Scouring method

• US 20040232076A1
• Filed: 06/14/2004
• Published: 11/25/2004
• Est. Priority Date: 12/20/1996
• Status: Abandoned Application

• Current Assignee: Clinton V. Kopp, Fufang Zha, Robert J. Mcmahon, Thomas W. Beck, Warren T. Johnson
• Original Assignee: Clinton V. Kopp, Fufang Zha, Robert J. Mcmahon, Thomas W. Beck, Warren T. Johnson
• Inventors: McMahon, Robert J., Zha, Fufang, Johnson, Warren T., Beck, Thomas W., Kopp, Clinton V.
• Application Number:
  US10/867,850
• Publication Number:
  US 20040232076A1
• Time in Patent Office: Days
• US Class Current: 210/636
• CPC Class Codes: B01D 2321/04 Backflushing
• CPC Class Codes: B01D 2321/185 Aeration
• CPC Class Codes: B01D 61/18 Apparatus therefor
• CPC Class Codes: B01D 63/0221 using a mould
• CPC Class Codes: B01D 63/0222 using centrifugal forces
• CPC Class Codes: B01D 63/0224 Opening the fibre ends after encapsulation
• CPC Class Codes: B01D 63/024 with a single potted end
• CPC Class Codes: B01D 63/16 Rotary, reciprocated or vibrated modules
• CPC Class Codes: B01D 65/02 Membrane cleaning or sterilisation ; Membrane regeneration

Abstract

The present invention relates to membrane filtration systems, and, in particular, arrangements where the membranes are supported within a tank or vessel containing the feed liquid to be filtered.

Claims

1. A method of aerating a membrane module immersed in a liquid substrate comprising the step of:

providing a flow of air to an aeration source below the membrane module, the flow of air alternating between a higher flow rate and a lower flow rate in repeated cycles of from greater than about 120 seconds to less than about 300 seconds in duration.

2. The method of claim 1, wherein the repeated cycles are from about 130 seconds to about 250 seconds in duration.

3. The method of claim 1, wherein the repeated cycles are from about 140 seconds to about 225 seconds in duration.

4. The method of claim 1, wherein the repeated cycles are from about 150 seconds to about 210 seconds in duration.

5. The method of claim 1, wherein the repeated cycles are from about 160 seconds to about 200 seconds in duration.

6. The method of claim 1, wherein the repeated cycles are from about 170 seconds to about 190 seconds in duration.

7. The method of claim 1, wherein the repeated cycles are about 180 seconds in duration.

8. The method of claim 1, wherein the flow of air produces transient flow conditions in the liquid substrate.

9. The method of claim 1, wherein the flow of air accelerates or decelerates the liquid substrate for much of the cycle so that the liquid substrate is rarely in a steady state.

10. The method of claim 1, wherein the aeration source comprises an aerator.

11. The method of claim 1, wherein the aeration source comprises perforated sheet.

12. The method of claim 1, wherein the aeration source comprises a jet.

13. The method of claim 1, wherein the aeration source is integral with the membrane module.

14. The method of claim 1, wherein the aeration source is separate from the membrane module.

15. The method of claim 1, wherein the lower flow rate is an air off condition.

16. The method of claim 1, wherein the lower flow rate is less than 25% of the higher flow rate.

17. The method of claim 1, wherein the lower flow rate is less than 40% of the higher flow rate.

18. The method of claim 1, wherein the lower flow rate is less than 50% of the higher flow rate.

19. The method of claim 1, wherein the lower flow rate is less than 75% of the higher flow rate.

20. The method of claim 1, wherein a plurality of membrane modules are aerated.

21. The method of claim 1, wherein the liquid substrate comprises water.

22. The method of claim 1, wherein the membrane module is immersed in a tank.

23. The method of claim 1, wherein the higher flow rate corresponds to a superficial velocity in relation to the aeration source receiving the flow of air of from about 0.005 m/s to about 0.5 m/s.

24. The method of claim 1, wherein the higher flow rate corresponds to a superficial velocity in relation to the aeration source receiving the flow of air of from about 0.010 m/s to about 0.2 m/s.

25. The method of claim 1, wherein the higher flow rate corresponds to a superficial velocity in relation to the aeration source receiving the flow of air of from about 0.015 m/s to about 0.15 m/s.