be deposited on membrane surface. This was further confirmed by the photocatalytic degradation of DCF using oscillatory membrane in a submerged photocatalytic membrane reactor (SPMR) where close to two times higher DCF degradation occurred using membrane oscillation with a negligible transmembrane pressure drop (TMP) of (0.1–3 kPA). The presented approach will be useful in predicting the membrane fouling due to deposition of polydisperse particles in submerged oscillatory membrane reactors.