# US 7,608,188 B2 · Vacuum enhanced direct contact membrane distillation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,608,188 B2 - Document ID: US7608188B2 - Status: Granted - Kind: B2 - Application number: 11/293,407 - Filed: 2005-12-02 - Published: 2006-07-06 - Granted: 2009-10-27 - Earliest claimed: 2004-12-03 - Assignees: Board of Regents of the Nevada System of Higher Education - Inventors: Tzahi Y. Cath; V. Dean Adams; Amy E. Childress - Web page: https://patentgrep.com/patent/US7608188B2 ## CPC - B01D 61/364: {Membrane distillation} - C02F 1/447: {by membrane distillation (distillation and evaporation without the use of membranes C02F1/04)} - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes) ## Abstract The present disclosure provides methods and systems for purifying an impaired liquid. In a particular example, the disclosure provides methods and systems for purifying water containing a solute. A feed stream of solute containing water is introduced in a flow chamber. A permeate stream of water at least substantially free of the solute is placed in the flow chamber. A hydrophobic membrane is placed between the feed stream and the permeate stream. A vacuum is applied to the permeate stream. A vapor pressure differential causes water to vaporize from the feed stream, pass through the hydrophobic membrane, and condense in the permeate stream. ## Claims ### Claim 1 A liquid extraction system comprising: a feed source configured to supply a feed stream having a first pressure and comprising a solvent; a permeate source comprising an inlet and a fluid at a second pressure and configured to supply a permeate stream; a flow cell comprising a feed inlet, a feed outlet, a permeate inlet, a permeate outlet, and a membrane, the flow cell coupled to the feed source and the permeate source such that the membrane is intermediate, and may be placed in contact with, the feed and permeate streams; a flow pump in communication with the feed source, whereby the flow pump causes the feed stream to flow on the membrane; a vacuum pump operatively coupled to the permeate outlet of the flow cell and to the inlet of the permeate source, whereby the vacuum pump draws a vacuum on the permeate stream and the permeate side of the flow cell, causing permeate to flow from the permeate source, though the permeate inlet of the flow cell into the flow cell, and from the permeate outlet of the flow cell back into the permeate source; whereby a partial vapor pressure differential is induced across the membrane by a temperature differential between the feed and permeate streams and a differential between the first and second pressures, causing solvent to evaporate from the feed stream, pass through the membrane, and condense in the permeate stream flowing through the flow cell. ### Claim 2 (depends on 1) The system of claim 1, wherein the temperature of the feed stream is higher than the temperature of the permeate stream. ### Claim 3 (depends on 1) The system of claim 1, wherein a solute is dissolved in the feed stream. ### Claim 4 (depends on 3) The system of claim 3, wherein the solute comprises sodium chloride. ### Claim 5 (depends on 3) The system of claim 3, wherein the solute comprises sea salt. ### Claim 6 (depends on 1) The system of claim 1, wherein the feed stream is selected from the group consisting of treated wastewater, liquid foods, biological substances, runoff water, and seawater. ### Claim 7 (depends on 1) The system of claim 1, wherein the permeate stream is selected from the group consisting of distilled deionized water, potable water, and water having relatively low total dissolved solids. ### Claim 8 (depends on 1) The system of claim 1, wherein the permeate stream and the feed stream each have a flow velocity and the flow velocity of the permeate stream is at least approximately equal to the flow velocity of the feed stream. ### Claim 9 (depends on 1) The system of claim 1, wherein the feed stream runs countercurrent to the permeate stream. ### Claim 10 (depends on 1) The system of claim 1, wherein the membrane is microporous. ### Claim 11 (depends on 1) The system of claim 1, wherein the membrane is hydrophobic. ### Claim 12 (depends on 11) The system of claim 11, wherein the hydrophobic membrane is a composite membrane comprising a polytetrafluoroethylene active layer and a polypropylene support sublayer. ### Claim 13 (depends on 11) The system of claim 11, wherein the hydrophobic membrane is a symmetric, isotropic membrane made from pure polypropylene. ### Claim 14 (depends on 1) The system of claim 1, wherein the flow pump causes the pressure in the feed stream to be lower than atmospheric pressure. ### Claim 15 An extraction system comprising: (A) a feed cycle configured to supply a feed stream comprising a solvent at a first temperature and a first pressure, the feed cycle comprising (i) a feed source; (ii) a feed cycle flow pump in communication with the feed source; (iii) a feed stream temperature gauge, wherein the feed stream temperature gauge may be placed in communication with the feed stream; (iv) a feed stream flow meter, wherein the feed stream flow meter may be placed in communication with the feed stream; (B) a permeate cycle configured to supply a permeate stream at a second temperature and a second pressure, the second temperature being lower than the first temperature, the permeate cycle comprising: (i) a permeate source comprising an inlet and an outlet; (ii) a permeate cycle vacuum pump comprising an inlet and an outlet, the permeate cycle vacuum pump outlet operatively coupled to the inlet of the permeate source, the permeate cycle vacuum pump configured to draw a vacuum on the permeate stream, causing the second pressure to be lower than the first pressure; (iii) a permeate stream temperature gauge, wherein the permeate stream temperature gauge may be placed in communication with the permeate stream; (iv) a permeate stream flow meter, wherein the permeate stream flow meter may be placed in communication with the permeate stream; (v) a permeate stream pressure gauge; and (C) a flow cell, the flow cell comprising: (i) a permeate side comprising a permeate inlet and a permeate outlet, the permeate outlet in fluid communication with the inlet of the permeate cycle vacuum pump, the permeate inlet operatively coupled to the outlet of the permeate source and configured to transmit the permeate stream into the permeate side of the flow cell; (ii) a feed side comprising a feed inlet, the feed inlet in fluid communication with the feed source and configured to transmit the feed stream into the feed side of the flow cell; (iii) a membrane interposed between the permeate side and the feed side and configured to be contacted with the feed stream and the permeate stream; whereby a partial pressure differential is induced across the membrane by the differentials between the first and second temperatures and the first and second pressures, causing solvent to evaporate from the feed stream, pass through the membrane, and condense in the permeate stream. ### Claim 16 (depends on 15) The extraction system of claim 15, wherein the feed cycle pump is configured to place the feed stream under vacuum. ### Claim 17 (depends on 15) The extraction system of claim 15, the flow cell further comprising a gasket, the gasket abutting the membrane. ### Claim 18 (depends on 15) The extraction system of claim 15, wherein the membrane is one of a plurality of membranes, further comprising a plurality of gaskets, each of the plurality of gaskets abutting a membrane and forming a stack having a plurality of alternating layers of membranes and gaskets. ### Claim 19 (depends on 18) The extraction system of claim 18, wherein a first portion of the plurality of gaskets are in communication with the feed stream and a second portion of the plurality of gaskets are in communication with the permeate stream, each of the plurality of membranes abutted by a gasket in communication with the permeate stream and a gasket in communication with the feed stream. ### Claim 20 (depends on 15) The extraction system of claim 15, wherein the flow cell comprises a pressure vessel and the membrane is rolled inside the pressure vessel, forming a plurality of membrane layers, each layer being abutted on a first side by the feed stream and being abutted on a second side by the permeate stream. ### Claim 21 (depends on 1) The extraction system of claim 1 wherein the feed stream comprises impaired water. ### Claim 22 (depends on 15) The extraction system of claim 15 wherein the feed stream comprises impaired water. ### Claim 23 An extraction apparatus comprising: (A) a flow cell comprising: (i) a permeate side comprising a permeate inlet and a permeate outlet; (ii) a feed side comprising a feed inlet; (iii) a membrane distillation membrane interposed between the permeate side and the feed side; (B) a flow pump coupled to the feed side of the flow cell; (C) a permeate source; and (D) a vacuum pump having an inlet coupled to the permeate outlet and an outlet coupled to the permeate source.