Nanofiltration system for water softening with internally staged spiral wound modules
First Claim
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1. A process comprising the steps of, a) providing a multi-stage spiral wound hardness rejecting module of membranes having a feed/concentrate side and a permeate side;
- b) flowing pressurized feed water through the feed/concentrate side of the module in a single pass, the feed water having a superficial velocity of between 0.05 and 0.4 feet per second over the last portion of membranes on the feed/concentrate side of the module; and
, c) collecting at least 70% of the feed water as permeate from the permeate side of the module.
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Abstract
A spiral wound membrane filtration module is operated with a single pass through the feed side and without cross-flow on the permeate side. Recovery is 70% or more and feed side velocities are between 0.05 and 0.4 feet per second. The module may have dams in the spacer material on the shell/feed side to provide a feed path with multiple passes across the membrane leaves. A small-scale system for using such a module, for example to soften and filter water with a nanofiltration membrane, is described. The system includes a chemical cleaning apparatus and process.
100 Citations
58 Claims
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1. A process comprising the steps of,
a) providing a multi-stage spiral wound hardness rejecting module of membranes having a feed/concentrate side and a permeate side; -
b) flowing pressurized feed water through the feed/concentrate side of the module in a single pass, the feed water having a superficial velocity of between 0.05 and 0.4 feet per second over the last portion of membranes on the feed/concentrate side of the module; and
,c) collecting at least 70% of the feed water as permeate from the permeate side of the module. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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- 23. A spiral wound RO, NF or UF module adapted for use in liquid filtration and having one or more leaves of membrane material wrapped around a mandrel and mounted in a shell, having the shell side of the membrane material as the feed side, having spacer material on the feed side between adjacent leaves or parts of a leaf, and the feed path having multiple passes through the spacer material and across the outer surfaces of the leaf or leaves of the module.
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34. An apparatus comprising,
a) a membrane module contained in a shell with a feed/concentrate side into where feed water enters and from where concentrate exits, and a permeate side from where treated water exits, wherein the feed/concentrate side is configured to provide multiple flow passes; -
b) a feed pump connected to the feed/concentrate side of the module;
c) a conduit or passage for concentrate to flow from the module to drain or another apparatus;
d) an inlet for feed to enter the feed pump; and
,e) an outlet for permeate to exit the module. - View Dependent Claims (35, 36, 37)
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38. A process comprising the steps of:
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a) providing a spiral wound UF module having a feed/concentrate side and a permeate side;
b) flowing pressurized feed water through the feed/concentrate side of the module in a single pass, the feed water having a superficial velocity of between 0.05 and 0.4 feet per second over the last portion of membranes on the feed/concentrate side of the module; and
,c) collecting at least 70% of the feed water as permeate from the permeate side of the module. - View Dependent Claims (39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58)
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Specification