Chemical Clean For Membrane Filter

• US 20080203017A1
• Filed: 04/28/2006
• Published: 08/28/2008
• Est. Priority Date: 04/29/2005
• Status: Active Grant

• Current Assignee: Evoqua Water Technologies LLC
• Original Assignee: Siemen Water Technologies Corporation (Siemens AG)
• Inventors: Zha, Fufang, Cao, Zhiyi
• Granted Patent: US 9,675,938 B2
• Time in Patent Office: Days
• US Class Current: 210/636
• CPC Class Codes: B01D 2321/04 Backflushing
• CPC Class Codes: B01D 2321/16 Use of chemical agents
• CPC Class Codes: B01D 61/22 Controlling or regulating
• CPC Class Codes: B01D 65/02 Membrane cleaning or sterilisation ; Membrane regeneration
• CPC Class Codes: C02F 1/444 by ultrafiltration or microfiltration
• CPC Class Codes: C02F 2303/16 Regeneration of sorbents, filters

Abstract

A method of cleaning a porous polymeric membrane having a feed side and a permeate side including the steps of introducing a fluid containing a cleaning agent to the permeate side of a membrane allowing the cleaning agent to contact the permeate side of the membrane for a predetermined time, and contact the pores of the membrane, or introducing a fluid containing a cleaning agent to the feed side of a membrane; applying a transmembrane pressure to force the fluid containing the cleaning agent from the feed side to the permeate side of the membrane; allowing the cleaning agent to contact the permeate side of the membrane for a predetermined time, and contact the pores of the membrane. Preferably a concentration gradient between the feed side fluid and the lumen side fluid containing the cleaning agent causes cleaning agent to diffuse into the feed side fluid. Pressure may be applied to the fluid containing a cleaning agent to dislodge, where present, dissolved and undissolved solid from the membrane pores. The pressure may be applied in a pulsed fashion, and can be by way of compressed air at a pressure not more than the membrane'"'"'s bubble point. The methods of the present invention may be preceded by, or followed with a backwash.

Claims

1. A method of cleaning a hollow fibre porous polymeric membrane having a feed side and a permeate side including comprising the steps of:

introducing a fluid containing a cleaning agent to the permeate side of a membrane; and

allowing the cleaning agent to contact the permeate side of the membrane under static pressure for a predetermined time and contact the pores of the membrane.

7. A method according to claim 1 further including the step of applying pressure to the fluid containing a cleaning agent on the permeate side to dislodge, where present, dissolved and undissolved solid from the membrane pores.

8. A method according to claim 7 wherein the pressure is applied in a pulsed fashion.

9. A method according to claim 7 wherein the membrane has a bubble point and pressure is by way of compressed air at a pressure not more than the membrane'"'"'s bubble point.

10. A method according to claim 1 preceded by a backwash.

11. A method according to claim 1 followed by a backwash prior to the recommencernent of filtration.

12. A method according to claim 1 repeated in cycles.

13. A method according to claim 1 wherein the porous polymeric membrane is part of a pressurized membrane filtration or immersed membrane filtration system.

14. A method according to claim 1 wherein the membrane is selected from a microfiltration, ultrafiltration or nanofiltration membrane.

15. A method according to claim 1 wherein the membrane is a capillary or flatsheet membrane.

16. A method according to claim 1 wherein the membranes are hollow fibre membranes, having a lumen side (permeate side) and a module or shell side (feed side).

17. A method according to claim 16 wherein a plurality of hollow fibre membranes are housed inside a module housing.

18. A method according to claim 17 wherein a plurality of the membranes is arranged in aligned bundles, creating a plurality of lumen spaces inside the hollow fibres and a contiguous space on the outer or shell side of the hollow fibres and wherein the lumens are arranged so that filtered fluid accumulates therein and is passed from the plurality of lumens into a combined filtration stream.

19. A method according to claim 1 wherein the fluid is water.

20. A method according to claim 18 wherein the fluid containing a cleaning agent is introduced to the lumens of these hollow fibre membranes.

21. A method according to claim 18 wherein the fluid containing a cleaning agent is introduced to the shell side of the membrane.

22. A method according to claim 21 wherein the fluid containing a cleaning agent is introduced to the shell side of the membrane by partially filling the shell side of the module 20 before being transported into the lumens.

23. A method according to claim 1 wherein the fluid containing the diffusible cleaning agent is retained in the membrane permeate side without applied pressure.

24. A method according to claim 1 wherein the fluid containing the diffusible cleaning agent is retained in the membrane permeate side with pressure approximately equal to the static head pressure.

25. A method according to claim 1 wherein the cleaning solution is any conventional cleaning solution.

2. A method of cleaning a hollow fibre porous polymeric membrane having a feed side and a permeate side comprising the steps of:

introducing a fluid containing a cleaning agent to the feed side of a membrane;

applying a transmembrane pressure to force the fluid containing the cleaning agent from the feed side to the permeate side of the membrane; and

allowing the cleaning agent to contact the permeate side of the membrane for a predetermined time and contact the pores of the membrane.

3. A method according to claim 2 wherein the transmembrane pressure is a small differential pressure.

4. A method of cleaning a hollow fibre porous polymeric membrane having a feed side and a permeate side including comprising the steps of:

providing a feed side fluid in contact with the feed side of the membrane;

introducing a fluid containing a cleaning agent to the permeate side of a membrane; and

allowing the cleaning agent to contact the permeate side of the membrane for a predetermined time to contact the pores of the membrane and diffuse into the feed side fluid.

5. A method according to claim 4 wherein a concentration gradient between the feed side fluid and the lumen side fluid containing the cleaning agent causes cleaning agent to diffuse into the feed side fluid.

6. A method according to claim 5 wherein the feed side fluid is lower in concentration of cleaning agent than the lumen side fluid.

26-33. -33. (canceled)