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ABSTRACT: The effects of the concentration of dissolved total organic carbon (TOC), the TOC/Br− ratio, bromide ion levels, the chlorine to ammonia-N ratio (Cl:N), the monochloramine dose and the chlorine dose on the formation
of trihalomethanes (THMs) (including chloroform, bromodichloromethane, chlorodibromomethane, and bromoform) from chlorination
were investigated using aqueous humic acid (HA) solutions. The profile of the chloramine decay was also studied under various
bromide ion concentrations. Monochloramine decayed in the presence of organic material and bromide ions. The percentage of
chloroform and brominated THMs varied according to the TOC/Br− ratio. Total THMs (TTHMs) formation increased from 112 to 190 μg/L with the increase concentrations of bromide ions from
0.67 to 6.72 mg/L, but the chlorine-substituted THMs were replaced by bromine-substituted THMs. A strong linear correlation
was obtained between the monochloramine dose and the formation of THMs for Cl:N ratios of 3:1 and 5:1. These ratios had a
distinct effect on the formation of chloroform but had little impact on the formation of bromodichloromethane or chlorodibromomethane.
The presence of bromide ions increased the rate of monochloramine decay.
Key wordsTrihalomethanes (THMs)-Humic acid (HA)-Bromide-Monochloramine
Journal of Zhejiang University - Science A: Applied Physics & Engineering 11(8):606-612. · 0.53 Impact Factor