Pre-oxidation is often used before disinfection with chlorine to decrease the reactivity of the water matrix and mitigate the formation of regulated disinfection byproducts (DBPs). This study provides insights on the impact of oxidative pre-treatment with chlorine dioxide (ClO₂), ozone (O₃), ferrate (Fe(VI)) and permanganate (Mn(VII)) on Suwannee River Natural Organic Matter (SRNOM) properties characterized by the UV absorbance at 254 nm (UV₂₅₄) and the electron donating capacity (EDC). Changes in NOM reactivity and abatement of DBP precursors are also assessed. The impact of pre-oxidants (based on molar concentration) on UV₂₅₄ abatement ranked in the order O₃ > Mn(VII) > Fe(VI)/ClO₂, while the efficiency of pre-oxidation on EDC abatement followed the order Mn(VII) > ClO₂ > Fe(VI) > O₃ and two phases were observed. At low specific ClO₂, Fe(VI) and Mn(VII) doses corresponding to < 50% EDC abatement, a limited relative abatement of UV₂₅₄ compared to the EDC was observed (∼ 8% EDC abatement per 1% UV₂₅₄ abatement). This suggests the oxidation of phenolic-type moieties to quinone-type moieties which absorb UV₂₅₄ and don't contribute to EDC. At higher oxidant doses (> 50% EDC abatement), a similar abatement of EDC and UV₂₅₄ (∼ 0.9–1.2% EDC abatement per 1% UV₂₅₄ abatement) suggested aromatic ring cleavage. In comparison to the other oxidants, O₃ abated the relative UV₂₅₄ more effectively, due to a more efficient cleavage of aromatic rings. For a pre-oxidation with Mn(VII), ClO₂ and Fe(VI), similar correlations between the EDC abatement and the chlorine demand or the adsorbable organic halide (AOX) formation were obtained. In contrast, O₃ pre-treatment led to a lower chlorine demand and AOX formation for equivalent EDC abatement. For all oxidants_, trihalomethane formation was poorly correlated with both EDC and UV_254. The EDC abatement was found to be a pre-oxidant-independent surrogate for haloacetonitrile formation. These results emphasize the benefits of combining EDC and UV₂₅₄ measurement to understand and monitor oxidant-induced changes of NOM and assessing DBP formation.

在用氯气消毒之前，经常使用预氧化以降低水基质的反应性并减轻调节消毒副产物（DBP）的形成。这项研究提供了关于Suwannee河天然有机物（SRNOM）氧化预处理与二氧化氯（ClO ₂），臭氧（O ₃），高铁酸盐（Fe（VI））和高锰酸盐（Mn（VII））的见解。特性以254 nm的紫外线吸收率（UV ₂₅₄）和电子给体容量（EDC）为特征。还评估了NOM反应性的变化和DBP前体的减少。预氧化剂（基于摩尔浓度）对减少UV ₂₅₄的影响的顺序为O ₃ > Mn（VII）> Fe（VI）/ ClO ₂，而在EDC消除上的预氧化效率遵循Mn（VII）> ClO ₂ > Fe（VI）> O ₃的顺序，并且观察到两相。在较低的特定ClO ₂，Fe（VI）和Mn（VII）剂量下，相当于<50％EDC消除，与EDC相比，UV _254的相对消除相对有限（每1％UV ₂₅₄消除约8％的EDC消除） 。这表明酚醛型部分被氧化为醌型部分，该部分吸收紫外线₂₅₄且对EDC无贡献。在较高的氧化剂剂量下（> 50％的EDC消除），对EDC和UV _254的消除类似（每1％的UV ₂₅₄约0.9-1.2％的EDC消除）减少）建议芳香环裂解。与其他氧化剂相比，由于芳环的裂解效率更高，O _3可以更有效地减少相对紫外线₂₅₄。对于用Mn（VII），ClO ₂和Fe（VI）进行的预氧化，获得了EDC减少与氯需求或可吸附有机卤化物（AOX）形成之间的相似相关性。相比之下，O ₃预处理导致较低的氯需求量和与EDC等效的AOX形成。对于所有氧化剂_，三卤甲烷的形成与EDC和UV ₂₅₄均不很相关_。发现EDC消除是卤代乙腈形成的一种独立于氧化剂的替代物。这些结果强调了结合使用EDC和UV ₂₅₄测量来了解和监视氧化剂引起的NOM变化并评估DBP形成的好处。