| In order to determine the advantages of coproduction of hydrogen（H2）and methane（CH4）,and biological pretreatment with white rot fungi,and further strengthen the understanding of the generation characteristics of biogas production from coal,simulation experiments of biogas production（single process of CH4 production,cogeneration of H2 and CH4,and cogeneration of H2 and CH4 following pretreatment with white rot fungi）were conducted under suitable environmental conditions using long flame coal from China’s Yima coalfield.The characteristics of biogenic gas generation under different fermentation methods were analyzed.The chemical oxygen demand（COD）value and liquid products of fermentation were measured using the potassium dichromate method and gas chromatography-mass spectrometry,respectively,to reveal the degree of degradation of coal,and the metabolic rule of liquid products.The microbial adsorption characteristics and reaction heat were measured using high-throughput sequencing techniques and micro-calorimetry,respectively,to determine the adsorption and reaction heat characteristics of the coal-microorganisms.The results were as following: a.The formation of CH4 showed a certain lag phage during the cogeneration of H2 and CH4,and the hydrolysis stage（methanogenesis）and gas production cycle were significantly shortened.b.The COD value increased gradually during the single process of H2 production,and reached a maximum on day6（857.82 mg/L）.The COD value showed a variable trend during the process of CH4 production,and was generally low during the cogeneration of CH4 after pretreatment with white rot fungi,and the degree of coal degradation was the strongest.c.Volatile fatty acid,alkanes,alkenes,oxygen-bearing and nitrogenous organic compounds and heterocyclic compounds accumulated during the cogeneration period.Neonatal organic compounds,such as cycloalkane,nitrile,hydrazine,4-methyl-9H-fluorene and more alkanes,oxygen-bearing and nitrogenous organic compounds,were formed during the CH4 cogeneration phase.d.The typess and quantity of organic compounds during the CH4 cogeneration after pretreatment with white rot fungi were also greater than that during the single cogeneration process of H2 and CH4,and the single process of CH4 production.e.The generation of gas products differed markedly with adsorption capacity and reaction heat during the single process of CH4 production,and all phases resulted from an exothermic reaction.The maximum values of adsorption capacity and heat output were 1772.72 μg and 306.031 J/g,respectively.The cogeneration process of H2 and CH4 was an exothermic reaction,except the original untreated coal samples during the H2 production phase.The total heat output during the single cogeneration process of H2 and CH4 was less than that during the CH4 cogeneration after pretreatment with white rot fungi.f.A negative correlation between the contents of organic compounds and heat output and adsorption capacity was observed during the H2 production phase.The process of CH4 production showed the opposite trend.g.Methanthrix and Mobilitalea were the dominant genera in the peak for thermogenesis during single CH4 production.Pseudomonas was the dominant genus during the H2 production phase and hydrolysis phase of methanogenesis.Methanobacterium was the dominant genus at the end of CH4 production.This research not only provide data sources and support for the utilization of chemical products of high additional value,but also demonstrates the advantages of fermentation cogeneration and biological pretreatment,which may improve overall energy utilization and optimize the gas generation process.At the same time,the experimental results also enriches the biogas production mechanism of coal. |
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