Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, P.O. Box 611, 8600 Duebendorf, Switzerland.
Water Res. 2010 Jan;44(2):555-66. doi: 10.1016/j.watres.2009.11.045. Epub 2009 Nov 27.
Chemical oxidation processes have been widely applied to water treatment and may serve as a tool to minimize the release of micropollutants (e.g. pharmaceuticals and endocrine disruptors) from municipal wastewater effluents into the aquatic environment. The potential of several oxidants for the transformation of selected micropollutants such as atenolol, carbamazepine, 17 alpha-ethinylestradiol (EE2), ibuprofen, and sulfamethoxazole was assessed and compared. The oxidants include chlorine, chlorine dioxide, ferrate(VI), and ozone as selective oxidants versus hydroxyl radicals as non-selective oxidant. Second-order rate constants (k) for the reaction of each oxidant show that the selective oxidants react only with some electron-rich organic moieties (ERMs), such as phenols, anilines, olefins, and deprotonated-amines. In contrast, hydroxyl radicals show a nearly diffusion-controlled reactivity with almost all organic moieties (k>or=10(9)M(-1) s(-1)). Due to a competition for oxidants between a target micropollutant and wastewater matrix (i.e. effluent organic matter, EfOM), a higher reaction rate with a target micropollutant does not necessarily translate into more efficient transformation. For example, transformation efficiencies of EE2, a phenolic micropollutant, in a selected wastewater effluent at pH 8 varied only within a factor of 7 among the selective oxidants, even though the corresponding k for the reaction of each selective oxidant with EE2 varied over four orders of magnitude. In addition, for the selective oxidants, the competition disappears rapidly after the ERMs present in EfOM are consumed. In contrast, for hydroxyl radicals, the competition remains practically the same during the entire oxidation. Therefore, for a given oxidant dose, the selective oxidants were more efficient than hydroxyl radicals for transforming ERMs-containing micropollutants, while hydroxyl radicals are capable of transforming micropollutants even without ERMs. Besides EfOM, ammonia, nitrite, and bromide were found to affect the micropollutant transformation efficiency during chlorine or ozone treatment.
化学氧化工艺已广泛应用于水处理，并可能成为减少城市污水中微量污染物（如药物和内分泌干扰物）排放到水生态环境中的一种手段。评估并比较了几种氧化剂（如氯气、二氧化氯、高铁酸盐(VI)和臭氧）对选定的微量污染物（如阿替洛尔、卡马西平、17α-乙炔雌二醇（EE2）、布洛芬和磺胺甲恶唑）的转化能力。氧化剂包括选择性氧化剂氯气、二氧化氯、高铁酸盐(VI)和臭氧，以及非选择性氧化剂羟基自由基。每种氧化剂的反应二级速率常数（k）表明，选择性氧化剂仅与一些富电子有机基团（ERMs）反应，如酚类、苯胺类、烯烃和去质子化的胺类。相比之下，羟基自由基几乎与所有有机基团（k>或=10(9)M(-1) s(-1)）具有扩散控制的反应活性。由于目标微量污染物和废水基质（即出水有机物，EfOM）之间对氧化剂的竞争，与目标微量污染物的更高反应速率不一定转化为更有效的转化。例如，在 pH 值为 8 的选定污水中的 EE2（一种酚类微量污染物）的转化效率，在选择性氧化剂之间仅相差一个数量级，尽管每种选择性氧化剂与 EE2 的反应的相应 k 值相差四个数量级。此外，对于选择性氧化剂，当 EfOM 中存在的 ERMs 被消耗后，竞争迅速消失。相比之下，对于羟基自由基，在整个氧化过程中竞争几乎相同。因此，对于给定的氧化剂剂量，选择性氧化剂在转化含 ERMs 的微量污染物方面比羟基自由基更有效，而羟基自由基即使没有 ERMs 也能够转化微量污染物。除了 EfOM 之外，氨、亚硝酸盐和溴化物在氯或臭氧处理过程中被发现会影响微量污染物的转化效率。
