# US 12,005,396 B2 · Advancements in osmotically driven membrane systems including multi-stage purification > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,005,396 B2 - Document ID: US12005396B2 - Status: Granted - Kind: B2 - Application number: 16/684,406 - Filed: 2019-11-14 - Published: 2020-03-19 - Granted: 2024-06-11 - Earliest claimed: 2013-03-15 - Assignees: Porifera, Inc. - Applicants: Porifera, Inc. - Inventors: Charles Benton; Olgica Bakajin; Carl Lundin - Web page: https://patentgrep.com/patent/US12005396B2 ## CPC - B01D 61/58: Multistep processes - B01D 61/0022: {Apparatus therefor} - B01D 61/02: Reverse osmosis; Hyperfiltration {; Nanofiltration} - B01D 61/025: {Reverse osmosis; Hyperfiltration} - B01D 61/027: {Nanofiltration} - B01D 61/029: {Multistep processes comprising different kinds of membrane processes selected from reverse osmosis, hyperfiltration or nanofiltration} - B01D 61/06: Energy recovery - B01D 61/12: Controlling or regulating - B01D 65/02: Membrane cleaning or sterilisation {; Membrane regeneration} - C02F 1/441: {by reverse osmosis} - C02F 1/445: {by forward osmosis} - B01D 2311/14: Pressure control - B01D 2311/2521: to permeate side - B01D 2311/2523: to feed side - B01D 2313/243: Pumps - B01D 2313/246: Energy recovery means - B01D 2317/02: Elements in series - B01D 2317/025: Permeate series - B01D 2317/08: Use of membrane modules of different kinds - B01D 2321/167: Use of scale inhibitors - B01D 2325/20: Specific permeability or cut-off range - 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 An example water purification system for purifying high concentration feed solutions includes a high rejection forward osmosis module, one or more low rejection modules, and a high rejection reverse osmosis module. The low rejection modules may have different rejection levels. The system may be pressurized by one or more pumps. One or more of the low rejection modules may include one or more nanofiltration (NF) membranes. The draw solution may comprise a monovalent salt, a multivalent salt, or a combination of both. ## Claims ### Claim 1 A system, comprising: a system output; a plurality of low rejection stages connected in series, wherein a first low rejection stage of the plurality of low rejection stages is configured to receive a first stream from a draw side of a forward osmosis stage fluidly coupled thereto and provide a first output stream to the next low rejection stage in the plurality of low rejection stages, wherein the plurality of low rejection membrane stages include low rejection membrane modules having a low rejection membrane with a salt rejection rate of less than 90% at a first hydrostatic pressure, wherein the plurality of low rejection stages further comprises a final low rejection stage subsequent to the first low rejection stage, wherein the final low rejection stage is configured to provide a second output stream and a final reject stream, wherein the final reject stream is fluidly coupled to the first stream and provided to the draw side of the forward osmosis stage; a reverse osmosis stage configured to receive the second output stream from the final low rejection stage of the plurality of low rejection stages, wherein the reverse osmosis stage is further configured to provide a product stream and a reverse osmosis reject stream, wherein the reverse osmosis stage has a reverse osmosis membrane with a higher salt rejection than the low rejection membrane modules at the first hydrostatic pressure, wherein the product stream is provided to the system output as water; wherein the reverse osmosis reject stream is fluidly coupled to the first output stream directly prior to the final low rejection stage to recycle the reverse osmosis reject stream through the system, wherein at least a portion of the reverse osmosis reject stream is fluidly coupled with the first stream and provided to the draw side of the forward osmosis stage. ### Claim 2 (depends on 1) The system of claim 1, wherein the plurality of low rejection stages are configured to provide the final reject stream to a previous low rejection stage of the plurality of low rejection stages connected in series. ### Claim 3 (depends on 1) The system of claim 1, wherein a recovery rate of the plurality of low rejection stages is less than 90%. ### Claim 4 (depends on 1) The system of claim 1, wherein at least one of the plurality of low rejection stages has a salt rejection of less than 80% at the first hydrostatic pressure. ### Claim 5 (depends on 1) The system of claim 1, further comprising a pump configured to pressurize the first stream. ### Claim 6 (depends on 5) The system of claim 5, wherein the pump is configured to pressurize the first stream to a hydrostatic pressure of less than 3000 psi. ### Claim 7 (depends on 1) The system of claim 1, further comprising a pump configured to receive the second output stream from the final low rejection stage of the plurality of low rejection stages and pressurize the second output stream prior to the reverse osmosis stage. ### Claim 8 (depends on 1) The system of claim 1, further comprising an energy recovery device configured to receive a high pressure reject stream from one or more of the plurality of low rejection stages and to reduce the pressure of the high pressure reject stream. ### Claim 9 (depends on 1) The system of claim 1, wherein the portion of the reverse osmosis reject stream is operably coupled to the first stream prior to the plurality of low rejection membrane stages. ### Claim 10 (depends on 1) The system of claim 1, wherein the reverse osmosis stage is further configured to directly provide the product stream to the system output. ### Claim 11 A system, comprising: a first pump configured to pressurize a first stream; a plurality of low rejection stages connected in series, wherein a first low rejection stage of the plurality of low rejection stages is configured to receive the pressurized first stream from a draw side of a forward osmosis stage fluidly coupled thereto and provide a first output stream to the next low rejection stage in the plurality of low rejection stages, wherein the plurality of low rejection membrane stages include low rejection membrane modules having a low rejection membrane with a salt rejection rate of less than 90% at a first hydrostatic pressure, wherein the final low rejection stage is configured to provide a second output stream and a final reject stream, wherein the final reject stream is fluidly coupled to the pressurized first stream and provided to the draw side of the forward osmosis stage; a second pump configured to receive the second output stream from the final low rejection stage of the plurality of low rejection stages and pressurize the second output stream, wherein the final low rejection stage is subsequent to the first low rejection stage; a system output; and a reverse osmosis stage configured to receive the pressurized second output stream from the final low rejection stage, wherein the reverse osmosis stage is further configured to provide a product stream and a reverse osmosis reject stream, wherein the reverse osmosis stage has a reverse osmosis membrane with a higher salt rejection than the low rejection membrane modules at the first hydrostatic pressure, wherein the product stream is provided to the system output as water; wherein at least a portion of the reverse osmosis reject stream is fluidly coupled to the first stream directly prior to the final low rejection stage to recycle the reverse osmosis reject stream and provided to the draw side of the forward osmosis stage. ### Claim 12 (depends on 11) The system of claim 11, wherein the reverse osmosis stage is further configured to directly provide the product stream to the system output. ### Claim 13 (depends on 12) The system of claim 12, wherein the draw side includes a diluted draw stream output of the forward osmosis stage and the diluted draw stream output is fluidly coupled to the first low rejection stage of the plurality of low rejection stages. ### Claim 14 (depends on 12) The system of claim 12, further comprising an energy recovery device configured to receive a high pressure reject stream from one or more of the plurality of low rejection stages and to reduce the pressure of the high pressure reject stream.