Spiral wound membrane element, spiral wound membrane module and treatment system employing the same as well as running method and washing method therefor

• US 20020027111A1
• Filed: 07/18/2001
• Published: 03/07/2002
• Est. Priority Date: 07/18/2000
• Status: Active Grant

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: Ishihara, Satoru, Ishii, Katsumi, Ando, Masaaki
• Granted Patent: US 6,733,675 B2
• Time in Patent Office: Days
• US Class Current: 210/791
• CPC Class Codes: B01D 2311/04 Specific process operations in the feed stream; Feed pretreatment
• CPC Class Codes: B01D 2311/12 Addition of chemical agents
• CPC Class Codes: B01D 2311/14 Pressure control
• CPC Class Codes: B01D 2311/2642 Aggregation, sedimentation, flocculation, precipitation or coagulation
• CPC Class Codes: B01D 2311/2661 Addition of gas
• CPC Class Codes: B01D 2321/04 Backflushing
• CPC Class Codes: B01D 2321/16 Use of chemical agents
• CPC Class Codes: B01D 2321/28 by soaking or impregnating
• CPC Class Codes: B01D 2325/24 Mechanical properties, e.g. strength
• CPC Class Codes: B01D 61/145 Ultrafiltration
• CPC Class Codes: B01D 61/146 comprising multiple ultrafiltration steps
• CPC Class Codes: B01D 61/149 Multistep processes comprising different kinds of membrane processes selected from ultrafiltration or microfiltration
• CPC Class Codes: B01D 61/16 Feed pretreatment
• CPC Class Codes: B01D 63/101 Spiral winding
• CPC Class Codes: B01D 63/12 comprising multiple spiral-wound assemblies
• CPC Class Codes: B01D 65/02 Membrane cleaning or sterilisation ; Membrane regeneration
• CPC Class Codes: B01D 65/022 Membrane sterilisation
• CPC Class Codes: B01D 69/1071 Woven, non-woven or net mesh
• CPC Class Codes: B01D 71/68 Polysulfones; Polyethersulfones
• CPC Class Codes: C02F 1/444 by ultrafiltration or microfiltration

Abstract

A spiral wound membrane module comprises a spiral wound membrane element including a separation membrane having high back pressure strength. In filtration running, raw water introduced from a raw water inlet of a pressure vessel is subjected to dead end filtration, and permeate is taken out from a permeate outlet. In washing, wash water containing a chemical having a contaminant separating function is introduced from an end of a water collection pipe through the permeate outlet for performing back wash reverse filtration with a back pressure of 0.05 to 0.3 MPa. The filtration running is temporarily stopped for maintaining the pressure vessel in a state sealed with the raw water and the permeate for a prescribed time. Thus, contaminants adhering to the membrane surface of the spiral wound membrane element are separated. A treatment system is formed by connecting units comprising spiral wound membrane modules in parallel with each other. In the treatment system, one of the units is subjected to filtration running when another one of the units is washed. In washing, back wash reverse filtration and chemical soaking are performed.

Claims

1. A method of running a spiral wound membrane element, comprising an envelope separation membrane wound on the outer peripheral surface of a perforated hollow pipe and allowing back wash reverse filtration with a back pressure higher than 0.05 MPa and not more than 0.3 MPa,

comprising a step of feeding a raw liquid containing a chemical having a contaminant separating function or a sterilizing function from at least one end of said spiral wound membrane element and taking out a permeated liquid from at least one opening end of said perforated hollow pipe in running.

2. The method of running a spiral wound membrane element according to claim 1, wherein

said chemical is sodium hypochlorite, chloramine, hydrogen peroxide, peracetic acid or ozone.

3. The method of running a spiral wound membrane element according to claim 1, wherein

said raw liquid contains a flocculant.

4. The method of running a spiral wound membrane element according to claim 1, further comprising a step of introducing a washing liquid containing a chemical having a contaminant separating function or a sterilizing function from at least one opening end of said perforated hollow pipe and discharging the washing liquid derived from the outer peripheral surface of said perforated hollow pipe from at least one end of said spiral wound membrane element in washing thereby performing back wash reverse filtration on said separation membrane with a back pressure higher than 0.05 MPa and not more than 0.3 MPa.

5. The method of running a spiral wound membrane element according to claim 4, wherein

said washing solution is a permeated liquid.

6. The method of running a spiral wound membrane element according to claim 1, further comprising a step of feeding a washing liquid containing a chemical having a contaminant separating function or a sterilizing function from at least one end of said spiral wound membrane element and axially feeding the washing liquid containing a chemical through said spiral wound membrane element in washing.

