Low scale potential water treatment
View Patent ↗An electrochemical treating device having low scale potential is disclosed. The device has a variety of configurations directed to the layering of the anionic exchange and cationic exchange. The treatment device can also comprise unevenly sized ion exchange resin beads and/or have at least one compartment that provides a dominating resistance that results in a uniform current distribution throughout the apparatus.
1. An electrodeionization apparatus comprising:
a depleting compartment at least partially defined by a cation selective membrane and an anion selective membrane; and
a concentrating compartment at least partially defined by the anion selective membrane and containing a first layer of anion exchange media and a second layer of media disposed downstream of the first layer, the second layer comprising a first zone comprising cation exchange media that is substantially separated from the anion selective membrane by a second zone comprising anion exchange media.
2. The electrodeionization apparatus of claim 1 , further comprising a third layer.
3. The electrodeionization apparatus of claim 2 , wherein the third layer comprises at least one of an active media and an inert media.
4. The electrodeionization apparatus of claim 1 , wherein the first zone and the second zone are linearly distributed along the length of the concentrating compartment.
5. The electrodeionization apparatus of claim 1 , wherein a distribution gradient of cation exchange media and anion exchange media is disposed between the first zone and the second zone.
6. The electrodeionization apparatus of claim 1 , further comprising a third zone disposed between the first zone and the second zone.
7. The electrodeionization apparatus of claim 6 , wherein the third zone comprises at least one of inert media, cation exchange media, anion exchange media, and mixtures thereof.
8. The electrodeionization apparatus of claim 1 , comprising a plurality of concentrating compartments.
9. The electrodeionization apparatus of claim 8 , comprising a plurality of depleting compartments.
10. The electrodeionization apparatus of claim 9 , constructed and arranged to provide serial flow through the plurality of concentrating compartments.
11. The electrodeionization apparatus of claim 10 , constructed and arranged to provide parallel flow through the depleting compartments.
12. A method of treating water comprising:
introducing water to be treated into a depleting compartment of an electrodeionization device, the depleting compartment having at least one layer of ion exchange media; and
promoting transport of at least a portion of anionic species from the water introduced into the depleting compartment from a first layer of ion exchange media into a first concentrating compartment to produce water having a first intermediate quality, the first concentrating compartment defined at least partially by an anion selective membrane and a cation selective membrane, the first concentrating compartment containing at least partially a first zone comprising cation exchange media that is substantially separated from the anion selective membrane by a second zone comprising anion exchange media.
13. The method of claim 12 , further comprising maintaining a fluid flow velocity of greater than 2 gallons per minute per square foot through the first concentrating compartment.
14. The method of claim 12 , further comprising cooling the water to be treated prior to introducing the water to be treated into the depleting compartment of the electrodeionization device.
15. The method of claim 14 , wherein cooling the water to be treated comprises cooling the water to below about 12.5° C.
16. The method of claim 12 , further comprising sequentially introducing the water into the first concentrating compartment and downstream concentrating compartments.
17. The method of claim 16 , wherein sequentially introducing the water into the first concentrating compartment and the plurality of downstream concentrating compartments provides a greater recovery and a lower fluid flow velocity than introducing the water into the first concentrating compartment and the plurality of downstream concentrating compartments in parallel.
18. The method of claim 16 , further comprising adding an acidic solution into at least one concentrating compartment.