机构地区:[1]太原科技大学安全与应急管理工程学院,山西太原030024 [2]煤与煤层气共采国家重点实验室,山西晋城048204 [3]中国矿业大学资源与地球科学学院,江苏徐州221116 [4]国家煤层气质检中心,山西晋城048026
出 处:《煤田地质与勘探》2024年第12期72-83,共12页Coal Geology & Exploration
基 金:国家自然科学基金项目(42102218);山西省基础研究计划项目(202103021223283,202203021221143);2022年晋城市重点研发计划(高新领域)项目(20220118)。
摘 要:【目的和方法】为探索低压环境下CO_(2)生物甲烷化和煤炭微生物降解气化特征,选取低阶烟煤(Rmax=0.67%)作为发酵底物,利用CO_(2)和H_(2)营造低压氛围,开展为期96 d的微生物发酵产气实验。借助气相色谱、16S rRNA基因测序和低温液氮吸附测试分析生物气产出-微生物群落-煤结构内在变化规律。【结果和结论】结果表明:(1)相比于常规发酵,注入低压CO_(2)对CH_(4)的产出有抑制作用,CH_(4)产出效率呈现降低现象,H_(2)注入后很快被转化利用,H_(2)体积分数快速降低,促进了CH_(4)的产出,同时也改变了生物气产出方式,对发酵液中微生物群落结构也产生了深刻影响,表现为细菌中厚壁菌门(Firmicutes)相对丰度的降低和拟杆菌门(Bacteroidota)相对丰度的升高,尤其是拟杆菌门中S50_wastewater_sludge_group菌属始终为优势菌属,它与unclassified_W27菌属均呈现上升趋势,分析原因为后期H_(2)的注入,促进了它们的生长代谢。(2)古菌在属水平分布中,甲烷杆菌属(Methanobacterium)所占比例最大(47.66%~83.05%),其次是甲烷八叠球菌属(Methanosarcina)、甲烷囊菌属(Methanoculleus);得益于可以同时利用H_(2)+CO_(2)和乙酸等底物,Methanosarcina相对丰度增大趋势显著;而Methanoculleus是通过氢营养途径进行甲烷的合成,后期缺乏H_(2),其丰度也快速减小。(3)相比于原煤,低压CO_(2)的注入导致煤吸附能力的减弱,总孔容和比表面积的减小;随着低压CO_(2)注入越多,分形维数D_(1)和D_(2)分别出现了增大和减小趋势,煤中孔隙表面粗糙程度增加,孔隙结构复杂程度或均质化程度减小,考虑与微生物降解和碳酸盐沉淀形成的双重作用有关。研究结果丰富了煤炭生物降解与CO_(2)生物转化利用基础理论,尤其为煤层中CO_(2)生物转化埋存技术贡献一定的理论依据。[Objective and Methods]This study aims to investigate the characteristics of CO_(2) biomethanation and coal gasification through microbial degradation in a low-pressure environment.With low-rank bituminous coals(Rmax=0.67%)as fermentable substrates,this study conducted a 96-day gas production experiment through microbial fermenta-tion in a low-pressure CO_(2) and H_(2) environment.Using techniques including gas chromatography,16S rRNA gene se-quencing,and low-temperature liquid nitrogen adsorption,this study delved into the intrinsic variation patterns of bio-genic gas production,microbial communities,and coal structures.[Results and Conclusions]The results indicate that compared to conventional fermentation,the injection of low-pressure CO_(2) inhibited CH_(4) production,leading to a re-duced CH_(4) production efficiency.After the H_(2) injection,the injected H_(2) was consumed quickly,resulting in a rapid de-crease in the H_(2) concentration and contributing to CH_(4) production.Meanwhile,the H_(2) injection changed the production mode of biogenic gas,exerting a profound influence on the structure of microbial communities in fermentable liquids.Specifically,the relative abundance of Firmicutes and Bacteroidota increased.Notably,the S50_wastewater_sludge_group in Bacteroidota always predominated,trending upward together with the unclassified_W27 genus.This occurred due to the late-stage H_(2) injection,which accelerated the growth and metabolism of both bacterial genera.Regarding the distribution of archaea at the genus level,Methanobacterium represented the highest proportion(47.66%‒83.05%),fol-lowed by Methanosarcina and Methanoculleus sequentially.Benefiting from the simultaneous consumption of H_(2),CO_(2),and substrates such as acetic acid,the relative abundance of Methanosarcina exhibited a significant upward trend.In contrast,Methanoculleus,which synthesizes methane via the hydrogenotrophic pathway,displayed a rapidly decreasing relative abundance due to a shortage of H_(2) in the later stage.Compared t
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