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Experiments were carried out to confirm the presence of chlorate ion (ClO3-) in the treated water of utilities that use hypochlorination. Sixteen commercially produced, concentrated liquid hypochlorite feedstocks were analyzed for ClO3-, and levels as high as 158 g percent ClO3- relative to hypochlorite ion were measured. Finished-water samples from the utilities surveyed contained as much as 0.30 mg ClO3-/L, primarily the result of decomposition of the liquid hypochlorite feedstocks. Although both dilution and lower temperatures can be effective in minimizing ClO3- formation, it was observed that diluting the initial liquid hypochlorite concentration by a factor of 2 is more effective than decreasing the temperature from 24 to 10C. A methodology is proposed that predicts the dilution or temperature reduction (or both) required to avoid significant ClO3- formation in the feedstock solutions. Includes 27 references, tables, figures.

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Edition: Vol. 85 - No. 9 Published: 09/01/1993 Number of Pages: 9 File Size: 1 file , 1.5 MB