Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600 Dübendorf, Switzerland; School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600 Dübendorf, Switzerland; School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Water Res. 2024 Sep 1;261:121917. doi: 10.1016/j.watres.2024.121917. Epub 2024 Jun 10.
Ozonation is used worldwide for drinking water disinfection and increasingly also for micropollutant abatement from wastewater. Identification of transformation products formed during the ozonation of micropollutants is challenging due to several factors including (i) the reactions of both oxidants, ozone and hydroxyl radicals with the micropollutants, as well as with intermediate transformation products, (ii) effects of the water matrix on the ozone and hydroxyl radical chemistry and (iii) the generation of oxidation by-products. In this study, a simple approach to achieve realistic ozonation conditions in the absence of dissolved organic matter has been developed. It is based on composing synthetic water matrices with low-molecular-weight scavenger compounds (phenol, methanol, acetate, and carbonate) that mimic the chemical interactions of ozone and hydroxyl radicals with real water matrices. Synthetic waters composed of only four low-molecular-weight compounds successfully replicated two lake waters and two secondary wastewater effluents, matching instantaneous ozone demand, ozone and hydroxyl radical exposures in the initial phase, as well as the ozone evolution in the second phase of the ozonation process. The synthetic water matrices also reproduced the effects of temperature and pH changes observed in real waters. The abatement of two micropollutants, bezafibrate and atrazine, and the formation of the corresponding transformation products during ozonation were in agreement for synthetic and real waters. Furthermore, the kinetics and extent of bromate formation during ozonation in synthetic water were comparable to real lake water and wastewater. This supports the robustness of the proposed approach because bromate formation is very sensitive to the interplay of ozone and hydroxyl radicals. Furthermore, with the novel reaction system, a significant effect of hydroxyl radicals scavenging by carbonate on bromate formation was demonstrated. Overall, the herein-developed approach based on synthetic water matrices allows to perform realistic ozonation studies including both oxidants, ozone and hydroxyl radicals, without the constraints of using dissolved organic matter.
臭氧氧化被广泛用于饮用水消毒，并越来越多地用于去除废水中的微量污染物。由于以下几个因素，鉴定微量污染物在臭氧氧化过程中形成的转化产物具有挑战性：(i) 氧化剂臭氧和羟基自由基与微量污染物以及中间转化产物的反应；(ii) 水基质对臭氧和羟基自由基化学的影响；(iii) 氧化副产物的生成。在这项研究中，开发了一种简单的方法，可在不存在溶解有机物的情况下实现实际的臭氧氧化条件。该方法基于用低分子量猝灭化合物（苯酚、甲醇、乙酸盐和碳酸盐）组成合成水基质，这些化合物模拟了臭氧和羟基自由基与真实水基质的化学相互作用。由仅四种低分子量化合物组成的合成水成功复制了两种湖水和两种二级废水，匹配瞬时臭氧需求、初始阶段的臭氧和羟基自由基暴露以及臭氧氧化过程的第二阶段的臭氧演化。合成水基质还再现了实际水中观察到的温度和 pH 值变化的影响。两种微量污染物（贝扎贝特和莠去津）在臭氧氧化过程中的去除以及相应转化产物的形成在合成水和实际水中是一致的。此外，在合成水中，溴酸盐形成的动力学和程度与实际湖水和废水相当。这支持了所提出方法的稳健性，因为溴酸盐的形成对臭氧和羟基自由基的相互作用非常敏感。此外，在新的反应体系中，证明了碳酸盐对羟基自由基的猝灭对溴酸盐形成有显著影响。总的来说，基于合成水基质的这种新方法允许进行包括臭氧和羟基自由基在内的实际臭氧氧化研究，而无需使用溶解有机物的限制。
