Membrane filtration device and process
First Claim
1. A process for filtering water comprising the steps of:
- (a) maintaining a level of water in a tank above a first level so as to immerse membranes while filtered permeate is withdrawn through the membranes;
(b) stopping the flow of feed water while continuing to permeate to reduce the level of water in the tank to a second level below the first level; and
(c) backwashing the membranes.
2 Assignments
0 Petitions
Accused Products
Abstract
An element for use in ultrafiltration or microfiltration of potable water has a large number of small diameter hollow fibre membranes attached between two headers. Side plates attached to the sides of the headers define vertical flow channels containing the membranes. The elements may be placed side by side and stacked on top of each other to form cassettes having continuous vertical flow channels through the entire cassette. The membrane modules or cassettes may be arranged to cover a substantial part of the cross sectional area of an open tank. Tank water may flow upwards or downwards through the flow channels. A tank may be deconcentrated by at least partially emptying and refilling the tank with fresh water while permeation continues. Excess tank water created during deconcentration may flow generally upwards through the modules and out through a retentate outlet or overflow at the top of the tank.
80 Citations
11 Claims
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1. A process for filtering water comprising the steps of:
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(a) maintaining a level of water in a tank above a first level so as to immerse membranes while filtered permeate is withdrawn through the membranes;
(b) stopping the flow of feed water while continuing to permeate to reduce the level of water in the tank to a second level below the first level; and
(c) backwashing the membranes. - View Dependent Claims (2)
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3. A filtering reactor comprising:
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a) an open tank;
b) a plurality of filtering membranes occupying substantially all of the horizontal cross-sectional area of the tank, to withdraw a filtered permeate;
c) an inlet to add feed to the tank from below the membranes; and
,d) an outlet to discharge water from the tank containing retained solids.
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4. A process for filtering water comprising the steps of,
a) providing a filtering reactor comprising, i) a tank at ambient pressure; -
ii) one or more modules of suction driven filtering membranes in the tank for withdrawing a filtered permeate;
iii) an inlet to add feed water to the tank; and
,iv) retentate outlet to discharge water containing retained solids from the tank;
wherein v) the one or more modules may be backwashed with a liquid comprising permeate;
vi) the one or more modules have a surface area of at least 500 square meters for every square meter of horizontal cross-sectional area of the tank;
vii) the one or more modules cover more than 90% of the horizontal cross-sectional area of the tank;
viii) the one or more modules are divided into elements, each element having a pair of opposed headers;
ix) the elements are separated from each other by impervious plates; and
,x) channels are provided for water to flow vertically through the elements;
b) in repeated cycles, (i) permeating filtered water while adding a sufficient volume of feed water to the tank to keep the membranes submerged; and
(ii) performing a deconcentration step further comprising at least one or both of (A) providing a flow of feed water into the tank from below the modules or (B) backwashing the one or more membrane modules with a liquid comprising permeate, wherein excess water containing retained solids flows out of the retentate outlet. - View Dependent Claims (5, 6)
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7. A filtration apparatus comprising,
(a) an element of filtering hollow fiber membranes having, (i) a pair of opposed horizontally spaced, vertically extending solid bodies; -
(ii) a plurality of hollow fibre membranes attached to and suspended between the pair of solid bodies, the hollow fibre membranes having each at least one open end and an outer surface, the outer surfaces of the open ends of the hollow fibre membranes connected to at least one solid body with a water impermeable connection; and
,(iii) one or more permeate channels in at least one of the solid bodies in fluid communication with the interior of the hollow fibre membranes for collecting a permeate drawn through the hollow fibre membranes;
(b) a vessel for holding water to be filtered;
(c) a structure for restraining the element in the vessel wherein the restraint provided by the vessel releasable in a direction substantially normal to the headers of the element. - View Dependent Claims (8, 9, 10, 11)
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Specification