Dear Editor,

I’m writing in response to the article, “The Removal of Arsenic from Potable Water” by Frank Baumann, P.E. in the May 2006 issue of WC&P magazine. I applaud Mr. Baumann for his contribution in providing a necessary review and summary of available arsenic removal technologies. However, his article also contains several inaccuracies that should really be corrected. The choice of treatment technologies for any contaminant is dependent on having a clear understanding of the chemical environment of the water. Inaccurate technical language can sometimes paint an incorrect chemical picture.

First of all, the correct definition of ‘valence’ in chemistry is: a) the outermost electron shell of an atom or ion when using the term ‘valence shell’ or b) the number of electrons in the outermost shell of an atom or ion that can be involved in a chemical reaction when using the term ‘valence electrons’. When the term ‘valence’ is used on its own, such as when talking about the valence of an atom, the word “electrons” is assumed. “Valence” is not, as Mr. Baumann writes, “…the combining power of an element with other elements or compounds”, however, it can be indicative of the element’s reactivity or “…combining power….”

Second, in terms of chemical nomenclature, arsenate is not (As5+) any more than sulfate is (S6+). Arsenate is AsO43-, just as sulfate is SO42-. Arsenate does contain pentavalent arsenic (As5+) just as sulfate contains hexavalent sulfur. Likewise, arsenite is AsHO32- and contains trivalent arsenic (As3+). Furthermore, arsine gas is AsH3 and not (As3-). An alternative phrasing would be that arsine gas contains arsenic in the negative three (-3) oxidation state. Had the author pointed this out in his initial definitions, the remaining shorthand throughout the article would be, for the most part, acceptable as is. There are other instances in the article where the use of arsenate/arsenite would be more appropriate as it would provide a clearer picture of the potential chemical reactions.

I realize that these nomenclature errors result from an accepted shorthand throughout the industry. However, any well-written article would define shorthand terms at their first usage for clarity. Also, this industry requires an understanding of chemistry for accurate work, which makes the use of correct chemical notations all the more critical.

Continuing, in discussing the process by which arsenic is metabolized, the author writes that arsenite is “…methylated to arsenate”. This is an incorrect statement. The methylation reaction results in monomethyl arsonate, MMA or CH3AsO(OH)2, which, chemically, is significantly different from arsenate, AsO43-.

In discussing ion exchange, the author makes the statement that ion exchange is a process “…capable of complete removal of all dissolved mater….” This is untrue. Ion exchange is capable of removing dissolved ionic matter, yes. However, not all dissolved matter is ionic.

Further on, the author discusses the regeneration of activated alumina after it has adsorbed various species present in water. The author states that, “…fluoride, selenium, some organic molecules and some trace heavy metal ions…are also completely regenerated along with arsenic.” This is also an incorrect statement as it is the alumina that is regenerated, not the adsorbed material.

Again, kudos to Mr. Baumann and to WC&P for representing the necessary and timely topic of arsenic removal technologies. I thought it was a good summary, but was marred by some inaccurate technical language. It would serve the industry to be more mindful of this.


Tanya Lubner, Ph.D.
Director of Education & Certification
Water Quality Association

Dear WC&P;

After reading (K. Smith’s) April Viewpoint comments concerning April Fools’ Day water treatment follies and then going over “A Cooler Option of Canadian Cooling Towers” by E. James Dart, I wonder if anyone really appreciates that the, “electrostatic physical water conditioning device” discussed in the article is in the same class as vibrationally charged water.

There are many research and case history reports on such devices; to date I have yet to see one that shows such devices work as claimed. A good one to look over is by the U.S. Army Corps of Engineers, Demonstration and Evaluation of Magnetic Descalers available at or my own recent paper at the International Water Conference, Non-Chemical Devices: Thirty Years of Myth Busting IWC-04-22, available at

I would suggest that you contact our trade organization, the Association of Water Technologies ( prior to publication of any future article on ‘magic’ industrial water treatment technology so as not to ‘fool’ your readers. Our 400+ members have opinions somewhat different than those expressed in the article.


Timothy Keister, CWT FAIC
Chief Chemist/President
ProChemTech International, Inc.
Brockway, Pa.


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