MEMBRANE CLEANING WITH PULSED AIRLIFT PUMP

• US 20110198283A1
• Filed: 05/29/2008
• Published: 08/18/2011
• Est. Priority Date: 05/29/2007
• Status: Active Grant

• Current Assignee: Evoqua Water Technologies LLC
• Original Assignee: Evoqua Water Technologies LLC
• Inventors: Zauner, Peter, Zha, Fufang, James, Gerin, Phelps, Roger William, Zuback, Joseph Edward
• Granted Patent: US 8,622,222 B2
• Time in Patent Office: Days
• US Class Current: 210/626
• CPC Class Codes: B01D 2313/21 Specific headers, end caps
• CPC Class Codes: B01D 2313/26 Specific gas distributors or gas intakes
• CPC Class Codes: B01D 2315/06 Submerged-type; Immersion type
• CPC Class Codes: B01D 2321/185 Aeration
• CPC Class Codes: B01D 2321/2066 Pulsated flow
• CPC Class Codes: B01D 63/024 with a single potted end
• CPC Class Codes: B01D 63/04 comprising multiple hollow fibre assemblies
• 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
• CPC Class Codes: B01D 65/10 Testing of membranes or membrane apparatus; Detecting or repairing leaks
• CPC Class Codes: B01D 65/109 Testing of membrane fouling or clogging, e.g. amount or affinity
• CPC Class Codes: C02F 1/001 Processes for the treatment of water whereby the filtration technique is of importance C02F1/44 takes precedence; construction of filters in general B01D24/00 - B01D41/00
• CPC Class Codes: C02F 3/1273 Submerged membrane bioreactors
• CPC Class Codes: Y02W 10/10 Biological treatment of water, waste water, or sewage

Abstract

A method of cleaning a membrane surface immersed in a liquid medium with a fluid flow, including the steps of providing a randomly generated intermittent or pulsed fluid flow along the membrane surface to dislodge fouling materials therefrom. A membrane module is also disclosed comprising a plurality of porous membranes (6) or a set of membrane modules (5) and a device (11) for providing a generally randomly generated, pulsed fluid flow such that, in use, said fluid flow moves past the surfaces of said membranes (6) to dislodge fouling materials therefrom.

Claims

1. A method of cleaning a membrane surface immersed in a liquid medium to dislodge fouling materials therefrom comprising the steps of:

providing fluid flow in said medium; and

pulsing said fluid flow to provide a pulsed fluid flow which is random in at least one of magnitude, frequency and duration.

2. A method according to claim 1 wherein the fluid flow comprises a gas flow.

3. A method according to claim 2 wherein the gas flow comprises gas bubbles.

4. A method according to claim 1 wherein the fluid flow includes a two phase gas/liquid flow.

5. A method according to claim 4 wherein the method includes producing the pulsed two-phase gas/liquid flow using a device supplied with a flow of pressurised gas.

6. A method according to claim 5 wherein the flow of pressurised gas is essentially constant.

7. A method according to claim 1 wherein the method further includes using the pulsed two-phase gas/liquid flow in conjunction with an essentially constant two-phase gas/liquid flow.

8. A method according to claim 1 wherein the method further includes providing an additional source of gas bubbles in said liquid medium.

9. (canceled)

10. A membrane module comprising:

a plurality of porous membranes; and

a device that provides pulsed fluid flow which is random in at least one of magnitude, frequency and duration such that, in use, said fluid flow moves past the surfaces of said membranes to dislodge fouling materials therefrom.

11. A membrane module according to claim 10 wherein the fluid flow comprises a gas flow.

12. A membrane module according to claim 11 wherein the gas flow comprises gas bubbles.

13. A membrane module according to claim 11 wherein said pulsed gas flow is produced by said device provided with a supply of gas.

14. A membrane module according to claim 10 wherein the pulsed fluid flow includes a two phase gas/liquid flow.

16. A membrane module according to claim 10 wherein, the device for providing the pulsed fluid flow further includes a distributor in fluid communication with said device and the pulsed fluid flow is distributed into the modules through the distributor.

17. A membrane module according to claim 10 wherein a device is provided for each module.

18. A membrane module according to claim 10 wherein a device is provided for a number of modules.

19. A membrane module according to claim 17 wherein the pulsed fluid flow is randomly generated amongst said devices forming a random distribution pattern.

30. A membrane module according to claim 14 wherein the device includes a gaslift pump apparatus operative in response to said supply of pressurized gas from a gas source connected thereto to store and intermittently release pressurized gas and use the released gas to gaslift quantities of said liquid from a reservoir of liquid to produce said pulsed two-phase gas/liquid flow.

31. A membrane module according to claim 30 wherein said gaslift pump apparatus includes an inverted gas storage chamber for storing said gas provided by said gas source and having a closed upper end and an open lower end positioned in said reservoir of liquid, a vertical riser tube located within said gas storage chamber and having an inlet port in fluid communication with said reservoir of liquid and an outlet port in fluid communication with said membrane module, said riser tube having an opening in fluid communication with said gas storage chamber positioned for receiving said stored gas from said chamber when the level of gas within the chamber reaches a predetermined level and gaslifting the liquid through said riser tube for discharge into said module.

32. A membrane module according to claim 14 wherein the supply of gas is provided by an external tank containing pressurised gas, the tank being in fluid communication with the membrane module and having control means for providing randomly generated pulses of gas to the module to form a gas bubble flow for cleaning the membrane surfaces.

33. A membrane module according to claim 32 wherein the control means comprise a fluid flow control device positioned in a gas/liquid inlet to the membrane module and operable in dependence on the level of liquid in the inlet to provide gas from the external tank.

