Comparison of the impact of ozone, chlorine dioxide, ferrate and permanganate pre-oxidation on organic disinfection byproduct formation during post-chlorination

Abstract

Pre-oxidation is commonly used to mitigate the formation of byproducts during post-disinfection.

Characterization and drivers of haloacetic acids in New York State

“…The positive signal seen for UV use is likely a promotive effect caused by the differences in NOM speciation, TOC concentrations, and the use of chlorinebased disinfectants. Finally, the positive correlation between permanganate and HAA6Br and HAA4 is consistent with research showing that pre-oxidation with permanganate can increase the level of brominated DBPs (Rougé et al, 2020;Wang et al, 2020). This could be explained by the decrease in reactive sites of the NOM after pre-oxidation with permanganate, favoring the rapid bromination of those sites (Rougé et al, 2020).…”

“…HAA4 concentrations tend to rise with permanganate and decline with the use of gaseous chlorine, hypochlorite, and UV. As stated previously, pre‐oxidation with permanganate can increase the level of brominated DBPs (Rougé et al, 2020; Wang et al, 2020), possibly because of a decline in reactive sites of the NOM after pre‐oxidation that favors rapid bromination of those sites (Rougé et al, 2020). This could explain the positive effect seen in Table 3.…”

Influence of bromide and iodide on the formation of disinfection by-products in drinking water treatment

“…It has recently been showed that the additivity of individual toxicities was representative of the CHO cell cytotoxicity associated with known DBPs in real disinfected waters [55]. Several studies reported the importance of Br-and/or I-DBPs over Cl-DBPs using this approach [55][56][57][58][59][60]. I-DBPs exhibiting particularly high toxicity, despite their usually much lower concentration in treated waters may be important toxicity drivers.…”

“…These oxidants have been applied successfully to reduce the formation of regulated DBPs during post-chlorination by reducing the reactivity of the DOM. However, in some cases, an increase or a similar formation of Br-DBPs has been observed[60,100,101]. Applying O3, KMnO4, ClO2 or Fe(VI) as a pre-treatment oxidizes reactive moieties in the DOM, which renders them typically less reactive towards chlorine or bromine in post-disinfection, thereby affecting the subsequent formation of Br-DBPs.…”

“…However, in many cases the concentration of Br-DBPs increased after pre-oxidation. The pre-oxidant dose should be optimized to decrease the reactivity of the matrix while controlling the toxicity induced by the formation of brominated DBPs, notably brominated HANs[60].…”