Method for purifying aqueous suspension

• US 6,322,703 B1
• Filed: 02/02/2000
• Issued: 11/27/2001
• Est. Priority Date: 04/20/1999
• Status: Expired due to Term

• Current Assignee: Asahi Kasei Kabushiki Kaisha (Asahi Kasei Corporation)
• Original Assignee: Asahi Kasei Kabushiki Kaisha (Asahi Kasei Corporation)
• Inventors: Taniguchi, Tohru, Suga, Nobuhiko, Otoyo, Takehiko
• Primary Examiner(s): Drodge, Joseph W.
• Application Number:
  US09/496,590
• Time in Patent Office: 664 Days
• Field of Search: 210/85, 210/87, 210/96.1, 210/106, 210/108, 210/321.69, 210/500.23, 210/636, 210/650, 210/739, 210/745, 210/791, 210/651
• US Class Current: 210/636
• CPC Class Codes: B01D 2321/04 Backflushing
• CPC Class Codes: B01D 2321/162 Use of acids
• CPC Class Codes: B01D 2321/168 Use of other chemical agents
• CPC Class Codes: B01D 2321/185 Aeration
• CPC Class Codes: B01D 2321/2066 Pulsated flow
• CPC Class Codes: B01D 61/14 Ultrafiltration; Microfiltration
• CPC Class Codes: B01D 61/145 Ultrafiltration
• CPC Class Codes: B01D 61/147 Microfiltration
• CPC Class Codes: B01D 61/20 Accessories; Auxiliary operations
• CPC Class Codes: B01D 63/02 Hollow fibre modules
• CPC Class Codes: B01D 63/0233 forming the bundle
• CPC Class Codes: B01D 63/025 Bobbin units
• CPC Class Codes: B01D 63/06 Tubular membrane 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
• CPC Class Codes: B01D 69/00 Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
• CPC Class Codes: B01D 69/08 Hollow fibre membranes manufacture of hollow fibres D01D5/24, D01F1/08
• CPC Class Codes: B01D 69/084 Undulated fibres
• CPC Class Codes: C02F 1/441 by reverse osmosis
• CPC Class Codes: C02F 1/444 by ultrafiltration or microfiltration
• CPC Class Codes: C02F 1/78 : with ozone C02F1/4672 takes precedence
• CPC Class Codes: C02F 2303/16 : Regeneration of sorbents, filters

Abstract

A method and apparatus for purifying an aqueous suspension comprising feeding an aqueous suspension containing fine particles comprising an inorganic component from the outer surface of a wavy hollow fiber membrane having an outer diameter of from 0.5 to 3.1 mm to filter, followed by physical wash of the hollow fiber membrane. The purifying method can reduce the damage of the membrane outer surface during the physical wash step, prevent open pores on the surface from covering and achieve stable filtration. The hollow fiber membrane bundle can be produced by having a pulsation flow contacted with the hollow fiber material being extruded from the double spinning nozzle under specific conditions and cooling and solidifying or coagulating it while shaking.

Claims

1. A method for purifying an aqueous suspension comprising:

feeding the aqueous suspension containing fine particles comprising an inorganic component from outer surfaces to inner surfaces of wavy hollow fiber membranes, which are collected with a bulkiness of from 1.45 to 2.00, and which each have an outer diameter from 0.5 to 3.1 mm and a flatness of from 0.8 to 1.0 to filter said aqueous suspension;

the hollow fiber membranes having a bulkiness and being mounted or packed so as to substantially prevent rubbing of the membranes against each other during physical washing, and

physically washing the hollow fiber membranes.

2. The method according to claim 1, wherein filtration time is controlled so an amount of suspended solids accumulating is from 0.005 to 10, wherein the amount of suspended solids accumulating is defined by the following formula:

3. The method according to claim 1, wherein the physically washing is at least one selected from the group consisting of back wash, air-scrubbing and flushing.

4. The method according to claim 1, wherein the physically washing comprises back wash followed by air-scrubbing.

5. The method according to claim 1, wherein the physically washing comprises air-scrubbing and back wash performed simultaneously after the filtration.

6. The method according to claim 1, wherein the physically washing is comprises:

air-scrubbing and back wash performed simultaneously after the filtration; and

flushing.

7. The method according to claim 1, wherein the wavy hollow fiber membranes each have a flatness of from 0.9 to 1.0.

8. The method according to claim 1, wherein the wavy hollow fiber membranes each have a flatness of from 0.95 to 1.0.

9. The method according to claim 1, wherein the wavy hollow fiber membranes each have an outer diameter of from 0.7 to 2.5 mm.

10. The method according to claim 1, wherein the wavy hollow fiber membranes each have an outer diameter of from 1.0 to 2.5 mm.

11. The method according to claim 1, wherein the hollow fiber membranes each have an inner diameter of from 0.3 to 1.7 mm.

12. The method according to claim 1, wherein the wavy hollow fiber membrane each have an inner diameter of 0.3 to 1.7 mm and membrane thickness of from 0.1 to 0.7 mm.

13. The method according to claim 1, wherein the wavy hollow fiber membranes each have an inner diameter of from 0.3 to 1.7 mm and membrane thickness of from 0.1 to 0.7 mm, the membrane being oriented in the same direction and mounted with a packing ratio of from 35 to 55%.

14. A method for purifying an aqueous suspension comprising:

feeding the aqueous suspension containing fine particles comprising an inorganic component from outer surfaces to inner surfaces of wavy hollow fiber membranes, each having an outer diameter from 0.5 to 3.1 mm, to filter said aqueous suspension wherein filtration time is controlled so an amount of suspended solids accumulating is from 0.005 to 10, the hollow fiber membranes having a bulkiness and being mounted or packed so as to substantially prevent rubbing of the membranes against each other during physical washing, wherein the amount of suspended solids accumulating is defined by the following formula;

15. A method for purifying an aqueous suspension comprising:

feeding the aqueous suspension containing fine particles comprising an inorganic component from outer surfaces to inner surfaces of wavy hollow fiber membranes, which are collected with a bulkiness of from 1.45 to 2.00 and mounted in a module case with a packing ratio of from 35 to 55%, and which each have an outer diameter from 0.5 to 3.1 mm and a flatness of from 0.8 to 1.0 to filter said aqueous suspension;

the hollow fiber membranes having a bulkiness and being mounted or packed so as to substantially prevent rubbing of the membranes against each other during physical washing, and

physically washing the hollow fiber membranes.