# US 10,441,921 B2 · Maintenance of gas layers for fouling prevention on submerged surfaces > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,441,921 B2 - Document ID: US10441921B2 - Status: Granted - Kind: B2 - Application number: 15/157,663 - Filed: 2016-05-18 - Published: 2016-11-24 - Granted: 2019-10-15 - Earliest claimed: 2015-05-18 - Assignees: Massachusetts Institute of Technology - Applicants: Massachusetts Institute of Technology - Inventors: David Elan Martin Warsinger; Jaichander Swaminathan; John H. Lienhard; Amelia Tepper Servi - Web page: https://patentgrep.com/patent/US10441921B2 ## CPC - B01D 65/02: Membrane cleaning or sterilisation {; Membrane regeneration} - B01D 61/364: {Membrane distillation} - B01D 65/08: Prevention of membrane fouling or of concentration polarisation - B01D 67/0037: {by deposition from the gaseous phase, e.g. CVD, PVD} - B01D 67/0088: {Physical treatment with compounds, e.g. swelling, coating or impregnation} - B01D 71/32: containing fluorine atoms - B01D 53/228: {characterised by specific membranes} - B01D 2311/243: Electrical conductivity control - B01D 2321/04: Backflushing - B01D 2321/18: Use of gases - B01D 2325/06: Surface irregularities - B01D 2325/38: Hydrophobic membranes - 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) ## Abstract An apparatus for enhanced anti-fouling of a submerged surface includes a bath of a feed liquid that includes water; a fouling structure in contact with the feed liquid; and a gas feed configured to introduce a gas into contact with the fouling structure and the feed liquid to separate the fouling structure from the feed liquid with a gas layer. ## Claims ### Claim 1 An apparatus for enhanced anti-fouling of a submerged surface, the apparatus comprising: a bath of a feed liquid including water; a fouling structure in contact with the feed liquid, wherein the fouling structure has a surface with a rugosity greater than 3 in contact with the feed liquid; a mesh configured and positioned to trap gas bubbles at the surface of the fouling structure, wherein the mesh has a spacing of 2-5 mm between mesh elements; and a gas feed configured to introduce a gas into contact with the fouling structure and the feed liquid to separate the fouling structure from the feed liquid with a gas layer that is, at least in part, trapped between the mesh and the fouling structure. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the fouling structure is a porous membrane. ### Claim 3 (depends on 2) The apparatus of claim 2, wherein the porous membrane is polymeric. ### Claim 4 (depends on 2) The apparatus of claim 2, wherein the porous membrane has a superhydrophobic surface in contact with the feed liquid or gas layer. ### Claim 5 (depends on 2) The apparatus of claim 2, wherein the porous membrane comprises a polymer selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and polypropylene (PP). ### Claim 6 (depends on 5) The apparatus of claim 5, wherein the porous membrane further comprises a fluoropolymer coating on the polymer. ### Claim 7 (depends on 6) The apparatus of claim 6, wherein the fluoropolymer is selected from at least one of the following: poly-(1H,1H,2H,2H-perfluorodecyl acrylate (PPFDA); a C6 analog of PFDA; and polytetrafluoroethylene. ### Claim 8 (depends on 1) The apparatus of claim 1, wherein the feed liquid is a saline solution. ### Claim 9 (depends on 8) The apparatus of claim 8, wherein the feed liquid includes at least one of the following: NaCl, CaSO4, silica, alginate, CaCO3, MgOH, bacteria, algae, humic acid, and biological molecules. ### Claim 10 (depends on 1) The apparatus of claim 1, wherein the fouling structure includes a surface coating on an underlying structure, wherein the surface coating is in contact with the feed liquid and is more hydrophobic than the underlying structure. ### Claim 11 A method for reducing fouling of membrane surfaces, comprising: contacting a surface of a porous membrane with a bath of feed liquid; introducing a gas into contact with the surface of the porous membrane in contact with the feed liquid; monitoring for performance decay in removing water vapor from the feed liquid through the porous membrane; and intermittently injecting the gas when a decline in performance is detected. ### Claim 12 (depends on 11) The method of claim 11, wherein the fouling structure is a porous membrane. ### Claim 13 (depends on 12) The method of claim 12, wherein the gas is injected into contact with the surface of the porous membrane. ### Claim 14 (depends on 13) The method of claim 13, wherein the gas is injected into the feed liquid. ### Claim 15 (depends on 12) The method of claim 12, wherein the gas is injected with sufficient pressure to push the feed liquid out of pores in the porous membrane as the gas is forced through the porous membrane. ### Claim 16 (depends on 11) The method of claim 11, where the decline in performance is detected by at least one of the following: a measurement of electrical conductivity through the feed liquid; a mass flow rate measurement in the apparatus; and a temperature reading in the apparatus. ### Claim 17 (depends on 11) The method of claim 11, wherein the gas is selected from at least one of the group including air, water vapor, nitrogen, CO2, and oxygen. ### Claim 18 (depends on 11) The method of claim 11, wherein the method is performed in an application selected from the following: water purification; a heat exchanger; oil or gas separation; biological processes; medical procedures; filters; clothing; and gasification processes. ### Claim 19 (depends on 11) The method of claim 11, wherein the gas is introduced from a source selected from a pressurized gas tank, a gas pump, and a piston. ### Claim 20 (depends on 11) The method of claim 11, wherein gas feed is continuously bubbled through the feed liquid. ### Claim 21 (depends on 12) The method of claim 12, wherein the gas is injected on an opposite side of the porous membrane from the feed liquid at a pressure greater than a liquid entry pressure of the feed liquid into the membrane, wherein the gas enters pores in the membrane and pushes the feed liquid out of the pores in the porous membrane. ### Claim 22 A method for reducing fouling of membrane surfaces, comprising: contacting a surface of a porous membrane with a bath of feed liquid; introducing a gas into contact with the surface of the porous membrane in contact with the feed liquid; and using a mesh to trap bubbles of the gas at the surface of the membrane, wherein the mesh has a spacing of 2-5 mm between mesh elements.