Treating liquids with pH adjuster-based system
The invention features a system for treating liquid including a liquid treatment device comprising adsorbent media for removing a substance from liquid and a pH adjuster device located upstream of the liquid treatment device relative to a direction of flow of the liquid. The pH adjuster device contains particulate or solid state pH adjuster material capable of releasing H or OH groups into the liquid or consuming H or OH groups from the liquid effective to raise or lower the pH of the liquid while it passes through the media. The pH adjuster may include acidifier or basifier material. Also featured is a method of using the device to remove a substance from liquid by adsorption and/or ion exchange.
1. A method for removing a substance from liquid, comprising:
passing liquid containing a substance to be removed into a pH adjuster device, said pH adjuster device containing solid state pH adjuster material;
releasing from said pH adjuster material H or OH groups into the liquid or consuming with said pH adjuster material H or OH groups from the liquid effective to raise or lower the pH of the liquid, at a generally fixed location relative to a liquid treatment device;
passing the liquid having the raised or lowered pH into said liquid treatment device that is located downstream of said pH adjuster device relative to a direction of flow of the liquid, said liquid treatment device comprising adsorbent media; and
removing the substance from the liquid with said media by a mechanism selected from the group consisting of adsorption, ion exchange and combinations thereof.
2. The method of claim 1 wherein passing the liquid into said liquid treatment device at said lowered pH increases a capacity of said media to remove arsenic-containing chemical species from the liquid by at least about a factor of 4.
3. The method of claim 1 comprising releasing H or consuming OH groups from the liquid via said pH adjuster material effective to lower the pH of the liquid.
4. The method of claim 3 comprising removing arsenic-containing chemical species from the liquid with said media to levels under 2 parts per billion.
5. The method of claim 4 wherein the liquid is drinking water.
6. The method of claim 3 wherein said media is selected from the group consisting of zirconium-based media, iron-based media, titanium-based media and combinations thereof.
7. The method of claim 3 comprising hydrolytically decomposing said pH adjuster material so as to consume said OH from the liquid.
8. The method of claim 7 wherein said pH adjuster material is selected from the group consisting of zirconium basic sulfate, zirconium basic carbonate, titanium basic sulfate, and combinations thereof.
9. The method of claim 3 comprising conducting ion exchange substitution of protons from said pH adjuster material into the feed liquid.
10. The method of claim 9 wherein said pH adjuster material is selected from the group consisting of zirconium phosphates, zirconium silicates, titanium phosphates, cation exchange resins and combinations thereof.
11. The method of claim 3 comprising removing chemical species from the liquid with said media, said chemical species being selected from the group consisting of arsenic, chromium(VI), selenium, boron, phosphates and combinations thereof.
12. The method of claim 1 comprising releasing OH groups or consuming H from the liquid using said pH adjuster material effective to raise the pH of the liquid as it passes said media.
13. The method of claim 12 comprising removing chemical species from the liquid with said media, said chemical species being selected from the group consisting of lead, cadmium, copper, barium, strontium, thallium and combinations thereof.