| Title of Invention | "AERATION METHOD" |
|---|---|
| Abstract | A membrane filtration module (5) comprising a bundle of porous hollow membranes (6) and a gas feeder (10) fitted around a circumference of the bundle (6).Reference to Figures 1 to 4 |
| Full Text | TECHNICAL FIELD The present invention relates to membrane filtration module and more particularly to an improved backwash method and apparatus. BACKGROUND OF THE INVENTION The use of membrane filtration systems is growing rapidly. The success of such systems is largely dependent on employing effective and efficient membrane cleaning methods. Commonly used physical cleaning methods include backwash (backpulse, backflush) using liquid permeate or a gas, and membrane scrubbing or scouring using a gas in the form of bubbles in a liquid. Examples of second type of method are illustrated in United States Patent No. 5,192,456 to Ishida et al, United States Patent No. 5,248,424 to Code et al, United States Patent No. 5,639,373 to Henshaw et al, United States Patent No. 5,783,083 to Henshaw et al and our PCT application Nos W098/28066 and WOOO/18498. These prior art systems use a variety of techniques to introduce gas bubbles into the membrane arrays to produce effective and efficient surface cleaning. It has been found that effective cleaning is achieved by introducing bubbles into the array in a uniform i manner and retaining the bubbles within the array as much as possible to produce efficient cleaning of the membrane surfaces. SUMMARY OF THE INVENTION The object of the present invention is to provide a membrane filtration module comprising a bundle of porous hollow membranes and a gas feeder fitted around a circumference of the bundle. A membrane filtration module comprising a plurality of vertically disposed porous hollow membranes to be immersed in a liquid and a gas feeder configured, when in use, to feed gas bubbles into the array transversely of the vertical axis of said array According to a first aspect, the present invention provides a method of providing gas bubbles within an array of vertically disposed porous hollow membranes to clean the outer surfaces of said membranes when said array is immersed in a liquid, the method comprising the steps of feeding gas bubbles into said array transversely of the vertical axis of said array. Preferably, said method includes the step of retaining said gas bubbles within said array using a sleeve surrounding said array at least along part of its length. According to a further aspect, the present invention provides a membrane filtration module including a plurality of vertically disposed porous hollow membranes adapted, in use, to be immersed in a liquid, gas feeding means adapted to feed gas bubbles into said array transversely of the vertical axis of said array. For preference, said module further includes a sleeve surrounding said array at least along part of its length for retaining said gas bubbles within the array. Preferably, the sleeve extends along 17% or greater of the length of the array. Preferably, said porous hollow membranes comprise hollow fibre membranes. For preference, the fibre membranes are formed in a generally cylindrical bundle. For further preference, said sleeve is located adjacent and above the gas feeding means. Preferably, the gas feeding means comprises a tube adapted to extend around the periphery of the array of membranes, the tube having a plurality of openings located on its inner surface adjacent the array of membranes for feeding gas into the membrane array. For preference, a number of gas feeding means are provided along the length of the array or bundle. Preferably, the openings in the tube include extensions in the form of tubes adapted to extend into the array. For preference, the sleeve extends along a major portion of the length of said membranes. BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 shows a broken side elevation view of a hollow fibre membrane module with a gas feeding ring according to an embodiment of the invention; Figure 2 shows a perspective view of the gas feeding ring of Figure 1; Figure 3 shows a cutaway perspective view of the gas feeding ring of Figure 2; and Figure 4 shows a graph of transmembrane pressure (TMP) vs time running of a filtration module for different percentage lengths of the wrapping of the module. DESCRIPTION OF PREFERRED EMBODIMENT The preferred embodiment relates to porous hollow fibre membranes, however, it will be appreciated that the invention is not limited to such an application and is equally applicable to other similar arrays of membranes. Referring to the drawings, a fibre membrane module 5 is shown in figure 1 comprising a bundle of hollow fibre membranes 6 extending between an upper and lower potting sleeves 7 and 8, respectively. The fibre membranes 6 are supported by a screen 9 also extending between the sleeves 7 and 8. The gas feeding ring 10 is fitted around the circumference of the fibre bundle 6 at a location spaced from the lower potting sleeve 8. A tube or sleeve 11 is placed around the bundle 6 above the gas feeding ring 10 and extends along the length of the bundle the tube 11 may be formed as a solid tube or by wrapping a suitable sheet material around the fibre bundle 6. The tube material should be impervious to the gas bubbles so they are