SYSTEM AND METHOD FOR POINT OF USE/POINT OF ENTRY WATER TREATMENT
Water treatment systems and methods are provided to beneficially use the concentrate stream for other, non-potable, use. Embodiments of the invention use the distribution pressure to drive the membrane process and are configured in line with household plumbing so the concentrate is directed through the treatment system but bypassing the treatment mechanism to other uses in the building. In embodiments of this system, only the purified water that is needed for potable consumption is extracted from the water with the rest proceeding to its intended destination at the same pressure.
1 . A water treatment system, comprising:
a vessel configured to hold a volume of a liquid containing membrane foulants, the vessel having an inlet and a permeate outlet, the vessel installed in line with a water feed line; and
a membrane element disposed within the pressure vessel, the membrane element having one or more membrane sheets spaced apart at a spacing from about 1 mm to about 8 mm; and
an antifouling apparatus configured to deliver a supply of antifouling particles to the liquid, wherein the antifouling particles are configured to coat membrane surfaces of the membrane element to form a protective layer that attracts and holds membrane foulants while allowing passage of permeate through the membrane element;
wherein the spacing of the membrane sheets of the membrane element is configured to reduce a longitudinal head loss of the water feed such that a concentrate stream maintains a preselected distribution pressure.
2 . The system of claim 1 , wherein the membrane element is a spiral-wound membrane element.
3 . The system of claim 1 , wherein the membrane element is a reverse-osmosis or nanofiltration membrane element.
4 . The system of claim 1 , wherein the antifouling particles have a specific surface area of 10 m 2 /g or more.
5 . The system of claim 1 , wherein the antifouling particles have a specific surface area of 30 m 2 /g or more.
6 . The system of claim 1 , wherein the antifouling particles have a specific surface area of 500 m 2 /g or more.
7 . The system of claim 1 , wherein the antifouling particles have a major dimension of 0.5 microns or more.
8 . The system of claim 1 , wherein the antifouling particles have a major dimension of 1.0 micron or more.
9 . The system of claim 1 , wherein the antifouling particles are configured to adsorb membrane foulants having a diameter of 1 micron or less.
10 . The system of claim 1 , wherein the antifouling particles comprise diatomaceous earth.
11 . The system of claim 1 , wherein the antifouling particles comprise activated carbon.
12 . The system of claim 1 , wherein the one or more membrane sheets of the membrane element are spaced apart at a spacing of at least 3 mm.
13 . The system of claim 1 , further comprising a supply of pellets configured to inhibit the buildup of membrane foulants on the membrane element.
14 . The system of claim 13 , wherein a volume of the pellets is between about 0.5% and about 10% of the volume of the liquid.
15 . The system of claim 13 , wherein the pellets have a density greater than about 1.0 g/mL.
16 . The system of claim 13 , wherein the pellets have nonspherical shape.
17 . The system of claim 13 , wherein the pellets have a major dimension which is less than or equal to about half the spacing between the one or more membrane sheets of the spiral-wound reverse osmosis or nanofiltration membrane element.
18 . A method of treating a liquid containing membrane foulants, the method comprising:
supplying a liquid containing membrane foulants to a vessel, the vessel having an inlet, a permeate outlet, and a membrane element disposed within the vessel, the vessel installed in line with a water feed line, the membrane element having one or more membrane sheets spaced apart at a spacing of from about 1 mm to about 8 mm;
coating membrane surfaces of the membrane element to form a protective layer that attracts and holds membrane foulants while allowing passage of permeate through the membrane element;
applying a pressure differential across the membrane element so as to drive a filtration process across the membrane element, wherein the spacing of the membrane sheets reduces a longitudinal head loss of the water feed line such that the feed line or a concentrate stream maintains a distribution pressure; and
collecting the permeate from the permeate outlet in a collection vessel such that as the volume of permeate in the collection vessel increases the pressure differential across the membrane element decreases to slow the filtration process across the membrane element.
19 . The method of claim 18 , wherein the membrane element is a spiral-wound membrane element.
20 . The method of claim 18 , wherein the membrane element is a reverse-osmosis or nanofiltration membrane element.
21 . (canceled)
22 . (canceled)