Unravelling relationships between fluorescence spectra, molecular weight distribution and hydrophobicity fraction of dissolved organic matter in municipal wastewater. (December 2022)

• Record Type: Journal Article
• Authors: Ji, Wen-Xiang; Tian, Ye-Chao; Li, Ai-min; Gu, Xiao-Ming; Sun, Hong-Fang; Cai, Min-Hui; Shen, Shan-Qi; Zuo, Yan-Ting; Li, Wen-Tao
• Is Part Of: Chemosphere. Volume 308:Part 3(2022)
• Publication Date: 2022-12
• Subjects: Dissolved organic matter -- Size exclusion chromatography -- Molecular weight distribution -- Hydrophobic/hydrophilic fractionation -- Fluorescence property; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2022.136359
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: 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. Graphical abstract: Image 1 Highlights: SEC-DAD-FLD-OCD/OND was established to characterize DOM in municipal wastewater. MW distribution and hydrophobicity of DOM in wastewater were directly linked. EEM regions was used to predict the hydrophobicity and MW distribution of DOM.