# US 11,439,953 B2 · Brine concentration > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,439,953 B2 - Document ID: US11439953B2 - Status: Granted - Kind: B2 - Application number: 16/852,134 - Filed: 2020-04-17 - Published: 2020-10-08 - Granted: 2022-09-13 - Earliest claimed: 2015-02-02 - Assignees: Surrey Aquatechnology Limited - Applicants: Surrey Aquatechnology Limited - Inventors: Peter George Nicoll; Brian James Moore - Web page: https://patentgrep.com/patent/US11439953B2 ## CPC - B01D 61/029: {Multistep processes comprising different kinds of membrane processes selected from reverse osmosis, hyperfiltration or nanofiltration} - B01D 61/002: {Forward osmosis or direct osmosis} - B01D 61/025: {Reverse osmosis; Hyperfiltration} - B01D 61/027: {Nanofiltration} - B01D 61/58: Multistep processes - C02F 1/441: {by reverse osmosis} - C02F 1/442: {by nanofiltration} - C02F 1/445: {by forward osmosis} - B01D 2311/06: Specific process operations in the permeate stream - B01D 2311/08: Specific process operations in the concentrate stream - B01D 2311/12: Addition of chemical agents - B01D 2311/2523: to feed side - B01D 2317/025: Permeate series - C02F 1/04: by distillation or evaporation - C02F 2103/08: Seawater, e.g. for desalination - C02F 2301/046: Recirculation with an external loop - 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 A process for separating solvent from a feed solution, said process comprising: contacting a feed solution comprising solutes dissolved in a solvent with one side of a nanofiltration membrane, applying hydraulic pressure to the feed solution, such that solvent and some of the dissolved salts from the feed solution flow through the nanofiltration membrane to provide a permeate solution on the permeate-side of the nanofiltration membrane and a concentrated solution on the retentate-side of the nanofiltration membrane; contacting the permeate solution from the nanofiltration membrane with one side of a reverse osmosis membrane and applying hydraulic pressure to the permeate solution, such that solvent from the permeate solution flows through the reverse osmosis membrane to leave a concentrated solution on the retentate-side of the reverse osmosis membrane, using the concentrated solution from the retentate-side of the reverse osmosis membrane as at least part of the feed solution to the nanofiltration membrane; withdrawing at least a portion of the concentrated solution from the retentate-side of the nanofiltration membrane. ## Claims ### Claim 1 A process for separating solvent from a feed solution, said process comprising: contacting a feed solution comprising solutes dissolved in a solvent with one side of a nanofiltration membrane, applying hydraulic pressure to the feed solution, such that solvent and some of the dissolved salts from the feed solution flow through the nanofiltration membrane to provide a permeate solution on the permeate-side of the nanofiltration membrane and a concentrated solution on the retentate-side of the nanofiltration membrane; contacting the permeate solution from the nanofiltration membrane with one side of a reverse osmosis membrane and applying hydraulic pressure to the permeate solution, such that solvent from the permeate solution flows through the reverse osmosis membrane to leave a concentrated solution on the retentate-side of the reverse osmosis membrane, using the concentrated solution from the retentate-side of the reverse osmosis membrane as at least part of the feed solution to the nanofiltration membrane; withdrawing at least a portion of the concentrated solution from the retentate-side of the nanofiltration membrane; and wherein, prior to being used as at least a portion of the feed solution to the nanofiltration membrane, the concentrated solution from the retentate-side of the reverse osmosis membrane is passed through an additional semi-permeable membrane to provide a permeate solution on the permeate-side of the additional semi-permeable membrane and a retentate solution on the retentate-side of the additional semi-permeable membrane, which permeate solution is used as at least a portion of the feed to the nanofiltration membrane. ### Claim 2 (depends on 1) The process as claimed in claim 1, whereby, if the withdrawn portion of the concentrated solution from the retentate-side of the nanofiltration membrane is contacted with a further membrane, the further membrane has an average pore size or permeability that is no more than 100 times greater than the average pore size or permeability of the nanofiltration membrane. ### Claim 3 (depends on 1) The process as claimed in claim 1, wherein the withdrawn portion of the concentrated solution from the retentate-side of the nanofiltration membrane is i) disposed of; ii) further concentrated prior to disposal; or iii) contacted with one side of a direct osmosis membrane to draw water from source water on the opposite side of the direct osmosis membrane by direct osmosis. ### Claim 4 (depends on 3) The process as claimed in claim 3, wherein the withdrawn portion of concentrated solution from the retentate-side of the nanofiltration membrane is concentrated using a membrane, thermal evaporator or crystalliser. ### Claim 5 (depends on 1) The process as claimed in claim 1, wherein the nanofiltration membrane is selected such that sufficient dissolved solute passes through the