Gas/Liquid Two-phase Flow in a Flat Sheet Filtration Module: Measurement of Local Wall Shear Stresses

Air sparging in membrane filtration consists in generating an intermittent gas/liquid flow by injecting air in the concentrate compartment together with the feed. This process is very efficient for flux enhancement for different membrane processes. In order to understand the influence of wall shear stresses generated by the two-phase flow on the flux enhancement, this work aimed to characterize local wall shear stresses generated by the two-phase flow during filtration operated at a low permeate flux. Local wall shear stresses were measured using an electrochemical method in different points of a flat sheet nanofiltration module and for several operating conditions.