Molecular Insights into the Transformation of Membrane-Concentrated Landfill Leachate during the Cu-Fenton Process
Chunying Teng, Bingliang Zhang, Zhi Ping Xu, Kanggen Zhou, Xuekai Zhang, Lijia Liao, Wei Chen
Abstract
Membrane-concentrated landfill leachate (MCLL) is a type of recalcitrant wastewater with extremely low biodegradability. Identification of the recalcitrant components and their degradation characteristics is crucial for developing effective treatment strategies. In this work, spectroscopic techniques were integrated with chemometrics and Fourier transform ion cyclotron resonance-mass spectrometry to track the compositional changes of dissolved organic matter (DOM) in MCLL during Cu-Fenton treatment. The degradation of both fluorescent and chromophore components followed pseudo-first-order kinetics during the Cu-Fenton process, with the sequential order of fluorescent DOM (terrestrial humic-like > microbial humic-like) > chromophore DOM (aromatic structure > conjugated unsaturated structure). The degradation characteristics of DOM in MCLL exhibited variations in response to elemental compositions and molecular structure. Nitrogen-containing compounds showed an increase in relative abundance, while sulfur-containing compounds progressively decreased. Lipids, aliphatic/proteins, aromatics, and lignin/carboxylic-rich alicyclic molecule-like structure with a low O/C ratio were effectively removed, resulting in the transformation of DOM from an unsaturated redox state to a saturated oxidation state. This study provides a comprehensive insight into the transformation of DOM in MCLL during the Cu-Fenton process, which demonstrates its potential as a promising technology for refractory wastewater treatment.