nanofiltration membrane, whereby the osmotic pressure of the permeate solution on the permeate-side of the nanofiltration membrane is at least 50% of the osmotic pressure of the feed solution. ### Claim 6 (depends on 1) The process as claimed in claim 1, wherein the concentrated solution from the retentate-side of the reverse osmosis membrane is combined with a further salt solution and the combined stream used as the feed solution to the nanofiltration membrane. ### Claim 7 (depends on 1) The process as claimed in claim 1, wherein the permeate solution from the nanofiltration membrane is combined with a further salt solution and the combined stream contacted with one side of the reverse osmosis membrane. ### Claim 8 (depends on 3) The process as claimed in claim 3, wherein the withdrawn portion of the concentrated solution from the retentate-side of the nanofiltration membrane is concentrated by contacting said withdrawn portion with one side of a further semi-permeable membrane, and applying hydraulic pressure to said withdrawn portion, such that solvent from said portion flows through the further semi-permeable membrane to provide a permeate solution on the permeate-side of the further semi-permeable membrane and a retentate solution on the retentate-side of the further semi-permeable membrane, wherein the retentate solution on the retentate-side of the further semi-permeable membrane is withdrawn and disposed of or concentrated further prior to disposal. ### Claim 9 (depends on 8) The process as claimed in claim 8, wherein the permeate solution from permeate-side of the further semi-permeable membrane is combined with the concentrated solution from the retentate-side of the reverse osmosis membrane and introduced into the nanofiltration membrane. ### Claim 10 (depends on 8) The process as claimed in claim 8, wherein the further semi-permeable membrane is a nanofiltration membrane. ### Claim 11 (depends on 1) The process as claimed in claim 1, wherein the retentate solution on the retentate-side of the additional semi-permeable membrane is withdrawn and disposed of or further concentrated. ### Claim 12 (depends on 1) The process as claimed in claim 1, wherein the withdrawn portion of concentrated solution on the retentate-side of the nanofiltration membrane is concentrated by passing said withdrawn portion through the additional or another semi-permeable membrane and applying hydraulic pressure to said withdrawn portion such that solvent from said portion flows through the membrane to provide a permeate solution on the permeate-side of the semi-permeable membrane and a retentate solution on the retentate-side of the membrane, which retentate is withdrawn and disposed of or concentrated further prior to disposal. ### Claim 13 (depends on 12) A process as claimed in claim 12, wherein the withdrawn portion of concentrated solution on the retentate-side of the nanofiltration membrane is combined with the concentrated solution from the retentate-side of the reverse osmosis membrane and the combined stream is passed through the additional semi-permeable membrane. ### Claim 14 (depends on 1) A process as claimed in claim 1, wherein the additional semi-permeable membrane is a nanofiltration membrane. ### Claim 15 (depends on 1) The process as claimed in claim 1, wherein the solution that permeates the reverse osmosis membrane is withdrawn as product water. ### Claim 16 (depends on 1) The process as claimed in claim 1, wherein, when withdrawn, the withdrawn portion of concentrated solution from the retentate-side of the nanofiltration membrane has a total dissolved salts concentration of at least 90,000 mg/l. ### Claim 17 (depends on 1) The process as claimed in claim 1, wherein the feed solution has an initial concentration of multivalent cations and multivalent anions that is greater than the concentration of monovalent cations and monovalent anions, and wherein the process further comprises the step of adding monovalent cation and/or monovalent anion to the feed solution before the feed solution is contacted with the nanofiltration membrane. ### Claim 18 (depends on 17) The process as claimed in claim 17, wherein the monovalent cation and/or monovalent anion is added to the feed solution to raise the osmotic pressure of the permeate solution on the permeate-side of the nanofiltration membrane to at least 50% of the osmotic pressure of the feed solution. ### Claim 19 (depends on 17) The process as claimed in claim 17, wherein the withdrawn portion of the concentrated solution from the retentate-side of the nanofiltration membrane is concentrated by contacting said withdrawn portion with one side of a further nanofiltration membrane, and applying hydraulic pressure to said withdrawn portion, such that solvent from said portion flows through the further nanofiltration membrane to provide a permeate solution on the permeate-side of the further nanofiltration membrane and a retentate solution on the retentate-side of the further nanofiltration membrane, wherein the retentate solution on the retentate-side of the further nanofiltration membrane is withdrawn and disposed of or concentrated further prior to disposal. ### Claim 20 (depends on 19) The process as claimed in claim 19, wherein, prior to contact with the further nanofiltration membrane, monovalent cation and/or monovalent anion are added to the withdrawn portion.