Analysis of Microbial Community Succession during Methane Production from Baiyinhua Lignite

Biogas production from coal via anaerobic fermentation has received much attention in recent years. In the present work, the methane generation with Baiyinhua lignite by mixed flora derived from the coal bed water and anaerobic tank were investigated. The microbial community succession and the coal characteristics before and after methane production were analyzed, combing with high-throughput sequencing, proximate analysis, elemental analysis, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results showed that the bacteria community diversity was abundant, and the dominant phyla of bacteria were Firmicutes, Proteobacteria, Bacteroidetes, Thermotogae, Deferribacteres, Synergistete, and Spirochaetae. In contrast, the archaea community had low diversity, of which the main phylum was Euryarchaeota. Generally, both the bacterial and archaea biodiversities presented an initially increasing and then decreasing trend (0–40 days); however, the archaea diversity increased after 40 days of culture. In the gas production process, three groups of bacteria, including iron-reducing bacteria and sulfate-reducing bacteria assigned to Geovibrio, Macellibacteroides, and Desulfovibrio, were the main components. The results of proximate and elemental analyses of coal showed that moisture (+1.57%), volatile matter (Vdₐf, +1.64%), H (+0.1%), O (+1.35%), N (+0.28%), and S (+1.29%) increased and ash (−1.67%) and C (−3.02%) decreased. XRD showed that the anaerobic digestion of microorganisms mainly uses the organic carbon source in lignite. The FTIR results showed a significant increase in the hydroxyl group, ether oxygen bond and carboxyl and carbonyl groups decreasing, the aromatics basically invariant, and aliphatic functional groups dominated by saturated CH₂ decreasing significantly.