Variation of microbial community before and after biogas production with Shengli lignite in Inner Mongolia

In order to study the role of microbial community in lignite biogas production process and the change of coal sample properties before and after gas production,the lignite obtained from Shengli in Inner Mongolia was used as the substrate for gas production,and the enriched anaerobic flora in Sihe mining area was used as the starting bacterial community. In the laboratory scale,the lignite biogas production was conducted. The microbial community changes be- fore and after gas production were analyzed by Illumina high-throughput sequencing platform. Gas chromatography, scanning electron microscopy,etc. were used to analyze the methane production of lignite and the physicochemical properties of coal samples before and after gas production and the morphology of the coal surface. The results showed that Inner Mongolia Shengli lignite could be utilized by the enriched flora and produce methane with a biogas produc- tion cycle of 49 days,and the cumulative methane production was 83. 1 mL. The net methane production rate was 7． 84 mL / g coal. The diversity of bacterial communities in the biomass biogenic samples of lignite was abundant. The main dominant bacteria at phylum level were Firmicutes,Proteobacteria,WWE1,Bacteroidetes,Synergistetes and Def- erribacteres. The initial microbial flora had high diversity,however,the microbial diversity decreased after the biogas generation with lignite and basic medium. The microbial structure changed obviously at genus level,and the dominant bacteria W22,Proteiniclasticum,VadinCA02,Tissierella soehngenia,Clostridium and Desulfovibrio played important roles in the biogas generation. Inner Mongolia Shengli lignite had higher volatile matter,rich in hydrogen and oxygen,and the surface structure of coal was loose,with obvious cracks,which was beneficial to microbial adhesion and degrada- tion,and was suitable for biogas production. After the biogas production,lignite’ s volatile content,water and ash,the proportion of S and O elements decreased,however the percentage of fixed carbon and the H / C increased. The SEM results showed that a large number of short rod-like and spherical microbes absorbed onto the surface of coal,and also had similar microorganism nanowire structure.