retained within the fibre bundle but need not be liquid impervious. A region 12 above and below the potting sleeves is left uncovered by the tube 11 to allow entry of feed to the fibre membranes as well as removal of material backwashed from the membranes by usual processes as well as bubbles fed into the bundle by the gas feeding ring 10. Figures 2 and 3 show the gas feeding ring 10 in more detail. The ring is an annular tube 15 having spaced holes or openings 16 formed around its inner circumference to allow gas to be fed into the fibre array when the ring is placed around the bundle as shown in Figure 1. Gas or air may be supplied to the ring 10 through a port 17 in one side of the ring. The system provides a number of advantages. Air or gas can be fed into the membrane bundle at a number of locations along its length by use of a number of gas feeding rings. This enables more uniform provision of gas scouring bubbles within the bundles. Retention of bubbles within the bundle by the tube or sleeve 11 produces a more efficient scouring of the fibre surfaces. Provision of scouring bubbles in this way, independent of the fibre headers, allows filtrate to withdrawn from either of both ends of the fibre module and allows reverse filtration from either or both ends of the fibre module when backwashing.. Figure 4 illustrates the reduction in increase of TMP with increased sleeve or wrapping length along the fibre bundle. It will also be appreciated that further embodiments and exemplifications of the invention are possible without departing from the spirit or scope of the invention described. We Claim: 1. A membrane filtration module (5) comprising a bundle of porous hollow membranes (6) mounted between headers (7, 8) to be immersed in a liquid characterized in that - gas feeder (10) is fitted around a circumference of the bundle (6), - said gas feeder (10) is configured, when in use, to direct the gas bubbles towards the bundle (6) from around a circumference of the bundle transversely of a vertical axis of the bundle (6) independently of the headers (7, 8), - said filtration module comprises a sleeve (11) positioned about the bundle along at least a part of a length of the bundle - said sleeve (11), when in use, retains the gas bubbles within the bundle. 2. The membrane filtration module as claimed in claim 1, wherein the sleeve extends along about 17% or greater of the length of the bundle. 3. The membrane filtration module as claimed in claim 2, wherein the sleeve extends along a major portion of a length of the bundle. 4. The membrane filtration module as claimed in claim 2, wherein the sleeve is situated adjacent to the gas feeder and above the gas feeder. 5. The membrane filtration module as claimed in claim 1, wherein the porous hollow membranes comprise hollow fibre membranes. 6. The membrane filtration module as claimed in claim 5, wherein the bundle is, preferably cylindrical. 7. The membrane filtration module as claimed in claim 1, wherein the gas feeder (10) comprises a tube defining a plurality of apertures (16) positioned on an inner circumference of the gas feeder (10). 8. The membrane filtration module as claimed in claim 7, wherein the gas feeder further comprises tube extensions (17) positioned about the apertures (16). 9. The membrane filtration module as claimed in claim 1, further comprising a plurality of gas feeders positioned along a length of the bundle. 10. The membrane filtration module as claimed in claim 1, further comprising a screen (9) positioned about the porous hollow membranes. 11. The use of the membrane filtration module (5) as claimed in claim 1 ,to clean the outer surfaces of said membranes, when said bundle is immersed in a liquid by directing gas bubbles towards the bundle from around a circumference of the bundle transversely of a vertical axis of the bundle. 12. A membrane filtration module substantially as herein described with reference to the accompanying drawings. |
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329-DELNP-2005-Assignment-(06-05-2009).pdf
329-DELNP-2005-Correspondence Others-(16-02-2012).pdf
329-DELNP-2005-Correspondence-Others-(06-05-2009).pdf
329-delnp-2005-correspondence-others.pdf
329-delnp-2005-correspondence-po.pdf
329-delnp-2005-description (complete).pdf
329-delnp-2005-form-13-(06-05-2009).pdf
329-DELNP-2005-Form-16-(16-02-2011)-1.pdf
329-DELNP-2005-Form-16-(16-02-2011).pdf
329-DELNP-2005-GPA-(16-02-2011).pdf
329-DELNP-2005-Others-Document-(06-05-2009).pdf
329-delnp-2005-petition-137.pdf
| Patent Number | 211186 | ||||||||
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| Indian Patent Application Number | 329/DELNP/2005 | ||||||||
| PG Journal Number | 45/2007 | ||||||||
| Publication Date | 09-Nov-2007 | ||||||||
| Grant Date | 17-Oct-2007 | ||||||||
| Date of Filing | 28-Jan-2005 | ||||||||
| Name of Patentee | U.S. FILTER WASTEWATER GROUP, INC. | ||||||||
| Applicant Address | 181 THORN HILL ROAD, OF WARRENDALE, PENNSYLVANIA, 15086, U.S.A. | ||||||||
Inventors:
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| PCT International Classification Number | B01D 65/02 | ||||||||
| PCT International Application Number | PCT/AU2003/001068 | ||||||||
| PCT International Filing date | 2003-08-21 | ||||||||
PCT Conventions:
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