Effect of Bromide and Iodide Ions on the Formation and Speciation of Disinfection Byproducts during Chlorination

Abstract

Two natural waters were fortified with various levels of bromide or iodide ions (0-30 microM) and chlorinated in the laboratory to study the impact of bromide and iodide ions on the formation and speciation of disinfection byproducts. Trihalomethanes (THMs), haloacetic acids (HAAs), total organic halogen (TOX), and its halogen-specific fractions total organic chlorine (TOCl), bromine (TOBr), and iodine (TOI), were measured in this work. The molar yields of THMs and HAAs increased as the initial bromide concentration increased. No significant change in TOX concentration was found for varying bromide concentrations. However, TOX concentrations decreased substantially with increasing initial iodide concentrations. At higher levels of bromide, there was a decreasing level of unknown TOX and unknown TOCl but an increasing level of unknown TOBr. The extent of iodine substitution was much lower than that of bromine substitution when comparing identical initial concentrations because a substantial amount of iodide was oxidized to iodate by chlorine. The tendency toward iodate formation resulted in the unusual situation where higher chlorine doses actually caused reduced levels of iodinated organic byproducts. Quantitative assessment of the results of this study showed a good agreement with kinetic data in the literature.

A comparison of the role of two blue–green algae in THM and HAA formation

“…This is 302 consistent with the theory that bromide is more effectively incorporated into low UV-absorbing, 303 low molecular weight and hydrophilic fractions, since more than 70% of AOM are hydrophilic 304 (Choi et al, 2004;Henderson et al, 2008). With regard to total DBP yield (THM and HAA), 305 however, no significant change was evident in algae samples with a bromide spike compared to 306 those without bromide; this was also reported by an earlier study of chlorination tests carried out on 307 raw water under different bromide levels (Hua et al, 2006). 308…”

Effect of pH on the formation of disinfection byproducts in swimming pool water – Is less THM better?

“…The effect of bromide on DBPs formation in pool water was also investigated, since studies with drinking water have shown increased DBPs levels in the presence of bromide, as well as the formation of Br-based DBPs (Chang et al, 2001;Hua et al, 2006;Hua and Reckhow, 2008). This is due to the oxidation of Br -by the HOCl, forming of hypobromous acid (HOBr) (White, 1992).…”

Effect of medium-pressure UV-lamp treatment on disinfection by-products in chlorinated seawater swimming pool waters

“…However, bromine incorporation was expected to be unaffected by UV treatment followed by the chlorination of water from seawater pools, due to the presence of high bromide levels of seawater in this study. Furthermore, previous studies with drinking water have shown increased DBP levels in the presence of bromide, as well as the formation of brominated DBPs (Chang et al, 2001;Hua et al, 2006), which is likely due to the oxidation of bromide by hypochlorous acid to form hypobromous acid (White, 1992), the latter of which reacts with the dissolved organic matter and forms brominated DBPs. A higher level of brominated DBPs has been reported by several studies for pools filled with seawater (Chowdhury et al, 2014;Manasfi et al, 2016).…”