Enhancing microfiltration through an inorganic tubular membrane by gas sparging

A novel technique is tested for reducing tubular mineral membrane fouling b y injecting gas into a cross-flow stream. The injected gas is thought to fo rm complex hydrodynamic conditions inside the microfiltration module which increase the wall shear stress, preventing the membrane fouling and enhanci ng the microfiltration mass transfer. The experimental study was carried ou t with a ferric hydroxide suspension and a biologically treated wastewater, both of them filtered through a tubular inorganic membrane (Carbosep M14). The sparging led to an increase of the permeate flux with a slug flow stru cture for the two kinds of suspension. New dimensionless quantities of shea r stress number and resistance number were developed by generalized dimensi onal analysis of steady state flux in sparged and unsparged cross-flow filt ration. An unique formalism allowed interpretation of the experimental resu lts both in classical diphasic filtration and with gas sparging. The variat ion in the dimensionless numbers demonstrated the benefit of gas sparging. (C)2000 Elsevier Science B.V. All rights reserved.