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

The occurrence of chlorine dioxide (ClO2) 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 ClO2 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 mu g L-1 to 440 mu g L-1, with median values varying from 13 to 230 mu g L-1, 77-320 mu g L-1, and 85-440 mu g L-1 for the DPs, Rs, and Ms, respectively. The chlorate levels varied from 11 mu g L-1 to 280 mu g L-1, with mean values varying from 36 to 280 mu g L-1, 11-200 mu L-1, and 11-150 mu g L-1 in the DPs, Rs, and Ms, respectively. The average concentration of THMs was 5 mu g L-1, and the maximum value reached 77 mu g 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). (C) 2016 Elsevier Ltd. All rights reserved.