Shear profiles inside gas sparged submerged hollow fiber membrane modules

Gas sparging is a common strategy used to minimize and prevent fouling on membrane surfaces. Although there have been numerous studies on the hydrodynamic conditions and the mechanisms of fouling control in confined membrane systems such as tubular membranes, there is very limited literature available that describes the hydrodynamic conditions and mechanisms of fouling control in unconfined systems such as submerged hollow fiber membranes. The present study investigated bubble-induced shear profiles in submerged hollow fiber membrane modules using an electrochemical method for measuring shear forces. The effects of different operating conditions such as gas sparging rates, fiber packing densities, diffuser nozzle sizes, and module configurations (i.e. loosely versus tightly held) on shear profiles were studied. It was found that the hydrodynamic conditions in confined tubular membrane systems and unconfined submerged hollow fiber membranes are different, which implies that the mechanisms of fouling control in submerged hollow fiber membrane units may be different than those in confined systems such as the tubular membranes.