The succession of microorganisms and organics in the process of methane generation by co‐degradation of anthracite and rice straw

Abstract

Summary Compared with the biodegradation of coal, the co‐degradation of coal and straw can significantly improve methane production, which is potential to increase biogenic coalbed methane (CBM) production. In the laboratory tests, the succession of microbial communities and organic compounds in the process of methane generation from among degradations of coal (C), rice straw (RS), and coal‐rice straw (CRS) were investigated by using with MiSeq and GC‐MS analytical instruments. The experimental results indicated that methane production in the cultivation CRS was about 12 times higher than that of C. A shift of dominant methanogen in inoculum was observed in the process of co‐degradation from acetoclastic Methanosaeta to methylotrophic Methanomethylovorans on the seventh day, finally to hydrogenotrophic Methanobacterium. The structures of bacteria and fungi also changed significantly in the process of co‐degradation which mainly enriched macromolecules degrading and volatile fatty acids (VFAs) metabolizing microbes to facilitate methane generation. Moreover, the value of pH decreased with enrichment of VFAs, especially butanoic acid, because VFAs were dominant in the intermediates of co‐degradation. The contents of VFAs were negatively corelated with methane production during cultivation suggesting they would contribute to methane production. The component of intermediates in co‐degradation was distinct from those in cultivations of C and RS especially after 7 days as revealed by principal component analysis and heatmap analysis. These results revealed that adding rice straw into coal biodegradation changed the metabolic pathway and methanogenesis in co‐degradation.