State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, China.
State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, China.
Chemosphere. 2022 Dec;308(Pt 3):136359. doi: 10.1016/j.chemosphere.2022.136359. Epub 2022 Sep 10.
The characteristics of dissolved organic matter (DOM) in the influent and secondary effluent from 6 municipal wastewater treatment plants (WWTPs) were investigated with a size exclusion chromatogram (SEC) coupled with multiple detectors to simultaneously detect ultraviolet absorbance, fluorescence, dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) as a function of molecular weight (MW). The SEC chromatograms showed that biopolymers (>6 kDa) and humic substances (0.5-6 kDa) comprised the significant fraction in the influent, while humic substances became the abundant proportion in the secondary effluent. Direct linkages between MW distribution and hydrophobicity of DOM in the secondary effluent were further explored via SEC analysis of XAD resin fractions. DON and DOC with different hydrophobicity exhibited significantly distinct MW distribution, indicating that it was improper to consider DOC as a surrogate for DON. Different from DOC, the order of averaged MW in terms of DON was hydrophobic neutral ≈ transphilic neutral > hydrophobic acid > transphilic acid > hydrophilic fraction. Fluorescence spectral properties exhibited a significant semi-quantitative correlation with MW and hydrophobicity of DOC, with Pearson's coefficients of -0.834 and 0.754 (p < 0.01) for biopolymer and humic substances. Meanwhile, regional fluorescence proportion was demonstrated to indicate the MW and hydrophobicity properties of DON at the semi-quantitative level. The fluorescence excitation-emission matrix (EEM) could be explored to provide a rapid estimation of MW distribution and hydrophobic/hydrophilic proportion of DOC and DON in WWTPs.
采用尺寸排阻色谱（SEC）与多种检测器联用的方法，对 6 座城市污水处理厂（WWTP）进水中及二级出水中的溶解性有机物（DOM）特征进行了研究，以同时检测紫外吸光度、荧光、溶解有机碳（DOC）和溶解有机氮（DON）随分子量（MW）的变化。SEC 色谱图表明，生物聚合物（>6 kDa）和腐殖质（0.5-6 kDa）是进水DOM 的主要成分，而在二级出水中，腐殖质成为主要成分。通过 XAD 树脂级分的 SEC 分析进一步探讨了二级出水中 MW 分布与 DOM 疏水性之间的直接关系。不同疏水性的 DON 和 DOC 表现出明显不同的 MW 分布，这表明不能将 DOC 作为 DON 的替代物。与 DOC 不同，DON 的平均 MW 顺序为疏水性中性≈芳香性中性>疏水性酸>芳香性酸>亲水性部分。荧光光谱性质与 DOC 的 MW 和疏水性之间存在显著的半定量相关性，生物聚合物和腐殖质的 Pearson 系数分别为-0.834 和 0.754（p < 0.01）。同时，区域荧光比例在半定量水平上表明了 DON 的 MW 和疏水性特征。荧光激发-发射矩阵（EEM）可用于快速估计 WWTP 中 DOC 和 DON 的 MW 分布和疏水性/亲水性比例。
