State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, China.
State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, China; Research Center for Environmental Nanotechnology (ReCENT), Nanjing University, Nanjing 210023, China.
Water Res. 2021 Jul 1;199:117158. doi: 10.1016/j.watres.2021.117158. Epub 2021 Apr 18.
Ultraviolet-based advanced oxidation processes (UV-AOPs) are very promising in advanced treatment of municipal secondary effluents. However, the transformation of dissolved effluent organic matter (dEfOM) in advanced treatment of real wastewater, particularly at molecular level, remains unclear. In this study, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) coupled with multiple statistical analysis were performed to better understand the transformation of dEfOM in UV/HO, UV/persulfate (UV/PS), and UV/chlorine treatments. An obvious increase in oxygen content of dEfOM was observed after every UV-AOPs treatment, and the detailed oxygenation processes were further uncovered by mass difference analysis based on 24 types of typical reactions. Generally, UV/HO process was subjected to the most oxygenation reactions with the typical tri-hydroxylation one (+3O), whereas di-hydroxylation reaction (+HO) was dominant in UV/PS and UV/chlorine processes. Additionally, the three UV-AOPs shared the majority of precursors, and more proportions of unique products were identified for each process. The precursors with lower H/C and higher aromaticity were readily degraded by UV/chlorine over UV/HO and UV/PS, with the products featuring lower molecular weight. Moreover, dEfOM of high aromaticity tended to produce chlorinated byproducts through addition reactions in chlorination and UV/chlorine processes. Among these UV-AOPs, the highest reduction of both acute toxicity and specific UV absorbance at 254 nm (SUVA) was observed for UV/chlorine, implying the potential for UV/chlorine process in advanced treatment of wastewater. In addition, acute toxicity was highly correlated with SUVA and CHOS compounds. This study is believed to help better understand the different fates of dEfOM in real wastewater during UV-AOPs treatment.
基于紫外线的高级氧化工艺（UV-AOPs）在市政二级出水的深度处理中具有广阔的应用前景。然而，实际废水深度处理中溶解性有机物（dEfOM）的转化，尤其是在分子水平上的转化，仍不清楚。在本研究中，采用傅里叶变换离子回旋共振质谱（FT-ICR-MS）结合多种统计分析方法，以更好地了解 UV/HO、UV/过硫酸盐（UV/PS）和 UV/氯处理中 dEfOM 的转化。在每一种 UV-AOPs 处理后，dEfOM 的含氧量明显增加，通过基于 24 种典型反应的质量差分析进一步揭示了详细的氧化过程。一般来说，UV/HO 过程经历了最多的氧化反应，其中典型的三羟基化反应（+3O）占主导地位，而二羟基化反应（+HO）在 UV/PS 和 UV/氯过程中占主导地位。此外，这三种 UV-AOPs 有很大一部分共同的前体，并且每个过程都鉴定出更多比例的独特产物。在 UV/氯和 UV/PS 中，H/C 比低和芳香度高的前体容易被降解，产物的分子量也较低。此外，高芳香度的 dEfOM 倾向于通过氯化和 UV/氯过程中的加成反应生成氯化副产物。在这些 UV-AOPs 中，UV/氯的急性毒性和 254nm 处特定紫外吸光度（SUVA）的降低幅度最大，这表明 UV/氯工艺在废水深度处理中的应用潜力。此外，急性毒性与 SUVA 和 CHOS 化合物高度相关。本研究有助于更好地了解实际废水在 UV-AOPs 处理过程中 dEfOM 的不同命运。
