Study On Microorganism Liquefaction Of Low-rank Coal In Xinjiang

In this study, coal and coal water samples were collected from the different coalmines regions of Xinjiang. Our research foused on the isolation of microbes and thescreening of low-rank coal-degrading microbes from the coal and coal water samples,and the low-rank coal liquefaction by using microbial conversion technology was alsoproceeded.A total of1099microbes were obtained from coal samples by using CDA, NAand SDA medium cultivation, and they were preserved for establishing a microbiallibrary through methods of slope cryopreservation, semi-solid puncture andfreeze-drying, respectively. Hereinto, there were934strains of bacteria, accountingfor84.99%;129strains of fungi, accounting for11.74%;36strains of actinomycetes,accounting for3.27%.Degrading bacteria screening experiment was conducted under the solid medium,and6strains numbered1,4,8,98,123and201were screened, which could convertlignite particles into black droplets. Strains rescreening experiment was carried outunder liquid medium in the second round, and4strains numbered1,4,8, and201were proved with the good ability of degradating low-rank coal into liquefied product.The liquefied product was a kind of shiny black material, which can be dissolved inalkali, but not in ethanol. According to molecular biology identification, strain No.1was Davidiella sp.; strain No.4and strain No.8were Penicillium sp.; strain No.201was Streptomyces sp.. Different from other three strains, as far as we know, Davidiellasp. has never been reported in publications. It is the report of dissolving coal capacityof Davidiella sp. for the first time.The optimum technological conditions of strain No.1for liquefying low-rankcoal have been obtained through orthogonal test. The results showed that the optimalparameter combinations were coal particle size (100mesh), coal sampleconcentrations (2g/150ml), liquefaction time (28d), and liquefaction temperature (25 ℃). The effect of these factors on coal conversion rate was ranked as following:liquefaction time> liquefaction temperature> coal particle size> coal sampleconcentrations. After condition optimization, the highest liquefying conversion rate oflignite from Sha’er Lake reached56.69%through Davidiella sp.(strain No.1)treatment for28d.Four kinds of samples consisting of lignite, lignite processed with nitric,liquefaction cinder of lignite and liquefaction product of lignite were analyzed byelemental analysis and FTIR technique. The results showed that functional groups ofnaphthenic as well as aromatic benzene rings were degraded, which indirectly provedthe liquefying function of Davidiella sp. to Sha’er Lake lignite. By monitoring theoxidase and pH value during fermentation process，we observed that the liquefactionmechanism of strain No.1was combination of enzymatic-liquefying mechanism andalkali-liquefying mechanism. Strain No.1is a degrading strain of Xinjiang low rankcoal with potential for development.