Full Description

In order to comply with the maximum contaminant levels for trihalomethanes (THMs)and haloacetic acids (HAAs), many utilities are utilizing alternative disinfectants, such as chlorinedioxide (ClOsub2/sub) and chloramines (NHsub2/subCl). The use of ClOsub2/sub in bench- and demonstration-scaletests was found to produce no THMs or trihalogenated HAAs, or only trace amounts, butit did form low levels of dihalogenated HAAs (DXAAs). In the presence of bromide, brominatedDXAA species formed. Post-chloramination did not stop THM formation in watershigh in total organic carbon and/or bromide. THM formation in the presence of NHsub2/subCl was ofthe order of 20 percent of the amount that would have formed in the presence of free chlorine.Because ClOsub2/sub is a strong radical oxidant, it can form oxidation byproducts similar tothose formed by ozone (carboxylic acids, aldoketoacids, aldehydes), but ClOsub2/sub typically formsbyproducts at lower levels (on a weight basis) than ozone. The formation of carboxylic acids,especially oxalate, increased with increasing ClOsub2/sub demand. Secondary byproducts from postdisinfection(e.g., haloacetaldehydes) also formed. Includes 22 references, table, figures.

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Edition: Vol. - No. Published: 11/02/2003 Number of Pages: 15File Size: 1 file , 380 KB