| Fluidized mining technology provides a new idea for the mining of deep coal resources,difficult to mine coal seams or legacy coal resources in China,among which coal microbial gasification is an important part of fluidized mining technology,but there are also problems such as low gasification efficiency,so it is of great scientific and engineering significance to carry out research on the mechanism and technology of enhanced coal microbial gasification.In this thesis,methane production by microbial anaerobic fermentation under the condition of applied electric field was investigated,and the mechanism of microbial degradation of coal under the condition of applied electric field,the gas production pattern under different voltage and different coal grades were studied by combining solid phase Raman spectroscopy,electron microscopy,liquid phase GC/MS organic matter and microbial community analysis.Firstly,the effect of different voltage values on methane production under the applied electric field was investigated,and it was shown that the highest total methane production was achieved at 1.5 V with 7.91 ml/g coal methane gas,and the methane production was not satisfactory at either too high or too low voltage conditions.The abundance of Clostridium＿sensu＿stricto increased under the condition of applied electric field,which decomposed more coal macromolecule aromatic compounds and promoted the process of coal hydrolysis,resulting in the increase of o-xylene and1,3-dimethylbenzene in solution,and the abundance of Proteiniborus The abundance of Proteiniborus was reduced,which reduced the toxic substances such as erucic acid amide produced by protein hydrolysis,and the applied electric field also promoted Methanosarcina,which finally facilitated the methane production from coal decomposition under the action of various methanogenic Archaea spp.At the same time,the microbial degradation of coal under different coal rank conditions with applied electric field was mastered.The study showed that more methane gas was produced under the condition of low rank coal as substrate,and the amount of methane gas production was negatively correlated with coal rank;as low rank coal contained more cellulose,lignin,hemicellulose and humus,it was more easily biodegraded.In contrast,middle-rank and high-rank coals are more solid compared with low-rank coals because most of the carbon elements exist in the form of stable carbon after the coalification process at higher temperatures,and contain less organic substances that are easily degraded by microorganisms;and more substances with toxic effects on microorganisms are found in the residual liquid of high-rank coals,which affects the gas production under high-rank coal conditions;low-rank coals have the most species of bacteria among them,with more abundant The lower-rank coals have the most abundant microorganisms,which facilitate the degradation of more organic matter and thus promote the production of substrates required for methane production,thus increasing the production of methane gas.The experimental results demonstrate that the applied electric field conditions can enhance the microbial gasification of coal and further enrich the in situ microbial gasification technology of coal.This thesis contains 36 figures,22 tables,and 108 references. |
