Disinfection by-products of chlorine dioxide (chlorite, chlorate, and trihalomethanes): Occurrence in drinking water in Qatar.

The occurrence of chlorine dioxide (ClO 2 ) disinfection by-products (DBPs) in drinking water, namely, chlorite, chlorate, and trihalomethanes (THMs), was investigated. Two-hundred-ninety-four drinking water samples were collected from seven desalination plants (DPs), four reservoirs (R), and eight mosques (M) distributed within various locations in southern and northern Qatar. The ClO 2 concentration levels ranged from 0.38 to <0.02 mg L −1 , with mean values of 0.17, 0.12, and 0.04 mg L −1 for the DPs, Rs, and Ms, respectively. The chlorite levels varied from 13 μg L −1 to 440 μg L −1 , with median values varying from 13 to 230 μg L −1 , 77–320 μg L −1 , and 85–440 μg L −1 for the DPs, Rs, and Ms, respectively. The chlorate levels varied from 11 μg L −1 to 280 μg L −1 , with mean values varying from 36 to 280 μg L −1 , 11–200 μg L −1 , and 11–150 μg L −1 in the DPs, Rs, and Ms, respectively. The average concentration of THMs was 5 μg L −1 , and the maximum value reached 77 μg L −1 However, all of the DBP concentrations fell within the range of the regulatory limits set by GSO 149/2009, the World Health Organization (WHO), and Kahramaa (KM). [ABSTRACT FROM AUTHOR]