7. The method of running a spiral wound membrane element according to claim 6, wherein

said washing liquid is a raw liquid.

8. The method of running a spiral wound membrane element according to claim 1, wherein

said separation membrane is formed by bonding a permeable membrane body to a surface of a porous sheet member, and said permeable membrane body is bonded to said surface of said porous sheet member in an anchored state.

9. A method of running a spiral wound membrane element, comprising an envelope separation membrane wound on the outer peripheral surface of a perforated hollow pipe and allowing back wash reverse filtration with a back pressure higher than 0.05 MPa and not more than 0.3 MPa,

comprising a step of introducing a washing liquid containing a chemical having a contaminant separating function or a sterilizing function from at least one end of said perforated hollow pipe and discharging the washing liquid derived from the outer peripheral surface of said perforated hollow pipe from at least one end of said spiral wound membrane element thereby performing back wash reverse filtration on said separation membrane with a back pressure higher than 0.05 MPa and not more than 0.3 MPa.

11. The method of washing a spiral wound membrane element according to claim 9, further comprising a step of regularly or periodically feeding a washing liquid containing a chemical from at least one end of said spiral wound membrane element in parallel with back wash reverse filtration performed by introducing the washing liquid containing a chemical from at least one opening end of said perforated hollow pipe.

13. The method of washing a spiral wound membrane element according to claim 9, further comprising a step of soaking said spiral wound membrane element in said washing liquid containing a chemical.

14. The method of washing a spiral wound membrane element according to claim 9, wherein

said chemical is sodium hypochlorite, chloramine, hydrogen peroxide, sulfuric acid, hydrochloric acid, nitric acid, sodium hydroxide, peracetic acid, isopropyl alcohol, oxalic acid or citric acid.

19. The method of running a spiral wound membrane element according to claim 18, wherein

said step of temporarily stopping running includes steps of:

feeding a raw liquid from an end of said spiral wound membrane element and taking out a permeated liquid from at least one opening end of said perforated hollow pipe in filtration running in said running period, and

stopping said filtration running and holding said spiral wound membrane element in said state soaked in the liquid for said prescribed time.

20. The method of running a spiral wound membrane element according to claim 18, wherein

said step of temporarily stopping running includes steps of:

introducing a washing liquid from at least one opening end of said perforated hollow pipe and discharging the washing liquid from at least one end of said spiral wound membrane element thereby performing back wash reverse filtration on said separation membrane with a back pressure higher than 0.05 MPa and not more than 0.3 MPa in back wash reverse filtration in said running period, and

stopping said back wash reverse filtration and holding said spiral wound membrane element in said state soaked in the liquid for said prescribed time.

21. The method of running a spiral wound membrane element according to claim 19, wherein

said step of temporarily stopping running further includes a step of restarting said filtration running after holding said spiral wound membrane element in said state soaked in the liquid for said prescribed time.

22. The method of running a spiral wound membrane element according to claim 19, wherein

said step of temporarily stopping running further includes a step of holding said spiral wound membrane element in said state soaked in the liquid for said prescribed time and thereafter introducing a washing liquid from at least one opening end of said perforated hollow pipe and discharging the washing liquid from at least one end of said spiral wound membrane element thereby performing back wash reverse filtration on said separation membrane with a back pressure higher than 0.05 MPa and not more than 0.3 MPa.

23. The method of running a spiral wound membrane element according to claim 20, wherein

said step of temporarily stopping running further includes a step of holding said spiral wound membrane element in said state soaked in the liquid for said prescribed time and thereafter restarting said back wash reverse filtration.

24. The method of running a spiral wound membrane element according to claim 20, wherein

said step of temporarily stopping running further includes a step of holding said spiral wound membrane element in said state soaked in the liquid for said prescribed time and thereafter feeding a raw liquid from an end of said spiral wound membrane element and taking out a permeated liquid from at least one opening end of said perforated hollow pipe thereby performing filtration running.

25. The method of running a spiral wound membrane element according to claim 19, wherein

said step of temporarily stopping running includes a step of holding said spiral wound membrane element in said state soaked in the liquid for said prescribed time and thereafter axially feeding a raw liquid through said spiral wound membrane element thereby performing flushing.

26. The method of running a spiral wound membrane element according to claim 18, wherein

said step of temporarily stopping running includes a step of feeding a liquid containing a chemical having a sterilizing function or a contaminant separating function to said spiral wound membrane element and soaking said spiral wound membrane element in said liquid containing said chemical.

27. The method of running a spiral wound membrane element according to claim 18, wherein

said separation membrane is formed by bonding a permeable membrane body to a surface of a porous sheet member, and said permeable membrane body is bonded to said surface of said porous sheet member in an anchored state.

