Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland.
Environ Sci Technol. 2009 Oct 15;43(20):7862-9. doi: 10.1021/es9014629.
The removal efficiency for 220 micropollutants was studied at the scale of a municipal wastewater treatment plant (WWTP) upgraded with post-ozonation followed by sand filtration. During post-ozonation, compounds with activated aromatic moieties, amine functions, or double bonds such as sulfamethoxazole, diclofenac, or carbamazepine with second-order rate constants for the reaction with ozone >10(4) M(-1) s(-1) at pH 7 (fast-reacting) were eliminated to concentrations below the detection limit for an ozone dose of 0.47 g O3 g(-1) dissolved organic carbon (DOC). Compounds more resistant to oxidation by ozone such as atenolol and benzotriazole were increasingly eliminated with increasing ozone doses, resulting in >85% removal for a medium ozone dose (approximately 0.6 g O3 g(-1) DOC). Only a few micropollutants such as some X-ray contrast media and triazine herbicides with second-order rate constants <10(2) M(-1) s(-1) (slowly reacting) persisted to a large extent. With a medium ozone dose, only 11 micropollutants of 55 detected in the secondary effluent were found at >100 ng L(-1). The combination of reaction kinetics and reactor hydraulics, based on laboratory-and full-scale data, enabled a quantification of the results by model calculations. This conceptual approach allows a direct upscaling from laboratory- to full-scale systems and can be applied to other similar systems. The carcinogenic by-products N-nitrosodimethylamine (NDMA) (< or =14 ng L(-1)) and bromate (<10 microg L(-1)) were produced during ozonation, however their concentrations were below or in the range of the drinking water standards. Furthermore, it could be demonstrated that biological sand filtration is an efficient additional barrier for the elimination of biodegradable compounds formed during ozonation such as NDMA. The energy requirement for the additional post-ozonation step is about 0.035 kWh m(-3), which corresponds to 12% of a typical medium-sized nutrient removal plant (5 g DOC m(-3)).
研究了在采用后臭氧氧化和砂滤工艺升级的城市污水处理厂（WWTP）中对 220 种微量污染物的去除效率。在后臭氧氧化过程中，具有活化芳香基团、胺官能团或双键的化合物（如磺胺甲恶唑、双氯芬酸或卡马西平）与臭氧的二级反应速率常数 >10(4) M(-1) s(-1)，在 pH 7 下（快速反应），被消除至臭氧剂量为 0.47 g O3 g(-1)溶解有机碳（DOC）以下的检测限以下。臭氧氧化反应性更高的化合物（如阿替洛尔和苯并三唑）随着臭氧剂量的增加而逐渐被消除，中等臭氧剂量（约 0.6 g O3 g(-1) DOC）的去除率>85%。只有少数微量污染物（如一些 X 射线造影剂和三嗪除草剂），它们的二级反应速率常数<10(2) M(-1) s(-1)（缓慢反应），在很大程度上仍存在。采用中等臭氧剂量，在二级出水中检测到的 55 种微量污染物中，仅有 11 种浓度大于 100 ng L(-1)。基于实验室和全尺度数据的反应动力学和反应器水力特性的组合，通过模型计算对结果进行了量化。这种概念方法允许从实验室到全尺度系统的直接扩展，并可应用于其他类似系统。在臭氧氧化过程中产生了致癌副产物 N-亚硝基二甲胺（NDMA）（<或=14 ng L(-1)）和溴酸盐（<10 microg L(-1)），但它们的浓度低于或在饮用水标准范围内。此外，还证明生物砂滤是消除臭氧氧化过程中形成的可生物降解化合物（如 NDMA）的有效附加屏障。附加的后臭氧氧化步骤的能量需求约为 0.035 kWh m(-3)，这相当于典型中型营养去除厂（5 g DOC m(-3)）的 12%。
