Taste and Timing

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Science  22 Dec 2006:
Vol. 314, Issue 5807, pp. 1842
DOI: 10.1126/science.314.5807.1842b

Modern water treatment protocols have gone a long way toward the efficient elimination of toxic contaminants in municipal supplies. However, certain benign impurities may remain and give rise to unpleasant tastes or odors. One challenge in adopting a general strategy for treating such “T&O” compounds is their varying proportions in different water sources. Effective remediation thus requires detailed knowledge of the distinct chemistry of each substance.

Toward this end, Peter and von Gunten present a systematic study of the oxidation kinetics of 11 common organic T&O contaminants by both ozone and hydroxyl radicals. The targets, spanning a variety of alcohols, aldehydes, ketones, and ethers, were treated individually with the oxidants in ultrapure water, and measured rate constants were then used to predict the degradation kinetics observed in spiked samples of natural water from two different lakes. In general, the predictions and measurements showed strong agreement. Five of the compounds were very efficiently oxidized by ozone, with rate constants of ∼105 M−1s−1. Trihaloanisoles proved the most resistant to preliminary ozonation but were rapidly degraded by hydroxyl radicals. The authors note that hydroxyl radical protocols would need to be applied carefully to avoid excessive production of toxic bromate ions from residual aqueous bromide salts. — JSY

Environ. Sci. Technol. 10.1021/es061687b (2006).

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