29. The method of running a spiral wound membrane module according to claim 28, wherein

said liquid contains a chemical having a sterilizing function or a contaminant separating function.

10. A method of washing a spiral wound membrane element, comprising an envelope separation membrane wound on the outer peripheral surface of a perforated hollow pipe and allowing back wash reverse filtration with a back pressure higher than 0.05 MPa and not more than 0.3 MPa,

comprising a step of feeding a washing liquid containing a chemical having a contaminant separating function or a sterilizing function from at least one end of said spiral wound membrane element and axially feeding the washing liquid containing a chemical through said spiral wound membrane element.

12. The method of washing a spiral wound membrane element according to claim 10, further comprising a step of regularly or periodically feeding a washing liquid containing a chemical from at least one end of said spiral wound membrane element in parallel with back wash reverse filtration performed by introducing the washing liquid containing a chemical from at least one opening end of said perforated hollow pipe.

15. A method of running a spiral wound membrane module, comprising a pressure vessel having a raw liquid inlet and one or a plurality of spiral wound membrane elements stored in said pressure vessel, each spiral wound membrane element comprising an envelope separation membrane wound on the outer peripheral surface of a perforated hollow pipe and allowing back wash reverse filtration with a back pressure higher than 0.05 MPa and not more than 0.3 MPa,

comprising a step of feeding a raw liquid containing a chemical having a contaminant separating function or a sterilizing function from at least one end of said spiral wound membrane element through said raw liquid inlet of said pressure vessel and taking out a permeated liquid from at least one opening end of said perforated hollow pipe in running.

16. A method of washing a spiral wound membrane module, comprising a pressure vessel and one or a plurality of spiral wound membrane elements stored in said pressure vessel, each spiral wound membrane element comprising an envelope separation membrane wound on the outer peripheral surface of a perforated hollow pipe and allowing back wash reverse filtration with a back pressure higher than 0.05 MPa and not more than 0.3 MPa,

comprising a step of introducing a washing liquid containing a chemical having a contaminant separating function or a sterilizing function from at least one opening end of said perforated hollow pipe and discharging the washing liquid derived from the outer peripheral surface of said perforated hollow pipe from at least one end of said spiral wound membrane element for taking out the washing liquid from said pressure vessel thereby performing back wash reverse filtration on said separation membrane with a back pressure higher than 0.05 MPa and not more than 0.3 MPa.

17. A method of washing a spiral wound membrane module, comprising a pressure vessel and one or a plurality of spiral wound membrane elements stored in said pressure vessel, each spiral wound membrane element comprising an envelope separation membrane wound on the outer peripheral surface of a perforated hollow pipe and allowing back wash reverse filtration with a back pressure higher than 0.05 MPa and not more than 0.3 MPa,

comprising a step of feeding a washing liquid containing a chemical having a contaminant separating function or a sterilizing function from at least one end of said spiral wound membrane element, axially feeding the washing liquid containing a chemical through said spiral wound membrane element and taking out the washing liquid from said pressure vessel.

18. A method of running a spiral wound membrane element, comprising an envelope separation membrane wound on the outer peripheral surface of a perforated hollow pipe and allowing back wash reverse filtration with a back pressure higher than 0.05 MPa and not more than 0.3 MPa,

comprising a step of temporarily stopping running and holding said spiral wound membrane element in a state soaked in a liquid for a prescribed time in a running period.

28. A method of running a spiral wound membrane module, comprising a pressure vessel having a raw liquid inlet and one or a plurality of spiral wound membrane elements stored in said pressure vessel, each spiral wound membrane element comprising an envelope separation membrane wound on the outer peripheral surface of a perforated hollow pipe and allowing back wash reverse filtration with a back pressure higher than 0.05 MPa and not more than 0.3 MPa,

comprising a step of temporarily stopping running in a running period and holding said pressure vessel in a state filled with a liquid and sealed for a prescribed time.

30. A method of running a treatment system, comprising a plurality of spiral wound membrane modules, connected in parallel with each other, each comprising a pressure vessel having a raw liquid inlet and one or a plurality of spiral wound membrane elements stored in said pressure vessel, each spiral wound membrane element comprising an envelope separation membrane wound on the outer peripheral surface of a perforated hollow pipe and allowing back wash reverse filtration with a back pressure higher than 0.05 MPa and not more than 0.3 MPa,

comprising steps of:

feeding a raw liquid from an end of said spiral wound membrane element through said raw liquid inlet of said pressure vessel of each spiral wound membrane module and taking out a permeated liquid from said pressure vessel from at least one opening end of said perforated hollow pipe in filtration running; and

performing, when washing any of said plurality of spiral wound membrane modules, said filtration running on at least one of remaining said spiral wound membrane modules.

