Assembly for Water Filtration Using a Tube Manifold to Minimise Backwash

• US 20080190846A1
• Filed: 08/22/2006
• Published: 08/14/2008
• Est. Priority Date: 08/22/2005
• Status: Active Grant

• Current Assignee: Evoqua Water Technologies LLC
• Original Assignee: Evoqua Water Technologies LLC
• Inventors: Johnson, Warren Thomas, Cox, David John
• Granted Patent: US 8,858,796 B2
• Time in Patent Office: Days
• US Class Current: 210/636
• CPC Class Codes: B01D 2313/18 Specific valves
• CPC Class Codes: B01D 2313/201 Closed housing, vessels or containers
• CPC Class Codes: B01D 2313/26 Specific gas distributors or gas intakes
• CPC Class Codes: B01D 2313/48 Mechanisms for switching between regular separation operations and washing
• CPC Class Codes: B01D 2313/90 Additional auxiliary systems integrated with the module or apparatus
• CPC Class Codes: B01D 2315/06 Submerged-type; Immersion type
• CPC Class Codes: B01D 2315/18 Time sequence of one or more process steps carried out periodically within one apparatus
• CPC Class Codes: B01D 2315/20 Operation control schemes defined by a periodically repeated sequence comprising filtration cycles combined with cleaning or gas supply, e.g. aeration
• CPC Class Codes: B01D 2321/04 Backflushing
• CPC Class Codes: B01D 2321/10 Use of feed
• CPC Class Codes: B01D 2321/16 Use of chemical agents
• CPC Class Codes: B01D 61/18 Apparatus therefor
• CPC Class Codes: B01D 63/02 Hollow fibre modules
• CPC Class Codes: B01D 65/02 Membrane cleaning or sterilisation ; Membrane regeneration

Abstract

A membrane filtration assembly (10) including a membrane module (5) having one or more permeable hollow membranes (6) supported therein by at least one header (7). A filtrate collection chamber (18) is associated with the header (7) and in fluid communication with lumens of the membranes (6) for collecting filtrate withdrawn through said membrane lumens. A filtration chamber (11) is provided for receiving feed liquid to be applied to the surface of membranes (6) within the module (5). The filtration chamber (11) encloses module (5) and extends beyond the height of the module (5).

Claims

1. A membrane filtration assembly comprising:

a membrane module having one or more permeable hollow membranes supported therein by at least one header;

a filtrate collection chamber associated with said header and in fluid communication with lumens of said membranes for collecting filtrate withdrawn through said membrane lumens; and

a filtration chamber for receiving feed liquid to be applied to the surface of membranes within said module, said filtration chamber enclosing said module and extending beyond the height of said module.

2. A membrane filtration assembly according to claim 1 wherein the membranes extend between a pair of spaced, opposed headers.

3. A membrane filtration assembly according to claim 2 wherein a filtrate collection chamber is associated with one or both of said headers.

4. A membrane filtration assembly according to claim 2 of wherein said membranes are positioned vertically within said module and said headers are respective upper and lower headers.

5. A membrane filtration assembly according to claim 2 wherein said membranes are positioned generally horizontally within said module and said headers are respective side headers.

6. A membrane filtration assembly according to claim 3 wherein a filtrate carrier is provided between and it fluid communication with said filtrate collection chambers.

7. A membrane filtration assembly according to claim 6 wherein said filtrate carrier extends through said module between said headers.

8. A membrane filtration assembly according to claim 1 wherein said filtration chamber is closed at one end and open the other.

9. A membrane filtration assembly according to claim 8 wherein the open end of the filtration chamber is provided with a valve which allows gas flow therethrough while only allowing liquid flow into the filtration chamber.

10. A membrane filtration assembly according to claim 9 wherein said valve comprises a ball valve wherein a valve seat is formed by a truncated conical ceiling of the filtration chamber and said opening is formed in the truncated portion of the cone such that a ball of larger diameter than said opening is located within the filtration chamber and has a buoyancy relative to liquid within the filtration chamber such that the ball rises with the liquid level within the filtration chamber to close said opening by bearing against said valve seat.

11. A membrane filtration assembly according to claim 1 wherein the space defined between the filtration chamber and the module is, at least in part, filled with one or more filler elements.

12. A membrane filtration assembly according to claim 1 wherein an aeration backwash device is provided in fluid communication with said filtration chamber for selectively communicating gas and/or liquid to and/or from said filtration chamber.

13. A membrane filtration system according to claim 1 wherein said filtration chamber is integrally formed in one piece or comprises multiple elements.

14. A membrane filtration system according to claim 2 wherein one or both of said headers is provided with an opening or openings to allow the flow of fluid therethrough.

15. A method of operating a membrane filtration system of the type including a membrane module having one or more permeable hollow membranes supported therein by at least one header, a filtrate collection chamber associated with said header and in fluid communication with lumens of said membranes for collecting filtrate withdrawn through said membrane lumens and a filtration chamber including an opening for receiving feed liquid to be applied to the outer surface of membranes within said module;

said filtration chamber enclosing said module and extending beyond the height of said module, said method comprising the steps of;

a) providing feed liquid to the filtration chamber so as to produce a pressure differential across a membrane wall;

b) filtering liquid through the membrane wall into the membrane lumen as filtrate; and

c) withdrawing filtrate from the membrane lumen into the filtrate collection chamber.

16. A method according to claim 15 wherein said filtration chamber is located in a feed containing vessel and said method includes the step of raising the level of feed liquid within the feed containing vessel to above that of the opening in the filtration chamber to provide feed liquid into the filtration chamber.

17. A method according to claim 15 including the further step of performing an aeration operation comprising the step of:

d) aerating the membranes within the module by flowing gas bubbles past the surfaces of said membranes.

