AUTHOR=Yang Xiuqing , Liang Qi , Chen Yanmei , Wang Baoyu 

TITLE=Alteration of Methanogenic Archaeon by Ethanol Contribute to the Enhancement of Biogenic Methane Production of Lignite

JOURNAL=Frontiers in Microbiology

VOLUME=Volume 10 - 2019

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.02323

DOI=10.3389/fmicb.2019.02323

ISSN=1664-302X

ABSTRACT=Bioconverting coal to methane is a green, environmentally friendly method to reuse waste coal. In this study, heterologous bacteria were used for the gas-producing fermentation of lignite under laboratory conditions. To investigate the effect of ethanol on gas production and microbial flora structure, we added different ethanol concentrations during gas production. Results show that when the ethanol concentration was 1%, the best methanogenesis was achieved at 44.86 mL/g, which is twice the gas production of 0% ethanol. Before and after gas fermentation, the composition and structure of the coal changed, the volatile matter and fixed carbon increased, and the ash decreased. The absorbance value at characteristic peaks of all functional groups decreased, new peaks were generated at 2,300/cm, and the peak value disappeared at 3,375/cm. Thus, microorganisms interacted with coal, consumed it, and produced some new materials. The microbial flora changes during gas production were tracked in real time. The ethanol concentrations of 0.5% and 1% did not obviously change the bacterial communities but strongly influenced the archaeon communities by changing the methane production pathway. Without ethanol, this pathway was the nutrient type of acetic acid. When ethanol was added, the pathway was mainly hydrotrophic type. In summary, adding ethanol can increase the coalbed methane production, change the structure and composition of coal, and facilitate the interaction of microbe with coal. Therefore, the methanogenic archaeon changes could help improve the methane-producing ability of lignite in the presence of ethanol.