Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 100085, Beijing, China; Delft University of Technology, Department of Water Management, PO Box 5048, 2600GA, Delft, the Netherlands; University of the Chinese Academy of Sciences, 100019, Beijing, China.
Delft University of Technology, Department of Water Management, PO Box 5048, 2600GA, Delft, the Netherlands; Berliner Wasserbetriebe, Motardstr. 35, 13629, Berlin, Germany.
Water Res. 2020 Apr 15;173:115574. doi: 10.1016/j.watres.2020.115574. Epub 2020 Feb 4.
Though the ozone-activated carbon process has been widely applied for drinking water purification, little is known about how ozone-modified natural organic matter (NOM) competes with micropollutants in activated carbon adsorption. In this study, three natural waters and one synthetic water (standard humics solution) with highly heterogeneous NOM compositions were employed to investigate the interference of ozonated NOM with the adsorption of 2-methylisoborneol (MIB). Analysis using liquid chromatography with online carbon and UV detection (LC-OCD-UVD) revealed that ozonation led to various disintegration patterns of macromolecules in NOM, and UV absorbance was reduced markedly for nearly all NOM fractions. Powdered activated carbon (PAC) adsorption experiments showed that increasing ozone consumption coincided with reducing NOM competition against MIB in the three natural waters, as expressed by the fitted initial concentrations of the equivalent background compound (c). In the synthetic water, in contrast, competition increased under low/moderate specific ozone consumptions and then decreased with further elevation of ozone consumptions. Regarding the significance on affecting ozonated NOM interference, aromaticity reduction outweighed formation of low molecular weight (LMW) organics in most cases, enhancing MIB adsorption capacity. However, disintegration of the humics fraction with larger molecular weight (1,103 g/mol, as compared to 546-697 g/mol in three natural waters) into smaller, more competitive fractions caused the observed initial deteriorated MIB adsorption in synthetic water. A superior correlation between c and the UV absorbance of LMW organics (R = 0.93) over concentrations of LMW organics underlined the importance of the aromatic properties in competitive adsorption projection for ozone pretreated natural waters. Furthermore, the change of relative concentration of UV absorbing compounds during ozonation could help estimate the decrease of c, which could be a promising tool for waterworks to adjust PAC doses for MIB removal in ozonated waters.
尽管臭氧-活性炭工艺已广泛应用于饮用水净化，但对于臭氧改性天然有机物 (NOM) 如何与微污染物在活性炭吸附中竞争知之甚少。本研究采用三种天然水和一种合成水（标准腐殖质溶液），具有高度异质的 NOM 组成，以研究臭氧化 NOM 对 2-甲基异莰醇 (MIB) 吸附的干扰。使用带有在线碳和紫外检测的液相色谱 (LC-OCD-UVD) 分析表明，臭氧化导致 NOM 中大分子的各种解体模式，并且几乎所有 NOM 部分的紫外吸光度都明显降低。粉末活性炭 (PAC) 吸附实验表明，随着臭氧消耗的增加，三种天然水中的 NOM 对 MIB 的竞争作用降低，这可以通过拟合等效背景化合物 (c) 的初始浓度来表示。相比之下，在合成水中，在低/中等特定臭氧消耗下，竞争作用增加，然后随着臭氧消耗的进一步增加而降低。关于影响臭氧化 NOM 干扰的重要性，芳香性降低在大多数情况下超过了低分子量 (LMW) 有机物的形成，从而增强了 MIB 的吸附能力。然而，将分子量较大的腐殖质部分（1103 g/mol，与三种天然水中的 546-697 g/mol 相比）分解成更小、更具竞争力的部分，导致在合成水中观察到初始 MIB 吸附恶化。c 与 LMW 有机物的紫外吸光度之间的良好相关性（R=0.93）超过了 LMW 有机物浓度，突出了芳香性在臭氧预处理天然水中竞争吸附预测中的重要性。此外，臭氧化过程中紫外吸收化合物的相对浓度变化可以帮助估计 c 的减少，这可能是水厂在臭氧处理水中调整 PAC 剂量以去除 MIB 的有前途的工具。