18. A method according to claim 17 including the further step of:

e) preventing liquid flow from the filtration chamber during said aeration step.

19. A method according to claim 17 wherein said filtration chamber is located in a feed containing vessel and said method includes the step of lowering the level of feed liquid within the feed containing vessel to below that of the opening in the filtration chamber before said aeration step.

20. A method according to claim 15 including the further step of performing a feed liquid backwash operation comprising the step of:

d) backwashing the membranes within the module by flowing feed liquid past the surfaces of said membranes.

21. A method according to claim 20 including the further step of:

e) preventing liquid flow from the filtration chamber during said backwashing step.

22. A method according to claim 20 wherein said filtration chamber is located in a feed containing vessel and said method includes the step of lowering the level of feed liquid within the feed containing vessel to lower than that of the opening in the filtration chamber before said backwashing step.

23. A method according to claim 20 wherein feed liquid is flowed out of said module through an opening or openings in said header.

24. A method according to claim 20 wherein said filtration chamber is located in a feed containing vessel and said method includes the step of raising the level of feed liquid within the feed containing vessel to above that of the opening in the filtration chamber to cause a flow of feed liquid into the filtration chamber before and/or during said backwash step.

25. A method according to claim 15 including the further step of performing a filtrate liquid backwash operation comprising the steps of:

d) suspending the filtration operation;

e) backwashing the membranes within the module by flowing filtrate liquid into the membrane lumens and through the walls thereof to remove accumulated solids from said membranes;

f) removing filtrate backwash liquid containing said accumulated solids from said filtration chamber.

26. A method according to claim 25 wherein said filtration chamber is located in a feed containing vessel and said method comprises the further steps of:

g) lowering the level of feed liquid within the feed containing vessel to below that of the opening in the filtration chamber before said backwashing step;

h) arranging the rate of flow of filtrate backwash liquid into the filtrate chamber and the rate of removal of filtrate backwash liquid from the filtration chamber such that no filtrate flows from the filtration chamber into said feed containing vessel.

27. A method according to claim 15 including the further step of removing liquid from said filtration chamber following said aeration operation and/or said backwash operation.

28. A method of operating a membrane filtration system of the type including a membrane module having one or more permeable hollow membranes supported therein by at least one header, a filtrate collection chamber associated with said header and in fluid communication with lumens of said membranes for collecting filtrate withdrawn through said membrane lumens and a filtration chamber including an opening for receiving feed liquid to be applied to the outer surface of membranes within said module, said opening being controlled by a valve arranged to allow flow of gas therethrough while only allowing liquid flow into said filtration chamber;

said filtration chamber enclosing said module and extending beyond the height of said module, said method comprising the steps of;

a) providing feed liquid to filtration chamber such that the valve controlling the opening in the filtration chamber is closed to prevent liquid flow out of the filtration chamber;

b) continuing to provide feed liquid to the filtration chamber to pressurize the filtration chamber and produce a pressure differential across a membrane wall;

c) filtering liquid through the membrane wall into the membrane lumen as filtrate; and

d) withdrawing filtrate from the membrane lumen into the filtrate collection chamber.

29. A method according to claim 28 including the further step of performing an aeration operation comprising the steps of:

e) opening said valve to depressurise the filtration chamber;

f) aerating the membranes within the module by flowing gas bubbles past the surfaces of said membranes.

30. A method according to claim 29 wherein said filtration chamber is located in a feed containing vessel and said method comprises the further steps of:

g) lowering the level of feed liquid within the feed containing vessel to below that of the opening in the filtration chamber before said backwashing step to cause opening of said valve;

h) preventing liquid flow from the filtration chamber into said feed containing vessel during said backwashing step.

31. A method according to claim 28 including the further step of performing a feed liquid backwash operation comprising the steps of:

e) opening said valve to depressurise the filtration chamber;

f) backwashing the membranes within the module by flowing feed liquid past the surfaces of said membranes.

32. A method according to claim 31 wherein said filtration chamber is located in a feed containing vessel and said method comprises the further steps of:

g) lowering the level of feed liquid within the feed containing vessel to below that of the opening in the filtration chamber before said backwashing step to cause opening of said valve;

h) preventing liquid flow from the filtration chamber into said feed containing vessel during said backwashing step.

33. A method according to claim 28 wherein said filtration chamber is located in a feed containing vessel and including the further step of performing a feed liquid backwash operation comprising the steps of:

e) lowering the level of feed liquid within the feed containing vessel to allow said valve to open and depressurise the filtration chamber while maintaining the level of feed liquid level above that of the opening in the filtration chamber to cause a flow of feed liquid into the filtration chamber;

f) backwashing the membranes within the module by flowing said feed liquid within the filtration chamber past the surfaces of said membranes.

34. A method according to claim 33 wherein feed liquid is flowed out of said module through an opening or openings in said header.

35. A method according to claim 28 including the further step of performing a filtrate liquid backwash operation comprising the steps of:

e) suspending the filtration operation;

f) backwashing the membranes within the module by flowing, filtrate liquid into the membrane lumens and through the walls thereof to remove accumulated solids from said membranes;

g) removing filtrate backwash liquid containing said accumulated solids from said filtration chamber.

36. A method according to claim 35 wherein said filtration chamber is located in a feed containing vessel, said method comprising the further steps of:

g) lowering the level of feed liquid within the feed containing vessel to allow said valve to open and depressurise the filtration chamber before said backwashing step; and

h) arranging the rate of flow of filtrate backwash liquid into said filtration chamber and the rate of removal of filtrate backwash liquid from the filtration chamber such that no filtrate liquid flows from the filtration chamber into said feed containing vessel.

37. A method according to claim 28 comprising the further step of removing liquid from said filtration chamber following said aeration operation and/or said backwash operation.