While ozonation is considered an efficient treatment to eliminate trace organic compounds (TrOCs) from secondary wastewater effluents, the presence and persistence of transformation products (TPs) resulting from ozonation of TrOCs is a major concern that should be assessed prior to effluent discharge to the environment. Venlafaxine (VLX), an environmentally relevant tertiary amine-containing TrOC, was chosen as the model for this study. TP analysis confirmed that the lone electron pair of the non-protonated amine are the predominant site of oxidant attack, and therefore strongly affected by pH value and VLX speciation. N-oxide VLX (NOV), the primary ozone-induced TP, was formed and degraded simultaneously during ozonation of VLX-containing secondary effluent and reached a maximum yield of 0.44 to 0.85 (NOV-to-VLX0 ratio), depending on pH and hydroxyl (OH) radical presence. Rate constants for the reaction of NOV with ozone (3.1×102M-1s-1) and OH radicals (5.3×109M-1s-1) were determined. A simple kinetic model was developed to fit the kinetics of formation and degradation of NOV during ozonation in secondary effluents, based on a known ozone-reaction kinetic equation. The biodegradability of NOV (degradation rate of 39%) was significantly lower than that of the parent compound (VLX, 92%) after 71days, as evaluated by modified Zahn-Wellens tests, suggesting that N-oxide products are not better removed than the parent compound in a simulated biological post-treatment, which may even result in partial reformation of the parent compound. Lessons learned from this study were supported by a pilot-scale demonstration at the Shafdan wastewater-treatment plant, confirming the presence of NOV after ozonation and its persistence in biological post-treatment. Removal of such persistent TP will require higher dosages or promotion of OH-radicals during ozonation. Nevertheless, further assessment of the toxicity of persistent TPs relative to the parent compound is needed for complete evaluation of concerned TPs.

中文翻译：

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臭氧化和生物后处理过程中N-氧化物文拉法辛的形成和降解。

尽管臭氧处理被认为是消除次级废水中痕量有机化合物（TrOCs）的有效方法，但由于TrOCs臭氧化所产生的转化产物（TPs）的存在和持久性是主要问题，应在将废水排放到环境之前进行评估。文拉法辛（VLX）是一种与环境有关的含叔胺的TrOC，被选作该研究的模型。TP分析证实，非质子化胺的孤电子对是氧化剂攻击的主要部位，因此受到pH值和VLX形态的强烈影响。N-氧化物VLX（NOV）是主要的臭氧诱导的TP，在含VLX的次级废水进行臭氧化过程中同时形成和降解，并达到0.44至0.85的最大产率（NOV与VLX0的比率），取决于pH值和羟基（OH）自由基的存在。确定了NOV与臭氧（3.1×102M-1s-1）和OH自由基（5.3×109M-1s-1）反应的速率常数。基于已知的臭氧反应动力学方程式，开发了一个简单的动力学模型来拟合臭氧在次级废水中臭氧化过程中NOV形成和降解的动力学。根据改良的Zahn-Wellens试验评估，71天后，NOV的生物降解性（降解率39％）显着低于母体化合物（VLX，92％），这表明N-氧化物产物的去除能力并不比NOV更好。模拟生物后处理中的母体化合物，甚至可能导致母体化合物部分重整。从这项研究中吸取的教训得到了Shafdan废水处理厂的试点示范的支持，证实臭氧化后存在NOV及其在生物后处理中的持久性。去除此类持久性TP将需要更高的剂量或在臭氧化过程中促进OH自由基的产生。尽管如此，仍需要进一步评估持久性TP相对于母体化合物的毒性，以完整评估相关TP。