Scouring method

• US 20030178365A1
• Filed: 02/18/2003
• Published: 09/25/2003
• Est. Priority Date: 12/20/1996
• Status: Abandoned Application

• Current Assignee: US Filter Wastewater Group Incorporated (Siemens AG)
• Original Assignee: US Filter Wastewater Group Incorporated (Siemens AG)
• Inventors: McMahon, Robert J., Zha, Fufang, Johnson, Warren T., Beck, Thomas W., Kopp, Clinton V.
• Application Number:
  US10/369,813
• Publication Number:
  US 20030178365A1
• Time in Patent Office: Days
• US Class Current: 210/636
• CPC Class Codes: B01D 2315/06 Submerged-type; Immersion type
• CPC Class Codes: B01D 2321/04 Backflushing
• CPC Class Codes: B01D 2321/16 Use of chemical agents
• CPC Class Codes: B01D 2321/168 Use of other chemical agents
• CPC Class Codes: B01D 2321/185 Aeration
• CPC Class Codes: B01D 2321/2058 by vibration of the membrane, e.g. with an actuator
• CPC Class Codes: B01D 61/18 Apparatus therefor
• CPC Class Codes: B01D 63/022 Encapsulating hollow fibres
• CPC Class Codes: B01D 63/0221 using a mould
• CPC Class Codes: B01D 63/024 with a single potted end
• CPC Class Codes: B01D 63/0241 being U-shaped
• CPC Class Codes: B01D 63/16 Rotary, reciprocated or vibrated modules
• CPC Class Codes: B01D 65/02 Membrane cleaning or sterilisation ; Membrane regeneration
• CPC Class Codes: B01D 65/08 Prevention of membrane fouling or of concentration polarisation

Abstract

A method and apparatus for removing fouling materials from the surface of a plurality of porous membranes (9) arranged in a membrane module (4) by providing, from within the module, by means (10) other than gas passing through the pores of said membranes, gas bubbles in a uniform distribution relative to the porous membrane array such that the bubbles move past the surfaces of the membranes (9) to dislodge fouling materials therefrom. The membranes (9) are arranged in close proximity to one another and mounted to prevent excessive movement therebetween. The bubbles also produce vibration and rubbing together of the membranes to further assist removal of fouling materials.

Claims

1. A method of removing fouling materials from the surface of a plurality of porous membranes arranged in a membrane module, the porous membranes forming an array, the module having a header in which one end of each of the membranes is mounted, the header connected to a source of pressurized gas, the method comprising providing, through a plurality of holes distributed throughout the header but not through the pores of said membranes, gas bubbles in a uniform distribution relative to the porous membrane array such that said bubbles move past the surfaces of and vibrate said membranes to dislodge fouling materials therefrom, said membranes being arranged in close proximity to one another and mounted to prevent excessive movement therebetween.

2. A method according to claim 1 including mounting said membranes relative to one another so as to produce a rubbing effect between said membranes when vibrated.

3. A method according to claim 1 wherein the porous membranes comprise hollow fibre membranes.

4. A method according to claim 1 including the step of providing gas bubbles from within the module by means of gas distribution holes or openings in the header used to mount the fibre membranes.

5. A method according to claim 1 including the step of providing gas bubbles from within the module by means of at least one porous tube located within the module.

6. A method according to claim 1 including the step of providing gas bubbles from within the module by means of one or more tubes positioned to output gas within the module.

7. A method according to claim 6 wherein the one or more tubes are in the form of a comb of tubes containing holes which are located within the module.

8. A membrane module comprising a plurality of porous membranes, said membranes being arranged in close proximity to one another and mounted to prevent excessive movement therebetween, the membranes forming an array, the module having a header in which one end of each of the membranes is mounted, the header connected to a source of pressurized gas so as permit formation of gas bubbles such that, in use, said gas moves through a plurality of holes distributed throughout said header but not through the pores of said membranes, and said bubbles move past the surfaces of and vibrate said membranes to dislodge fouling materials therefrom.

9. A membrane module according to claim 8 wherein said porous membranes are mounted relative to one another so as to produce a rubbing effect between said membranes when vibrated.

10. A membrane module according to claim 8 wherein the porous membranes comprise hollow fibre membranes.

11. A membrane module according to claim 10 wherein the fibre membranes are arranged in bundles surrounded by a perforated cage which serves to prevent said excessive movement therebetween.

12. A membrane module according to claim 8 wherein the header comprises gas distribution holes or openings.

13. A membrane module according to claim 12 wherein a porous sheet cooperates with the holes to provide a uniform distribution of gas bubbles.

