Using a Two-Phase Hydrodynamic Model to Control Fouling in an Ultrafication Side-Stream MBR

A common problem encountered with membrane bioreactors (MBRs) systems is fouling of the membrane resulting in frequent cleaning and replacement which makes the system less appealing for full-scale applications. This hammers its commercialization due to reduction of productivity and increased maintenance and operational cost. Literature has shown that the hydrodynamics near the membrane surface have an impact on fouling. A two-phase hydrodynamic model was implemented in Fluent (Ansys, USA) using the Volume of Fluid (VOF) approach to simulate the slug flow inside the tubular membrane and to predict the shear rates near the wall. The model is used to determine optimal gas flow rate requirements in terms of pressure drop across the membrane tube. The effectiveness was evaluated through relating these inputs with apparent shear stresses near the membrane surface. The latter can be expressed as shear stress distributions (SSD). A range of gas-air flow rate mixtures were investigated and resulted in different SSDs.