Chlorine Demands of Amino Acids and Amino Sugars in Water

概要

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Nitrogenous compounds are ubiquitous in drinking water sources and they increase the chlorine demand of water, shift the breaking point, and also cause strong odors. The present study was performed to investigate the chlorine demands of selected amino acids and amino sugars in water. The results indicated that the chlorine demands of the precursors were in the order: aromatic amino acids (except histidine) › S-amino acids › non-S-amino acids and amino sugars. Aromatic amino acids were expected to have the highest chlorine demand due to chlorine substitution in both the aliphatic and aromatic parts of these molecules. However, the chlorine demand of histidine was threefold lower than those reported previously, which may be attributed to the experimental conditions or shorter contact time used in this study. The chlorine demands of most compounds did not show marked differences at contact times of 15 - 96 h, although some of the nitrogenous organic compounds showed an increasing trend in chlorine demand with time when our 24 h study was compared with previous studies conducted at 72 and 96 h. Chlorine demand in 24 h showed a good correlation with predicted data. Kinetic studies are required to understand how fast the precursors can react with chlorine in typical water treatment contact times and chlorine doses. The information presented here will be useful in controlling disinfection byproducts.