Posted By Sam Sneed on 7/17/2009 at 4:49:13 PM
Can DI (deionization) resin be regenerated with salt? Do you lose anything by doing so? Does the water have to be softened first?


Jim Wark: 7/17/2009 5:40:17 PM
DI resin, to work in removing both cations and ions properly, cannot be regenerated properly with only salt. There are many online resin manufacturers who will give you correct information on regeneration right on their Web sites.

DI resin depends on its makeup, is more selective to different salts and metals, and most often needs multiple regenerants to clean it properly.

Unlike softeners, DI resins have the ability to reduce cations (as a softener) like calcium and magnesium, as well as anions (such as chloride and sulfate).

The regenerants are often too hazardous for economical use by untrained individuals, so most have DI tanks which are leased and cleaned by the leasing company or taken to plants which do this service for them.

R. Ross Derksen: 7/17/2009 7:49:18 PM
You can, of course, regenerate DI resin with salt, but you won”t get DI water.

The cation resin will become a softening resin and will exchange other cations for sodium. If you regenerate the anion resin with salt you will exchange the anions for chloride.

So if you regenerate both resins with salt, you will remove the cations and anions and add sodium chloride (salt).

With DI, you want to replace the cations with hydrogen (H+) ions, so you have to regenerate the cation resin with an acid. You want to replace the anions with hydroxides (OH), so you need to regenerate the anion resin with a base. In this case, you have removed the cations and anions present and replaced them with water (H2O).

Rex Johnson: 7/17/2009 9:13:49 PM
The DI regeneration process requires the use of very hazardous materials and must be strictly monitored.

No amateur should ever try it without a lot of help from a very experienced water treatment specialist who knows what he or she is doing.

Gary Schreiber, CWS VI: 7/17/2009 9:35:34 PM
Sam, the answers you have been given so far are correct. I have sent you a private e-mail asking you to call me. I will be happy to help.

Russ Knight: 7/18/2009 4:22:23 PM
If you add sodium chloride (salt) to the water, wouldn”t that make it taste salty?

Gary Schreiber, CWS VI: 7/18/2009 4:49:47 PM
That depends upon the TDS (total dissolved solids) of the raw water. If the TDS is more than 250 ppm, most likely it would. The higher the TDS, the more salty the taste.

Russ Knight: 7/19/2009 5:35:14 PM
Then wouldn”t using ion exchange to remove iron, then tannin do the same thing?

Gary Schreiber, CWS VI: 7/19/2009 7:25:04 PM
I”ll say it again: That depends upon the TDS of the raw water ….

Taoward Lee: 7/21/2009 5:53:52 PM
Make sure that deionization is used for industrial purposes only.

No residential use. There is no way to ensure the safety of a residential user. (Unless it is for yourself and you are properly trained. Remember, any error could put acid or caustic in your water system.)

Be safe!!!