CLEANING IN MEMBRANE FILTRATION SYSTEMS
First Claim
1. A method of cleaning a permeable, hollow membrane, the permeable, hollow membrane comprising a wall, a filtrate side, and an outer side, the method comprising:
- removing liquid from the filtrate side of the membrane;
removing liquid from the outer side of the membrane;
applying a chemical cleaning solution to the outer side of the membrane;
causing flow of the chemical cleaning solution through the wall from the outer side of the membrane into the filtrate side to at least partially fill the filtrate side with the chemical cleaning solution by applying a pressure differential across the membrane wall;
isolating the outer side of the membrane;
causing flow of the chemical cleaning solution back to the outer side through the membrane wall by applying a pressurized gas to the filtrate side;
accumulating the increased pressure developed on the outer side of the membrane as a result of the flow of the chemical cleaning solution; and
causing flow of the chemical cleaning solution though the membrane wall from the outer side to the filtrate side under the effect of the accumulated pressure on the outer side of the membrane wall by releasing the pressure applied by the pressurized gas to the filtrate side of the membrane wall.
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Accused Products
Abstract
A method of cleaning permeable, hollow membranes (6) in an arrangement of the type wherein a pressure differential is applied across the walls (15) of the permeable, hollow membranes (6) immersed in a liquid suspension, the liquid suspension being applied to the outer surface of the porous hollow membranes (6) to induce and sustain filtration through the membrane walls (15) wherein some of the liquid suspension passes through the walls (15) of the membranes (6) to be drawn off as clarified liquid or permeate from the hollow membrane lumens (7), and at least some of the solids are retained on or in the hollow membranes (6) or otherwise as suspended solids within the liquid surrounding the membranes (6). The method of cleaning comprises the steps of applying a cleaning solution (14) to one side of the membrane wall (15); applying a pressure differential across the membrane wall (15) to cause flow of the cleaning solution (14) through the wall (15) from the one side of the membrane wall (15) to the other side of the membrane wall (15) and applying a reverse pressure differential across the membrane wall (15) to cause flow of the cleaning solution (14) through the wall (15) from the other side of the membrane wall (15) back to the one side of the membrane wall (15). A method of determining the amount of chemical cleaning solution required is also disclosed.
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Citations
30 Claims
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1. A method of cleaning a permeable, hollow membrane, the permeable, hollow membrane comprising a wall, a filtrate side, and an outer side, the method comprising:
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removing liquid from the filtrate side of the membrane;
removing liquid from the outer side of the membrane;
applying a chemical cleaning solution to the outer side of the membrane;
causing flow of the chemical cleaning solution through the wall from the outer side of the membrane into the filtrate side to at least partially fill the filtrate side with the chemical cleaning solution by applying a pressure differential across the membrane wall;
isolating the outer side of the membrane;
causing flow of the chemical cleaning solution back to the outer side through the membrane wall by applying a pressurized gas to the filtrate side;
accumulating the increased pressure developed on the outer side of the membrane as a result of the flow of the chemical cleaning solution; and
causing flow of the chemical cleaning solution though the membrane wall from the outer side to the filtrate side under the effect of the accumulated pressure on the outer side of the membrane wall by releasing the pressure applied by the pressurized gas to the filtrate side of the membrane wall. - View Dependent Claims (3, 4, 5, 6, 7, 25, 26)
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2. (canceled)
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8. A method of cleaning a permeable, hollow membrane, the permeable, hollow membrane comprising a wall, a one side, and another side, the method comprising:
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applying a chemical cleaning solution comprising at least one of an acid, a caustic solution, and an oxidizing solution to the one side of the membrane wall;
causing flow of the chemical cleaning solution though the wall from the one side of the membrane wall to the other side of the membrane wall by applying a pressure differential across the membrane wall; and
causing flow of the chemical cleaning solution through the wall from the other side of the membrane wall back to the one side of the membrane wall by applying a reverse pressure differential across the membrane wall. - View Dependent Claims (9, 10, 11, 12, 27, 28)
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13. (canceled)
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14. A method of cleaning a permeable, hollow membrane, the permeable, hollow membrane comprising a wall, a filtrate side, and an outer side, the method comprising:
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removing liquid from the filtrate side of the membrane;
removing liquid from the outer side of the membrane;
applying a chemical cleaning solution comprising at least one of an acid, a caustic solution, and an oxidizing solution to the outer side of the membrane;
causing flow of the chemical cleaning solution though the wall from the outer side of the membrane into the filtrate side of the membrane to at least partially fill the filtrate side with the chemical cleaning solution by applying a pressure differential across the membrane wall; and
causing flow of the chemical cleaning solution through the wall from the filtrate side of the membrane back to the outer side of the filtrate side by applying a reverse pressure differential across the membrane wall. - View Dependent Claims (15, 16, 29, 30)
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17-24. -24. (canceled)
Specification