OSMOTIC SEPARATION SYSTEMS AND METHODS

• US 20120267307A1
• Filed: 04/24/2012
• Published: 10/25/2012
• Est. Priority Date: 04/25/2011
• Status: Active Grant

• Current Assignee: China CAMC Engineering Hongkong Company Limited
• Original Assignee: Oasys Water, Inc.
• Inventors: McGinnis, Robert L.
• Granted Patent: US 9,039,899 B2
• Time in Patent Office: Days
• US Class Current: 210/638
• CPC Class Codes: B01D 2311/08 Specific process operations in the concentrate stream
• CPC Class Codes: B01D 2311/2669 Distillation
• CPC Class Codes: B01D 2311/2673 Evaporation
• CPC Class Codes: B01D 2311/2688 Biological processes
• CPC Class Codes: B01D 2321/185 Aeration
• CPC Class Codes: B01D 61/00 Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor separation of gases or vapours by diffusion B01D53/22
• CPC Class Codes: B01D 61/002 Forward osmosis or direct osmosis
• CPC Class Codes: B01D 61/025 Reverse osmosis; Hyperfiltration
• CPC Class Codes: B01D 61/08 Apparatus therefor
• CPC Class Codes: B01D 61/58 Multistep processes
• CPC Class Codes: B01D 65/08 Prevention of membrane fouling or of concentration polarisation
• CPC Class Codes: C02F 1/04 by distillation or evaporation
• CPC Class Codes: C02F 1/441 by reverse osmosis
• CPC Class Codes: C02F 1/445 by forward osmosis
• CPC Class Codes: C02F 2103/08 Seawater, e.g. for desalination
• CPC Class Codes: Y02A 20/131 Reverse-osmosis
• CPC Class Codes: Y02W 10/37 using solar energy

Abstract

Separation processes using osmotically driven membrane systems are disclosed generally involving the extraction of solvent from a first solution to concentrate solute by using a second concentrated solution to draw the solvent from the first solution across a semi-permeable membrane. Enhanced efficiency may result from using low grade waste heat from industrial or commercial sources. Pre-treatment and post-treatment may also enhance the osmotically driven membrane processes.

Claims

1. A method of maximizing draw solute recovery in an osmotically driven membrane system, the method comprising the steps of:

providing a first osmotically driven membrane system comprising a forward osmosis membrane and configured for receiving a first solution on a first side of the membrane and a concentrated draw solution on a second side of the membrane;

osmotically separating a solvent from the first solution using the concentrated draw solution, thereby forming a second solution on the first side of the membrane and a dilute draw solution on the second side of the membrane, wherein the second solution comprises at least one first ionic species of solute via reverse ion exchange through the membrane;

separating the dilute draw solution to recover at least one draw solute and the solvent, wherein the recovered solvent comprises at least one second ionic species of solute;

recycling the recovered at least one draw solute to the first osmotically driven membrane system;

providing a second osmotically driven membrane system comprising a reverse osmosis membrane;

pressurizing the recovered solvent in the second osmotically driven membrane system to recover a substantially pure solvent and a concentrated solution comprising the at least one second ionic species of solute;

recycling the concentrated solution comprising the at least one second ionic species of solute to the first osmotically driven membrane system, wherein the concentrated solution is added to the first solution, thereby resulting in the second solution comprising the at least one first ionic species of solute and the at least one second ionic species of solute;

balancing the at least one first species of solute with the at least one second species of solute to form additional removable draw solutes; and

separating the second solution to recover the additional draw solutes and a third solution.

2. The method of claim 1 further comprising the step of recycling the additional draw solutes into the concentrated draw solution.

3. The method of claim 1, wherein the step of separating the dilute draw solution comprises distillation.

4. The method of claim 1, wherein the concentrated draw solution comprises ammonia and carbon dioxide in a molar ratio of at least 1:

1.

5. A system for osmotic extraction of a solvent from a first solution, comprising:

a forward osmosis system comprising;

a first chamber having an inlet fluidly connected to a source of the first solution;

a second chamber having an inlet fluidly connected to a source of a concentrated draw solution; and

a semi-permeable membrane system separating the first chamber from the second chamber;

a first separation system fluidly coupled to the forward osmosis system downstream of the second chamber and configured to receive a dilute draw solution therefrom and to separate the dilute draw solution into draw solutes and a solvent stream;

a pressure exchanger fluidly coupled to the separation system and configured to pressurize and transport the solvent stream;

a reverse osmosis system fluidly coupled to the pressure exchanger and comprising;

a first chamber configured for receiving the pressurized solvent stream;

a semi-permeable membrane coupled to the first chamber; and

a second chamber coupled to the semi-permeable membrane and configured for receiving a solvent fluxed through the membrane, wherein the first chamber of the reverse osmosis unit is fluidly coupled to the first chamber of the forward osmosis unit to provide at least a portion of the first solution; and

a second separation system fluidly coupled to the first chamber of the forward osmosis system and configured for receiving a concentrated first solution therefrom and removing at least one of draw solutes and a product stream from the concentrated first solution.

6. The system of claim 5 further comprising a recycling system in fluid communication with the second separation system for returning the separated draw solutes to the concentrated draw solution.

7. The system of claim 5, wherein the concentrated draw solution comprises ammonia and carbon dioxide in a molar ratio of at least one to one.

8. The system of claim 5, wherein at least one of the first and second separation systems comprises at least one of a distillation column or a contact membrane.

9-16. -16. (canceled)

17. A system for the processing of a solution using osmosis, the system comprising:

a forward osmosis module comprising;

a first chamber in fluid communication with a source of a first solution comprising a solvent and at least one solute;

a second chamber in fluid communication with a concentrated draw solution; and

a semi-permeable membrane coupling the first chamber and the second chamber; and

means for introducing a plurality of seeds into the first chamber, wherein the plurality of seeds cause nucleation of at least a portion of the at least one solute when the first solution is introduced into the first chamber.

18. The system of claim 17 further comprising a separation module in fluid communication with the second chamber for recovering at least one of a solvent stream and draw solutes.

19. The system of claim 18 further comprising means for recycling draw solutes into the concentrated draw solution.

20. The system of claim 17 further comprising a recovery module in fluid communication with the first chamber for recovering precipitated solutes.

21. (canceled)