The analysis of liquid phase parameters in the production of methan e from fish meal combined with anaerobic digestion of coal

Abstract To enhance methane production from the anaerobic digestion of lignite coal, fishmeal was usedas an additive, and the influence mechanism on methane production was studied. Methane production experiments were conducted at 35°C using activated sludge as the bacterial inoculum, with varying proportions of coal and fishmeal. The differences in gas production were analyzed using liquid-phase test data such as gas fraction, chemical oxygen demand, and three-dimensional fluorescence spectroscopy and gas chromatography–mass spectrometry data. According to the results of the liquid-phase parameters, across all groups, fishmeal addition resulted in a more stable pH, lower ammonia nitrogen and volatile fatty acid concentrations, more adequate organicmatter decomposition, and efficiently utilized volatile fatty acids. As the fishmeal proportion increased, enzyme activity, the dissolved sugar content, the protein content, and the lipid content first increased and then decreased, and the group with a coal-to-fishmeal ratio of 2:1 exhibited the highest diversity of compounds, with 61 compounds. Moreover, the addition of an appropriate amount of fishmeal enhanced the reaction system, increased the gas and methane production, and shortened the reaction period. At a coal-to-fishmeal ratio of 2:1, the stagewise gas production and methane production was the highest: 480 mL/d and 353.42 mL/d, respectively. Overall, the results of this study provide a novel method for improving methane production based on the anaerobic digestion of lignite coal.