@article{Guo2026, 
author = {Kai Guo and Yizong Huang and Jinhe Jiang and Kai Wu and Wudi Zhang and Fang Yin},
title = {Effects of 8-hydroxyquinoline on the anaerobic digestion performance and action mechanism of Chinese cabbage waste},
year = {2026},
journal = {Transactions of the Chinese Society of Agricultural Engineering},
volume = {42},
number = {15},
pages = {53-62},
keywords = {vegetable waste, anaerobic digestion, methane, microbial community, 8-hydroxyquinoline, electrochemical response},
url = {https://www.sciopen.com/article/10.11975/j.issn.1002-6819.202604007},
doi = {10.11975/j.issn.1002-6819.202604007},
abstract = {Anaerobic digestion is one of the most important processes to realize the conversion of vegetable waste into carbon-based materials. This study aims to investigate the effects of 8-hydroxyquinoline on methane production, intermediate metabolite conversion, microbial community structure, and electrochemical properties during anaerobic digestion of Chinese cabbage wastes. The low and high concentrations of 8-hydroxyquinoline were also selected to clarify the microbial and electrochemical mechanisms during methane production. Batch anaerobic digestion experiments were conducted with three treatments: a control without 8-hydroxyquinoline, a low-dose treatment containing 50 mg/L 8-hydroxyquinoline, and a high-dose treatment containing 150 mg/L 8-hydroxyquinoline. Each treatment was performed in triplicate at 35 °C. Biogas production, methane production, volatile fatty acids, and methane-production kinetics were determined to verify the concentration regulation for risk assessment. Microbial community composition was characterized by high-throughput sequencing of the 16S ribosomal RNA gene. Co-occurrence network analysis was used to evaluate potential correlations among bacterial and archaeal taxa. Cyclic voltammetry and electrochemical impedance spectroscopy were applied at the initial, acidification, and peak methane-production stages to assess redox activity and interfacial electron-transfer characteristics. The results show that there was a strong effect of 8-hydroxyquinoline concentration. Compared with the control, the 50 mg/L treatment increased cumulative biogas production from 1 935.00 mL to 2 134.00 mL, and cumulative methane production from 568.80 mL to 693.09 mL, with increases of 10.28% and 21.85%, respectively. In contrast, the 150 mg/L treatment reduced cumulative biogas and methane production to 1 162.00 mL and 211.32 mL, indicating decreases of 39.95% and 62.85%, respectively. Modified Gompertz fitting showed that the predicted methane-production potential increased from 552.03 mL in the control to 673.03 mL in the 50 mg/L treatment, whereas there was a decrease of 198.54 mL in the 150 mg/L treatment. The maximum methane-production rate decreased by 84.41% in the high-dose treatment, compared with the control. The peak of total volatile fatty acids shifted from day 25 in the control to day 28 in both high and low 8-hydroxyquinoline treatments. The proportion reached 30.12% in the 150 mg/L treatment on day 5, while acetate accumulated during the later digestion stage. The high-dose exposure impaired the conversion of acidification products into methane. Microbial analysis showed that the relative abundance of Chloroflexota decreased from 57.16% in the control to 44.13% in the 150 mg/L treatment, while unidentified Anaerolineaceae decreased from 56.65% to 43.47%. These taxa were associated with primary fermentation and degradation of complex organic matter. Although Methanocorpusculum increased from 76% in the control to 83% in the high-dose treatment, the methane yield remained markedly lower, indicating that methanogen abundance failed to directly represent methanogenic activity. Co-occurrence networks showed that there were more nodes and edges in the bacterial network than in the archaeal network. Positive correlations predominated, indicating that substrate hydrolysis, acidification, and syntrophic fatty-acid conversion depended on coordinated interactions among multiple bacterial groups. Electrochemical responses varied among digestion stages. During the initial stage, the charge-transfer resistance values of the control, 50 mg/L, and 150 mg/L treatments were 311.9, 307.9, and 367.8 Ω, respectively. The high-dose treatment therefore increased the initial charge-transfer resistance by 17.9%, compared with the control. During the acidification stage, the differences among treatments were below 1.9%. At the peak methane-production stage, low charge-transfer resistance in the 150 mg/L treatment failed to obtain high methane production, indicating that electrochemical resistance itself does not represent the overall methanogenic performance. Low-dose 8-hydroxyquinoline promoted methane recovery to maintain the coordinated relationship among substrate degradation, volatile fatty acid conversion, and methane generation. High-dose 8-hydroxyquinoline inhibited methane production to increase the initial electron-transfer resistance. Acidification products were accumulated to reduce key fermentative taxa, and then disrupt metabolic cooperation between fermentative bacteria, syntrophic microorganisms, and methanogenic archaea. These findings can provide a mechanistic basis for risk assessment and regulation in the anaerobic treatment of vegetable wastes with 8-hydroxyquinoline residues.}
}