Peeved about perchlorate
Angela Wheland glossed over ion exchange as a proven treatment option for perchlorate (see “Perchlorate Contamination and Current Treatment Options,” WC&P, pp. 62, February 2003). She mentioned SBA resin (presumably polystyrene), perchlorate selective SBA resins and WBA resins, all of which seem to be difficult to regenerate. It should be noted that Montgomery Watson completed a report project on perchlorate removal for the San Gabriel Basin Watermaster in April 1999.
Quote from the Executive Summary [of that report]: “Polystyrene resins have extremely high capacities for perchlorate, but are very difficult to regenerate. Polyacrylic resins seem to have the right balance between moderate capacity and ease of regeneration.” Two polystyrene resins and two polyacrylic resins were evaluated. Influent concentration of perchlorate was ~90 µg/L. Purolite A-850 Strong Base Type 1 Acrylic Anion Exchange Resin (Cl form) achieved 725 bed volumes treated before perchlorate breakthrough (4 µg/L) occurred. A salt loading rate of 30 lbs/cu ft was consistently sufficient to fully regenerate the A-850 resin. It should be noted that at the time of that study, resin unit cost was $125/cu ft. These resins are now mass produced in China and may be purchased for between $72 and $82 per cu ft (CIF any West Coast port).
Laurence G. D’Alberti – ChE
United Manufacturing International 2000
Red Bluff, Calif.
The author responds: I agree with Mr. D’Alberti’s conclusion that ion exchange is a proven treatment method for perchlorate removal and I appreciate him emphasizing this in his letter. As he points out, polyacrylic resins are easier to regenerate than polysty-renic, but the perchlorate capacities are hardly comparable. The capacities of polystyrenic resins are typically 10-20 times greater than those of the acrylics, with the selective SBA resins potentially reaching capacities that are 100 times higher. Further, one cannot ignore the brine disposal and/or treatment technology issues that accompany the use of any regenerable resin. The economics of these factors—regenerable vs. non-regenerable resin, capacity for perchlorate, brine disposal—are quite complex and certainly cannot be reduced to a cost analysis of resin “mass produced in China.” Instead, I would recommend a thorough assessment of the objectives and limitations of the perchlorate project.
Sybron Chemicals Inc., a Bayer Company
Hanging on the phone
In your May 2002 Ask the Expert section, you had an item entitled “Water Software 101” (see p. 18) and answered in an excellent and unbiased way where these people need to look for software designed for water treatment dealers. Nevada Computer happened to be the first one named and we never had a call from that lady or the one from Canada who wrote you in your August edition (Letters, “Dealer Seeks Software Solution,” p. 8) and I would guess that she did not call the others either. All of us listed in the May article have software that can assist this lady. Nevada Computer just happens to offer the best, in our opinion.
Nevada Computer Systems
Des Moines, Iowa
A fan for 40 years and going
Kudos to your staff on the article, “N-Halamine Technology for Developing Nations: Providing Clean Water to Impoverished Homes,” (D. Duane Dunk and Jeffrey F. Williams, WC&P, pp. 70, March 2003).
Also thank you for your magazine, I have been in water treatment sales, service and installation for 41 years, and owned a chemical business and water treatment business at the same time. Your magazine is great!
At my age to look forward to ANY publication once a month should be unusual. But, like a little kid, I can’t wait till next month after I have read every word.
R.M. Crossan Inc.