Patent ID: 8147699

Claim:
A method for separating a liquid feedstock in a membrane apparatus into a permeate and gas-containing retentate which method comprises: (a) providing a membrane device for receiving a liquid feedstock and a gas and for separating the feedstock into a permeate and a gas-containing retenetate, the membrane device comprising: at least one monolith of porous material, the monolith containing a plurality of feedstock passageways extending longitudinally from a feed end face to a retentate end face of the monolith and defining passageway hydraulic diameters, through which the liquid feedstock and gas flow to pass the gas-containing retentate from the device; the porous material of the monolith having a porosity of at least 30% and a mean pore size of at least 3 microns; a permselective membrane of a pore size smaller than that of the porous material, the permselective applied to the feedstock passageway wall surfaces of the monolith, the permselective membrane selected from the group consisting of membranes suitable for microfiltration, ultrafiltration, nanofiltration, reverse osmosis or pervaporation; at least one permeate conduit within the device, the permeate conduit isolated from the feed and retentate end faces, for carrying permeate toward a permeate collection zone external to the device, the permeate conduit providing a path of lower flow resistance than that of alternative flow paths through the porous material; at least one inlet to the device for introduction of the feedstock and the gas to the feed end face of the device; at least one outlet from the device for withdrawal of the gas-containing retentate from the retentate end face of the device; and at least one seal to separate the feedstock and the gas-containing retentate from the permeate collection zone; (b) introducing a liquid feedstock and a gas into the feed end face of the device, the gas comprising relatively coarse bubbles, at least some of which are larger than the monolith passageway hydraulic diameters; (c) using the feed end face of the device to break up the larger bubbles into smaller bubbles that enter the feedstock passageways along with the liquid feedstock in a gas-liquid flow constrained within the feedstock passageways for separation into filtrate and gas-containing retentate; (d) flowing at least a portion of the permeate through the permeate conduit toward the external permeate collection zone; (e) collecting the permeate in the permeate collection zone and removing the permeate from the device; and (f) removing the gas-containing retentate from the retentate end face of the device.