14. A membrane module according to claim 8 wherein the module includes a porous sheet through which pressurized gas is supplied to provide said gas bubbles.

15. A membrane module according to claim 8 wherein the module includes at least one porous tube located within the module.

16. A membrane module according to claim 8 wherein the module includes one or more tubes positioned to output gas within the module.

17. A membrane module according to claim 16 wherein the one or more tubes are in the form of a comb of tubes containing holes which sit within the module.

18. A membrane module according to claim 8 wherein the membranes comprise porous hollow fibres, the fibres having a lower end and an upper end and being fixed at the lower end in a lower header, the lower header having a plurality of holes formed therein through which gas is introduced to provide the gas bubbles.

19. A membrane module according to claim 8, the fibres having a lower end and an upper end and being fixed at the lower end in a lower header and at the upper end in an upper header, wherein the fibres are sealed at the lower end and open at the upper end to allow removal of filtrate.

20. A membrane module according to claim 19 wherein the fibres are mounted in a substantially taut manner between said headers.

30. A filtration system including a membrane module according to claim 8 wherein said membrane module is positioned vertically in a tank containing feed liquid to be filtered, and including means to apply a transmembrane pressure to said membranes in said module to cause filtrate to pass through pores in said membranes and means to connect continually or intermittently a supply of pressurized gas to a means for providing bubbles such that said gas bubbles move upwardly and uniformly between said membranes to scour the outer surfaces thereof.

31. The filtration system according to claim 30 wherein a backwash is used in conjunction with the scouring process to assist solids removal from the membrane pores and outer surface of the membranes.

32. The filtration system according to claim 31 including means to periodically drawn down a liquid within the tank to remove liquid containing accumulated solids scoured from said membranes.

33. A method of liquid filtration using a membrane module according to claim 8, comprising:

positioning the membrane module substantially vertically in a tank containing a feed liquid to be filtered;

applying a transmembrane pressure to said membranes in said module to cause a filtrate to pass through pores in said membranes; and

connecting continually or intermittently said source of pressurized gas to said header such that said gas bubbles formed move upwardly and uniformly between said membranes to scour the outer surfaces thereof.

34. The method according to claim 33, further comprising:

periodically drawing down a liquid within the tank to remove the liquid containing accumulated solids scoured from said membranes.

21. A membrane module comprising a plurality of porous hollow membrane fibres extending longitudinally between and mounted at each end to a respective potting head, said membrane fibres being arranged in close proximity to one another and mounted to prevent excessive movement therebetween, one of said potting heads having a distributed array of aeration holes formed therein, said aeration holes and said fibres being substantially uniformly mounted in said one potting head relative to said aeration holes and said one potting head is connected to a source of pressurized gas such that said pressurized gas is communicated to said array of aeration holes, and wherein said distributed array of said aeration holes is not solely peripheral to the distribution of said fibers in said header.

22. A membrane module according to claim 21 wherein said aeration holes are sized and located such that bubbles, formed by said pressurized gas passing therethrough when the module is immersed in a liquid, pass substantially uniformly between each membrane.

23. A membrane module according to claim 22 wherein said porous membranes are arranged to be vibrated by means of said gas bubbles.

24. A membrane module according to claim 23 wherein said porous membranes are mounted relative to one another so as to produce a rubbing effect between said membranes when vibrated.

25. A membrane module according to claim 22 wherein the fibres are mounted in a substantially taut manner between said potting heads.

26. A method of removing accumulated solids from the surface of a plurality of porous hollow fibre membranes mounted and extending longitudinally in an array to form a membrane module, said membranes being arranged in close proximity to one another and mounted to prevent excessive movement therebetween, the method comprising the steps of providing, from within said array, by means other than gas passing through the pores of said membranes, uniformly distributed gas bubbles, said distribution being such that said bubbles pass substantially uniformly between each membrane in said array to scour the surface of and vibrate said membranes and remove accumulated solids from within the membrane module.

27. A method according to claim 26 including mounting said membranes relative to one another so as to produce a rubbing effect between said membranes when vibrated.

28. A method according to claim 26 wherein said membranes are mounted vertically to form said array and said bubbles pass generally parallel to the longitudinal extent of said fibres.

29. A method according to claim 28 wherein said uniformly distributed gas bubbles are provided at the lower end of the array.

35. A method of forming openings in a membrane pot comprising the steps of:

providing a mould for potting membrane ends, said mould having provided therein formations for forming said opening during the potting process;

positioning said membrane ends in said mould which is filled with a curable potting material;

allowing said potting material to at least partially cure; and

demoulding said membranes.