# US 10,500,544 B2 · Advancements in osmotically driven membrane systems including multi-stage purification

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- Number: US 10,500,544 B2
- Document ID: US10500544B2
- Status: Granted
- Kind: B2
- Application number: 14/777,418
- Filed: 2014-03-14
- Published: 2016-01-07
- Granted: 2019-12-10
- Earliest claimed: 2013-03-15
- Assignees: Porifera, Inc.
- Applicants: Porifera, Inc.
- Inventors: Charles Benton; Olgica Bakajin; Carl Lundin
- Web page: https://patentgrep.com/patent/US10500544B2

## 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

An apparatus, comprising:
a forward osmosis module configured to receive a feed stream and a high concentration draw stream, wherein the forward osmosis module is further configured to produce a first stream comprising water from the feed stream and the high concentration draw stream via forward osmosis;
a pump configured to pressurize the first stream;
a low rejection membrane module configured to receive the pressurized first stream and to produce the high concentration draw stream and a low concentration stream via reverse osmosis, the low rejection membrane module having a low rejection membrane with a salt rejection rate of less than 90% at a first hydrostatic pressure; and
a reverse osmosis module configured to receive at least a portion of the low concentration stream and to produce a product stream and a reverse osmosis reject stream, wherein the reverse osmosis module has a reverse osmosis membrane with a higher salt rejection than the low rejection membrane module at the first hydrostatic pressure;
wherein the reverse osmosis reject stream is fluidly coupled to the high concentration draw stream prior to the forward osmosis module.

### Claim 2 (depends on 1)

The apparatus of claim 1, further comprising a second pump configured to pressurize the low concentration stream provided to the reverse osmosis module.

### Claim 3 (depends on 1)

The apparatus of claim 1, wherein the first stream is pressurized to less than 3000 psi.

### Claim 4 (depends on 1)

The apparatus of claim 1, further comprising an energy recovery device configured to reduce the pressure of the high concentration draw stream produced by the low rejection membrane module.

### Claim 5 (depends on 1)

The apparatus of claim 1, further comprising a feed pump configured to provide the feed stream to the forward osmosis module.

### Claim 6 (depends on 1)

The apparatus of claim 1, wherein the reverse osmosis reject stream is combined with the pressurized first stream provided to the low rejection membrane module prior to the low rejection membrane module.

### Claim 7 (depends on 1)

The apparatus of claim 1, wherein the low rejection membrane module has a salt rejection rate that is less than 80%.

### Claim 8 (depends on 1)

The apparatus of claim 1, wherein the low rejection membrane module comprises a membrane with a salt rejection rate that is less than 80%.

### Claim 9 (depends on 1)

The apparatus of claim 1, further comprising a dosing pump configured to provide a salt to the high concentration draw stream.

### Claim 10 (depends on 9)

The apparatus of claim 9, wherein the salt comprises a multivalent salt.

### Claim 11 (depends on 9)

The apparatus of claim 9, wherein the salt comprises a monovalent salt.

### Claim 12 (depends on 1)

The apparatus of claim 1, wherein the low concentration stream is provided to an additional low rejection membrane module configured to produce a dilute stream and a rejection stream, wherein the additional low rejection membrane module is disposed between the low rejection membrane module and the reverse osmosis module, and wherein the reverse osmosis module is configured to receive the dilute stream containing a portion of the low concentration stream.

### Claim 13 (depends on 12)

The apparatus of claim 12, wherein the reverse osmosis reject stream is combined with the pressurized first stream provided to the low rejection membrane module.

### Claim 14 (depends on 12)

The apparatus of claim 12, wherein the reverse osmosis reject stream is combined with the low concentration stream provided to the additional low rejection module.

### Claim 15 (depends on 12)

The apparatus of claim 12, further comprising a third pump configured to pressurize the dilute stream provided to the reverse osmosis module.

### Claim 16 (depends on 1)

The apparatus of claim 1, wherein the low rejection membrane module is configured to be operated at the first hydrostatic pressure and the reverse osmosis membrane module is configured to be operated at the first hydrostatic pressure.