Backwash method

• US 20060000774A1
• Filed: 10/10/2003
• Published: 01/05/2006
• Est. Priority Date: 10/10/2002
• Status: Active Grant

• Current Assignee: Evoqua Water Technologies LLC
• Original Assignee: Siemens Industry Incorporated (Siemens AG)
• Inventors: Johnson, Warren Thomas
• Granted Patent: US 7,938,966 B2
• Time in Patent Office: Days
• US Class Current: 210/636
• CPC Class Codes: B01D 2315/06 Submerged-type; Immersion type
• CPC Class Codes: B01D 2321/185 Aeration
• CPC Class Codes: B01D 61/18 Apparatus therefor
• 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 filtration arrangement including one or more membrane modules (5) positioned vertically within a feed tank (6), each membrane module (5) having one or more membranes positioned therein. An aeration hood (10) having an upper wall (11) and one or more downwardly extending side walls (12, 13) is configured to at least partially shroud the membrane modules (5) within the tank (6). The aeration hood (10) includes a number of open-ended tubes (14), each extending downwardly from the upper wall (11) and forming a respective opening (15) therein. Each tube (14) is adapted to have at least one of the modules (5) mounted therein and extending through the respective openings (15) in the upper wall (11) so as to at least partially surround an outer periphery of an associated module or modules (5). One or more aeration openings (17) are provided in each tube (14) at a location spaced from a proximal end of the tube (16). The aeration hood side wall or walls (12, 13) extend to below the location of the aeration openings (17) in the tubes (14). Gas providing means (18) feed gas into the hood (10).

Claims

1. A filtration arrangement comprising one or more membrane modules positioned vertically within a feed tank, each membrane module comprising one or more membranes positioned therein, an aeration hood comprising an upper wall and one or more downwardly extending side walls configured to at least partially shroud said membrane modules within said tank, said aeration hood comprising a number of open-ended tubes, each extending downwardly from said upper wall and forming a respective opening therein, each tube adapted to have at least one of said modules mounted therein and extending through said respective openings in the upper wall so as to at least partially surround an outer periphery of an associated module or modules, one or more aeration openings being provided in each tube at a location spaced from a proximal end of said tube, said aeration hood side wall or walls extending to below the location of said aeration openings in said tubes, and gas providing means for feeding gas into said hood.

2. A filtration arrangement according to claim 1 wherein one or more of said aeration hood side walls are formed by side walls of the feed tank with the upper wall being sealingly attached to the side wall so formed.

3. A filtration arrangement according to claim 1 wherein the aeration openings are provided at or adjacent the distal end of each tube and the aeration hood side wall or walls extend to or below the downward extent of a distal end of said tubes.

4. A filtration arrangement according to claim 1, wherein each membrane module has an associated tube surrounding an outer periphery thereof.

5. A filtration arrangement according to claim 1 wherein the openings comprise a number of through holes located around the periphery of each tube and spaced from the distal end of said tube.

6. A filtration arrangement according to claim 1 wherein the openings comprise a number of open-ended slots located around the periphery of each tube and extending upwardly from the distal end of said tube.

7. A filtration arrangement according to claim 1 wherein the gas providing means comprise an aeration header located below the aeration hood.

8. A filtration arrangement according to claim 1 wherein said at least one module comprises a sleeve surrounding the outer periphery to prevent flow of gas therethrough, said sleeve extending part way along the length of the module to define an open region at or adjacent the lower end of the module to allow flow of gas into the module through said open region, said hood being positioned to shroud the module at the location of said open region such that gas passing through said aeration openings may pass through said open region into the module membranes.

9. A method of cleaning membrane modules in arrangement according to claim 1, the method comprising the steps of:

i) suspending the filtration operation;

ii) displacing feed liquid within the aeration hood to a level below the location of said aeration openings in each tube by feeding gas into said aeration hood while maintaining a liquid seal with the distal end of each tube;

iii) passing said gas through said aeration openings into said tubes and along surfaces of membranes within each membrane module to dislodge accumulated fouling materials therefrom;

iv) recommencing the filtration operation