State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, China; School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Water Res. 2017 Oct 1;122:246-257. doi: 10.1016/j.watres.2017.05.074. Epub 2017 Jun 1.
In this study, nitrate formation from ammonium and/or dissolved organic nitrogen (DON) was investigated as a novel surrogate parameter to evaluate the abatement of micropollutants during ozonation of synthetic waters containing natural organic matter (NOM) isolates, a natural water and secondary wastewater effluents. Nitrate formation during ozonation was compared to the changes in UV absorbance at 254 nm (UVA) including the effect of pH. For low specific ozone doses UVA was abated more efficiently than nitrate was formed. This is due to a relatively slow rate-limiting step for nitrate formation from the reaction between ozone and a proposed nitrogen-containing intermediate. This reaction cannot compete with the fast reactions between ozone and UV-absorbing moieties (e.g., activated aromatic compounds). To further test the kinetics of nitrate formation, two possible intermediates formed during ozonation of DON were tested. At pH 7, nitrate was formed during ozonation of acetone oxime and methyl nitroacetate with second-order rate constants of 256.7 ± 4.7 M s and 149.5 ± 5.8 M s, respectively. The abatement of the selected micropollutants (i.e., 17α-ethinylestradiol (EE2), carbamazepine (CBZ), bezafibrate (BZF), ibuprofen (IBU), and p-chlorobenzoic acid (pCBA)) was investigated for specific ozone doses ≤1.53 mgO/mgDOC and its efficiency depended strongly on the reactivity of the selected compounds with ozone. The relative abatement of micropollutants (i.e., EE2 and CBZ) with high ozone reactivity showed linear relationships with nitrate formation. The abatement of micropollutants with intermediate-low ozone reactivity (BZF, IBU, and pCBA) followed one- and two-phase behaviors relative to nitrate formation during ozonation of water samples containing high and low concentrations of nitrate-forming DON, respectively. During ozonation of a wastewater sample, the N-nitrosodimethylamine formation potential (NDMA-FP) during chloramination decreased with increasing specific ozone doses. A good correlation was obtained between NDMA-FP abatement and nitrate formation. Therefore, nitrate formation after pre-ozonation may be a useful parameter to estimate the reduction of the NDMA-FP during post-chloramination. Overall, the results of this study suggest that nitrate formation (possibly in combination with UVA abatement) during ozonation of DON-containing waters may be a good surrogate for assessing the abatement of micropollutants and the NDMA-FP.
在这项研究中，研究了从铵和/或溶解有机氮（DON）形成硝酸盐作为评估含天然有机物（NOM）分离物的合成水、天然水和二级废水的臭氧化过程中微污染物去除的替代参数。比较了臭氧化过程中硝酸盐的形成与 254nm 处紫外吸光度（UVA）的变化，包括 pH 的影响。对于低特定臭氧剂量，UVA 的去除效率高于硝酸盐的形成。这是由于臭氧与提出的含氮中间产物之间反应的相对限速步骤。该反应不能与臭氧与 UV 吸收部分（例如，活化芳香族化合物）之间的快速反应竞争。为了进一步测试硝酸盐形成的动力学，测试了 DON 臭氧化过程中形成的两种可能的中间体。在 pH 7 下，乙酮肟和甲基硝基乙酸在臭氧化过程中形成硝酸盐，其二级速率常数分别为 256.7±4.7M s 和 149.5±5.8M s。研究了特定臭氧剂量≤1.53mgO/mgDOC 时选定的微污染物（即 17α-乙炔基雌二醇（EE2）、卡马西平（CBZ）、贝扎贝特（BZF）、布洛芬（IBU）和对氯苯甲酸（pCBA））的去除效率，其去除效率强烈取决于所选化合物与臭氧的反应性。具有高臭氧反应性的微污染物（即 EE2 和 CBZ）的相对去除率与硝酸盐的形成呈线性关系。具有中低臭氧反应性的微污染物（BZF、IBU 和 pCBA）的去除率相对于高浓度和低浓度硝酸盐形成 DON 的水样臭氧化过程中的硝酸盐形成分别呈现单相和两相行为。在废水样品的臭氧化过程中，氯胺化过程中的 N-亚硝基二甲胺形成潜能（NDMA-FP）随着特定臭氧剂量的增加而降低。NDMA-FP 去除与硝酸盐形成之间存在良好的相关性。因此，预臭氧化后硝酸盐的形成可能是估计后氯胺化过程中 NDMA-FP 减少的有用参数。总的来说，这项研究的结果表明，含 DON 水的臭氧化过程中硝酸盐的形成（可能与 UVA 去除相结合）可能是评估微污染物和 NDMA-FP 去除的良好替代参数。
