Molecular characterization of the composition and transformation of dissolved organic matter during the semi-permeable membrane covered hyperthermophilic composting

• Published in: Journal of hazardous materials 2022-03, Vol.425, p.127496-127496, Article 127496
• Main Authors: Sun, Bo, Li, Yongshuang, Song, Manjiao, Li, Rui, Li, Zaixing, Zhuang, Guoqiang, Bai, Zhihui, Zhuang, Xuliang
• Format: Article
• Language: English
• Subjects: Composting; Dissolved Organic Matter; Fourier transform ion cyclotron resonance mass spectrometry; Hyperthermophilic composting; Mass Spectrometry; Organic Chemicals; Semi-permeable membrane; Soil; Spectra
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.127496

Current knowledge of dissolved organic matter (DOM) in semi-permeable membrane-covered thermophilic compost (smHTC) is limited. Therefore, this study provided a comprehensive characterization of composition and transformation of DOM in smHTC using multiple spectroscopic methods and ultrahigh resolution mass spectrometry. The results showed that the values of SUVA280, SUVA254, A240‐400 (0.042, 0.048, 34.193) in smHTC were higher than those of conventional thermophilic composting (cTC) (0.030, 0.037, 18.348), and the increment of PV,n in smHTC were 2.4 times higher than that of cTC. These results suggested that smHTC accelerated the humification process by promoting the degradation of labile DOM and the production of humus-like substances. Mass spectrometry further confirmed that the DOM of smHTC possessed higher degree of aromatization and humification, based on the lower H/C (1.14), higher aromaticity index (0.34) and double bond equivalence (10.36). Additionally, smHTC increased the proportion of carboxyl-rich, unsaturated and aromatic compounds, and simultaneously improved the degradation of aliphatic/proteins, lipids, carbohydrates, along with even some refractory substances such as CHO subcategory (24.1%), especially lignin-like structures (14.8%). This investigation provided molecular insights into the composition and transformations of DOM in smHTC, and extended the current molecular mechanisms of humification in composting. [Display omitted] •smHTC possessed higher degradation efficiency and broader degradation capability.•smHTC promoted the degradation of labile DOM and formation of humus-like substances•Aromatization and humification of smHTC mainly occurred in hyperthermophilic phase.•The DOM of smHTC had a higher aromaticity and maturity than cTC.