Odors arising from ammonia and amino acids with chlorine during water treatment

Odor produced by breakpoint chlorination in a drinking water purification p rocess was researched. Ammonia and six amino acids (glycine, alanine, valin e, leucine, arginine, proline) were chlorinated and production of odor and its change were investigated. An intense odor which was different to the od or of residual free chlorine was detected after the chlorination of ammonia . The production of the odor was affected by pH and chlorine dose rate. Whi le the intense odor was not produced in the breakpoint chlorination at pH 8 .3, a weak odor before the breakpoint and the intense odor after the breakp oint were produced at pH 6.5. At pH 3.0, the intense odor was detected even in a sample of low chlorine dose rate. An identification of the intense od or substance was done using a gas chromatograph-mass spectrometer and trich loramine or a dimer of dichloramine was suspected as the odor causing subst ance. In chlorination of the six amino acids, the intense odor and its chan ge were different according to each amino acid. Production of chlorinated i ntermediate and final products which had a different odor were suspected as one of the reasons. (C) 1999 IAWQ Published by Elsevier Science Ltd. All r ights reserved.