39. A method of operating a membrane bioreactor according to claim 33 wherein the further source of aeration comprises a group of air permeable tubes.

15. (canceled)

20. A method of removing fouling materials from the surface of a plurality of porous hollow fiber 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 a generally random, uniformly distributed pulsed gas bubble flow past the surfaces of said membranes, said distribution being such that said gas bubbles flow substantially uniformly between each membrane in said array to scour the surface of said membranes and remove accumulated solids from within the membrane module.

21. A method of removing fouling materials from the surface of a plurality of porous hollow fiber membranes according to claim 20 wherein said gas bubble flow includes a two phase gas/liquid flow.

22. A method of removing fouling materials from the surface of a plurality of porous hollow fiber membranes according to claim 21 wherein said pulsed two-phase gas/liquid flow is produced by a device provided with an essentially constant supply of gas.

23. A method of removing fouling materials from the surface of a plurality of porous hollow fiber membranes according to claim 21 wherein the pulsed gas bubble flow is random in magnitude and/or frequency and/or duration.

24. A membrane module comprising a plurality of porous hollow fiber membranes, said fiber membranes being arranged in close proximity to one another and mounted to prevent excessive movement therebetween, the fiber membranes being fixed at each end in a header, one header having one or more openings formed therein through which a generally random pulsed gas flow is introduced for cleaning the surfaces of said hollow fiber membranes.

25. A membrane module according to claim 24 wherein the pulsed gas flow is in the form of gas bubbles.

26. A membrane module according to claim 24 wherein said pulsed gas flow includes a two phase gas/liquid flow.

27. A membrane module according to claim 26 wherein said pulsed two-phase gas/liquid flow is produced by a device provided with a supply of gas.

28. A membrane module according to claim 27 wherein the supply of gas is essentially constant.

29. A membrane module according to claim 24 wherein the pulsed gas flow is random in magnitude and/or frequency and/or duration.

34. A membrane module according to claim 24 wherein the device is connected in fluid communication with a fluid distributor to substantially uniformly distribute the pulsed gas bubbles into the module.

35. A membrane bioreactor including a tank having means for the introduction of feed thereto, means for forming activated sludge within said tank, a membrane module according to claim 24 positioned within said tank so as to be immersed in said sludge and said membrane module provided with means for withdrawing filtrate from at least one end of said membranes.

36. A method of operating a membrane bioreactor according to claim 35, the method comprising introducing feed to said tank, applying a vacuum to said fibers to withdraw filtrate therefrom while providing said pulsed gas flow through aeration openings within said module such that, in use, said gas flow moves past the surfaces of said membrane fibers to dislodge fouling materials therefrom.

37. A method of operating a membrane bioreactor according to claim 36 further comprising providing a further source of aeration may be provided within the tank.

38. A method of operating a membrane bioreactor according to claim 36 wherein the membrane module is suspended vertically within the tank and said further source of aeration is provided beneath the suspended module.

40. A water treatment system including a tank:

a liquid chamber fluidly connected to the tank;

a gas chamber fluidly connected to the liquid chamber; and

a membrane module fluidly connected to the gas chamber.

41. A water treatment system according to claim 40 further including a gas transfer system having a suction side connected to the liquid chamber and a discharge side connected to the gas chamber.

42. A water treatment system according to claim 40 further including a source of gas fluidly connected to the liquid chamber.

43. A water treatment system according to claim 40 further including a membrane module vessel containing the membrane module and the membrane module vessel is hydraulically connected to the tank.

44. A water treatment system comprising a liquid reservoir fluidly connected to a source of water;

a gas/liquid chamber enclosing a first compartment and a second compartment, the first compartment fluidly connected to the liquid reservoir; and

a membrane separation vessel hydraulically connected to the second compartment.

45. A water treatment system according to claim 44 further comprising a chamber hydraulically isolated from the membrane module and a gas source connected to the chamber.

46. A water treatment system according to claim 44 wherein the membrane module is immersed in mixed liquor contained in a membrane tank and the membrane tank is hydraulically connected to the aeration zone which is fluidly connected to the chamber.

47. A method of scouring a membrane module including:

providing a chamber having a first compartment and a second compartment;

establishing a hydraulic seal between the first compartment and the membrane module;

at least partially filling the first compartment with a liquid and

introducing a gas into the chamber.

48. A method of scouring a membrane module according to claim 47 wherein the method further includes breaking the hydraulic seal, wherein breaking the hydraulic seal releases at least a portion of the gas contained in the chamber to the membrane module and then re-establishing the hydraulic seal between the first compartment and the membrane module.

49. A method of scouring a membrane module according to claim 47 wherein the method further includes re-breaking and re-establishing the hydraulic seal to produce a pulsed release of at least a portion of the gas contained in the chamber.

50. A method of scouring a membrane module according to claim 47 wherein the method includes introducing liquid into the second compartment.

51. A method of scouring a membrane module according to claim 47 wherein the introduction of the gas into the chamber is performed essentially continuously.

52. A method of cleaning filtration membranes located in a vessel containing liquid comprising the steps of:

providing a fluid within the liquid; and

randomly pulsing said fluid within the liquid at a number of locations within the vessel.

53. A method according to claim 52 wherein the pulses of fluid are random in magnitude and/or frequency and/or duration.

54. A method according to claim 52 wherein the fluid comprises a gas.

55. A method according to claim 54 wherein the gas comprises gas bubbles.

56. A method according to claim 52 wherein the fluid includes a two phase gas/liquid mixture.