How slug flow can enhance the ultrafiltration flux in mineral tubular membranes

The study deals with the use of a gas-liquid two-phase flow to reduce tubular mineral membrane fouling by injecting air directly into the feed stream. The injected air is supposed to create complex hydrodynamic conditions inside the ultrafiltration module which destabilize the concentration layer over the membrane surface. The experimental study was carried out by filtering suspensions (bentonite and yeast) through an ultrafiltration tubular mineral membrane. A range of transmembrane pressures and various liquid and gas flow-rates were tested. Results related to the permeate flux showed an enhancement by a factor of 3, with a slug flow-structure for the two kinds of suspension (200% of flux increase). Furthermore, the applicability of such an unsteady technique was examined with a view to reduce energy consumption.