A 80 m thick polysulphone microporous membrane has an average porosity of 0.4. Pure water flux through the membrane is 30 m/mh at a pressure drop of 1.5 bar at 25 C. The average pore size is estimated to be 3 um. Calculate the tortuosity factor of the pores, and water permeability of the membrane. The viscosity of water at 25 C is 0.85 cP. [5+2 M]