This study was to compare the formation of iodinated trihalomethanes (I-THMs) when iodide-containing raw waters are oxidized by chlorine, chlorine dioxide (ClO2) and potassium permanganate (KMnO4) at different oxidant concentrations, reaction times, pHs, initial iodide concentrations and bromide to iodine mass ratios. Among the 6 investigated I-THMs, iodoform was the major species formed during the oxidation of chlorine, ClO2 and KMnO4. When oxidant concentration increased from 0.1 to 3.0 mg/L, the formation of I-THMs increased and then decreased for chlorine and ClO2, but kept increasing for KMnO4. As the reaction time went by, I-THM concentration increased to a plateau within 10 h (ClO2 within only 1 h, especially) for all the three disinfectants. I-THM formation gradually increased from pH 3 to 9 and remained stable at high pHs for chlorine; however, for ClO2 and KMnO4 the highest I-THM formation showed at pH 7 and 7.5, respectively. As initial iodide concentration increased, the total amount and species of I-THMs increased for the 3 disinfectants. Iodide played a more important role than bromide in the formation of brominated I-THMs.

Comparison of iodinated trihalomethanes formation from chlorine, chlorine dioxide, and potassium permanganate oxidation processes

248th National Meeting (2014)

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