Unraveling the evolution of dissolved organic matter in full-scale A/A/O wastewater treatment process using size exclusion chromatography with PARAFAC and nonnegative matrix factorization analysis. (15th May 2023)

• Record Type: Journal Article
• Authors: Cai, Min-Hui; Tian, Ye-Chao; Li, Ai-Min; Li, Yan; Han, Yu-Ze; Ji, Wen-Xiang; Zhou, Qing; Li, Jun; Li, Wen-Tao
• Is Part Of: Water research. Volume 235(2023)
• Publication Date: 2023-05-15
• Subjects: Humic substances -- Effluent organic matter -- Soluble microbial product -- Excitation emission matrix -- Biotransformation; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2023.119879
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: DOM changes in full-scale WWTP A/A/O process was characterized by SEC-DAD-FLD-OCD. PARAFAC and NMF analyses were used to postprocess SEC-FLD and -OCD chromatograms. Variation of biopolymer and HA-like fractions mainly occurred in anaerobic process. Anaerobic humification process may be associated with carbohydrate metabolization. Abstract: Changes in spectral features and molecular weight (MW) of dissolved organic matter (DOM) along the A/A/O processes in eight full-scale wastewater treatment plants (WWTPs) were characterized using size exclusion chromatography with a diode array detector, a fluorescence detector and an organic carbon detector in tandem (SEC-DAD-FLD-OCD) as well as bulk water quality parameters. The parallel factor (PARAFAC) and the nonnegative matrix factorization (NMF) analyses have been effectively applied to the postprocessing of SEC-FLD fingerprints and SEC-OCD chromatograms, respectively. Individual SEC-FLD-PARAFAC or SEC-OCD-NMF components may span a broad range of MW, indicating that these SEC fractions within the same component were cognate and varied coherently across the dataset samples. The SEC-FLD-PARAFAC modeling and SEC-OCD-NMF analysis have clearly and concisely presented that the dramatic decreases of dissolved organic carbon, UV absorbance at 254 nm and protein-like fluorescence at Ex280/Em350 nm in the anaerobic process were primarily associated with the degradation of the large MW proteinaceous and polysaccharide-like biopolymers. It has also revealed that fluorescence of humic acid-like fractions increased significantly during the anaerobic process, but fluorescence of fulvic acid-like and humic substances' building blocks decreased slightly. Laboratory experiments further confirmed the presence of the humification process in anaerobic processes, and the formation of humic acid-like fluorophores may be associated with carbohydrate metabolism. The combination of SEC-FLD-PARAFAC and SEC-OCD-NMF helped to establish the links between changes in bulk water quality parameters and the evolution of SEC MW fractions, which provides a more in-depth insight into wastewater DOM treatability and enables the optimization of wastewater treatment processes. Graphical abstract: Image, graphical abstract