31. The method of running a treatment system according to claim 30, wherein

said washing includes introducing a washing liquid from at least one opening end of said perforated hollow pipe of each spiral wound membrane module and discharging the washing liquid from at least one end of said spiral wound membrane element for taking out the washing liquid from said pressure vessel thereby performing back wash reverse filtration on said separation membrane with a back pressure higher than 0.05 MPa and not more than 0.3 MPa.

32. The method of running a treatment system according to claim 30, wherein

said washing includes holding said pressure vessel of each spiral wound membrane module in a state filled with the washing liquid for a prescribed time.

33. The method of running a treatment system according to claim 32, wherein

said washing liquid is a permeated liquid or water equivalent to a permeated liquid.

34. The method of running a treatment system according to claim 32, wherein

said washing liquid contains a chemical having a contaminant separating function or a sterilizing function.

35. The method of running a treatment system according to claim 32, wherein

said washing includes introducing said washing liquid into said pressure vessel through said raw liquid inlet.

36. The method of running a treatment system according to claim 32, wherein

said washing includes introducing said washing liquid into said pressure vessel from at least one opening end of said perforated hollow pipe.

37. The method of running a treatment system according to claim 30, further comprising steps of:

connecting a raw liquid feeding pipe and a washing liquid discharge pipe to said raw liquid inlet of each spiral wound membrane module while connecting a permeated liquid takeout pipe and a washing liquid feeding pipe to at least one opening end of said perforated hollow pipe, inserting a first valve in said raw liquid feeding pipe, inserting a second valve in said washing liquid discharge pipe, inserting a third valve in said permeated liquid takeout pipe and inserting a fourth valve in said washing liquid feeding pipe, and

switching said filtration running and said washing of each spiral wound membrane module through an operation of opening/closing said first, second, third and fourth valves.

39. The treatment system according to claim 38, wherein

said passage switching means includes:

a raw liquid feeding pipe and a washing liquid discharge pipe connected to said raw liquid inlet of each spiral wound membrane module,

a permeated liquid takeout pipe and a washing liquid feeding pipe connected to at least one opening end of said perforated hollow pipe,

a first valve inserted in said raw liquid feeding pipe,

a second valve inserted in said washing liquid discharge pipe,

a third valve inserted in said permeated liquid takeout pipe, and

a fourth valve inserted in said washing liquid feeding pipe.

40. The treatment system according to claim 39, wherein

each of said first to fourth valves is an automatic valve, and

said passage switching means further includes control means controlling an operation of opening/closing each of said first to fourth automatic valves.

41. The treatment system according to claim 40, wherein

said control means controls said operation of opening/closing each of said first to fourth automatic valves on the basis of time setting.

42. The treatment system according to claim 40, wherein

said control means controls said operation of opening/closing each of said first to fourth automatic valves in response to the pressure or the flow rate for feeding a raw liquid in said filtration running of each spiral wound membrane module.

43. The treatment system according to claim 40, wherein

said control means controls said operation of opening/closing each of said first to fourth automatic valves in response to the pressure in said permeate takeout pipe or the flow rate of a permeated liquid in said filtration running of said spiral wound membrane module.

44. The treatment system according to claim 40, wherein

said control means controls said operation of opening/closing each of said first to fourth automatic valves in response to the pressure difference between a raw liquid feeding side and a permeated liquid takeout side in said filtration running of each spiral wound membrane module.

45. The treatment system according to claim 38, wherein

said separation membrane is formed by bonding a permeable membrane body to a surface of a porous sheet member, and said permeable membrane body is bonded to said surface of said porous sheet member in an anchored state.

38. A treatment system comprising:

a plurality of spiral wound membrane modules connected in parallel with each other, each comprising a pressure vessel having a raw liquid inlet and one or a plurality of spiral wound membrane elements stored in said pressure vessel, each spiral wound membrane element comprising an envelope separation membrane wound on the outer periphery of a perforated hollow pipe and allowing back wash reverse filtration with a back pressure higher than 0.05 MPa and not more than 0.3 MPa;

feeding means feeding a raw liquid from an end of said spiral wound membrane element through said raw liquid inlet of said pressure vessel of each spiral wound membrane module in filtration running;

takeout means taking out a permeated liquid from said pressure vessel from at least one opening end of said perforated hollow pipe in said filtration running; and

passage switching means capable of switching a passage so that, when any of said plurality of spiral wound membrane modules is washed, at least one of remaining said spiral wound membrane modules is subjected to said filtration running.