Chlorine affecting regen beads

[bethw]

Our water treatment people tell us that the chlorine in our city water that supplys our demins (cation, anion units) is killing our newly installed beads. What will chlorine do to these beads? Beth

 

[kenvlach]

Chlorine oxidizes organics, and the resin beads are organic, such as polystrene type.
After particulate filtration, use a filter material such as activated carbon to catch the chlorine.
Most RO membranes also require chlorine removal.

 

[bethw]

We have carbon filters before the units and I am thinking these are "worn out". Is there a life expectency for these things? Do they "wear out"? I suppose I could test for chlorine after these units right?

 

[quark]

Inexpensive way of checking chlorine is to use chemical indicators. Generally, you should maintain a free chlorine level of below 1 ppm. However 0.1 ppm is the best level for IX beds.

It is better if you change activated carbon after every 5 years. Charcoal pores clog over a period of time and steaming the bed is one method to open up the pores.

 

[bimr]

Agree with quarks comments.

Carbon has close to an unlimited capacity for chlorine so it is doubtful that your resin is affected.

Chlorine at the dosages expected will damage the anion resins, not the cation resins.

As Quark pointed out, you must periodically replace the carbon. Otherwise, you take the risk that the carbon will do more harm than good. As an example, microrganisms may grow in carbon and contaminate downstream processes.

 

[GarySCWSVI]

Correction: Chlorine will damage the cation resin also. Test for chlorine residual after the carbon filters. It should not be more than 0.5 ppm after the carbon filter.
Even that will damage the ion exchange resin, but even more so if higher thant that. 1 ppm of chlorine to the ion exchange resin will reduce the resin life by one half. That is for each 1 ppm. Every 1 ppm over 1 ppm will reduce the resin life by another one half.



Gary Schreiber, CWS VI
The Purolite Co.

 

[bimr]

As Gary points out, chlorine at elevated dosages can damage cation resin. The amount of damage depends somewhat on the type of cation resin that you have as well as the concentration of chlorine present.

The minimum recommended chlorine residual in potable water should be at least 0.2 mg/l. At that concentration, the chlorine is probably not going to effect the standard gel type cation resin, but will harm the anion resin as the anion resin is more sensitive to damage. Without knowing the actual chlorine dosage that you have, it is not possible to provide a definitive answer to your question.

Here is a detailed bulletin that may be of assistance to you:

http://www.dow.com/webapps/lit/litorder.asp?filepath=liquidseps/pdfs/noreg/177-01754.pdf&pdf=true

However, if you have a functioning carbon filter preceeding the demineralizer, you do not have to worry about chlorine damage to the resin.