Analysis Of Methane Production And Microbial Diversity In Coal Geological Microorganism Promoted By Ethanol

Microbial stimulation of coalbed methane(CBM)is considered to be a promising CBM regeneration method that can effectively alleviate energy shortages.Researchers at home and abroad have increased the production of CBM by microbial stimulation,microbial enhancement,increased coal solubility and bioavailability,especially in the presence of nutrients to stimulate microbial resuscitation and growth.Coal geological microbes are in an inactive state in a harsh and nutrient-poor environment,and require some environmental stimulation to better carry out metabolic activities.As a green,environmentally friendly and inexpensive organic matter,ethanol is gradually being used in the research of microbial stimulation of CBM.Domestic and foreign scholars have stimulated microbial activity by adding ethanol,founding that methane production can be increased.However,in the process of gas production,the structure and diversity of coal-related microbial flora and their relationship with ethanol are still unknown.In this study,the lignite from Shenhua Shengli Coalfield in Xilinhot,Inner Mongolia was used as the research object.The enriched domesticated culture solution in the 121 CBM Well of Sihe Mining Area in Shanxi was used as the inoculation source for 90 d heterogeneous ectopic gas production experiment.In order to explore the effect of ethanol on gas production,different levels of ethanol(0.5%,1%,2%)were added to the anaerobic bottle.During the gas production process,the gas composition of the headspace gas in the anaerobic bottle was periodically measured,and the physical and chemical properties of the coal sample before and after the fermentation were analyzed,and molecular ecological methods such as high-throughput sequencing,PCR-DGGE,real-time quantitative PCR,etc.were also used to analyze changes in microbial flora during gas production.The gas production results showed that the best effect of adding 1% ethanol was 44.86 m L/g.The analysis of the physical and chemical properties of coal showed that compared with the original coal sample,the structure of coal had changed after gas fermentation,and there were many volatile groups,fixed carbon,etc.,and new groups were produced,indicating that anaerobic fermentation had an effect on coal structure,but there was little change in the structure of adding ethanol and not adding ethanol.The addition of ethanol mainly increased the bioavailability of coal.The microbial flora structure analysis showed that the main bacterial bacteria involved in the whole gas production process were Proteus,Desulfovibrio,Macellibacteroides,Clostridium,Paraclostridium,Citrobacter,and a small number of Enterococcus and Tyzzerella.The addition of ethanol had little effect on the bacterial flora,but the archaea was obviously affected by ethanol;the Methanosarcina was gradually increased with the prolongation of fermentation time when no ethanol was added;there was a significant increase in Methanobacterium in the group of adding ethanol;it could be seen that the addition of ethanol led to a change in the type of gas produced by methane in this experiment,which was changed from the gas type of mixed type and acetic acid type to the type of gas produced by hydrogen nutrition type.The number of microbial population analysis showed that there was no significant difference between the number of flora in bacteria and archaea during the short-term fermentation time(P>0.05);with the prolongation of fermentation time,there was a significant difference between the number of the experimental group added ethanol and the control group(P<0.05).In summary,this study clarified that ethanol could stimulate the production of CBM by stimulating microorganisms.The addition of it caused a change in the type of methane gas production,and led to a significant increase in the number of microbial flora at the same time,but its role was also affected by the fermentation time.Ethanol is cheap and non-toxic,and it can be used in large-scale production practice,using ethanol to increase production of CBM has certain feasibility and economic benefits.At the same time,it provides a preliminary basis for the mechanism of ethanol-stimulated microbial production of CBM.