Research On Microorganism Liquefaction Process Of Weathered Coal

Coal is the main energy source of China,the reserves of low-rank coal resources are particularly abundant,how to make full and efficient use of this resource is a subject worthy of further research.The microbial liquefaction of coal refers to the use of microorganisms such as bacteria,fungi and actinomycetes to effect the dissolution,degradation,and liquefaction of coal,and to obtain products for the production of chemicals or fuels.It has the advantages of low energy consumption,mild reaction conditions,simple equipment,and high value-added products.Low-rank coal has the characteristics of low degree of metamorphism,high content of active functional groups,and high side chain and bridging,it is easily used by microorganisms to convert into water-soluble humic acids,thereby realizing utilization of low-rank coal resources.In this paper,we chose weathered coal and weathered coal pretreated by?NH₄?₂HPO₄ as materials.Phanerochaete chrysosporium,Coriolus versicolor,Aspergillus terreus,Penicillium oxalicum as experimental strains.The liquefaction methods using solid plates and the liquid shake culture were selected.The liquefaction of?NH₄?₂HPO₄ pretreated weathered coal and non-pretreated weathered coal by four experimental strains was studied.The main conclusions obtained were as follows:?1?After the four strains were activated and cultured,they were sprinkled with sterilized weathered coal samples.The results showed that the four strains could liquefy the?NH₄?₂HPO₄ pretreated weathered coal sample into bright black liquid beads.The liquefaction of the raw weathered coal is not significantly.The liquefied ability of four strains on the solid plate is:Penicillium oxalicum>Aspergillus terreus>Coriolus versicolor>Phanerochaete chrysosporium.?2?The liquid shake culture was selected to study the influence of the three factors of the culture time,the quantities of strains and the initial pH of the culture medium on the liquefaction of weathered coal,and it was showed that the liquefaction of the weathered coal were increased as the culture time increased.The liquefaction rate of the coal first increased and then became gentled.The changing process of the humic acid content of the product was also the same.With the increase of the quantities of strains,the liquefaction rate of weathered coal and the humic acid content in the liquefaction product increased first and then declined slightly,but the change was not significant.The higher the initial pH value of the culture medium,the higher the humic acid content of the product was.However,when the initial pH is alkaline,a part of the liquefaction rate may be the role of the added alkali.For the?NH₄?₂HPO₄ pretreated coal sample,when the temperature was 30°C,the rotation speed was 130 rpm,and the amount of bacteria was 3 holes,the initial pH was 9,the liquefaction rate could reach 50.52%by Coriolus versicolor.The content of total humic acid and water-soluble humic acid in the product was 46.92%and 36.20%.?3?We selected two methods of solid plate and liquid shake culture to study the liquefaction of mixed strains of?NH₄?₂HPO₄ pretreated weathered coal.The conclusion was:on the solid plate,the liquefaction effect of four mixed strains was the best.In the liquid culture,the mixed strains of Coriolus versicolors and Phanerochaete chrysosporium had the highest liquefaction rate at the temperature of30?,rotation speed of 130rpm,and the amount of bacteria inoculated with 5 holes for 12 days,which was 21.71%,and the content of total humic acid and water-soluble humic acid in the product was 37.85%and 31.24%.?4?The raw weathered coal,?NH₄?₂HPO₄ pretreated weathered coal and liquefaction product were tested by FTIR and XRD.The results showed that the aromatic hydrocarbon structure was reduced after pretreated by?NH₄?₂HPO₄.Microbial had degradation effect on macromolecular structure of weathered coal,and humic acid substances were formed in the liquefaction product.This paper selected weathered coal with less research at home and abroad as the material.In addition to the widely studied Phanerochaete chrysosporium and Coriolus versicolor in white rot fungi,the experimental strains also included the rarely studied Aspergillus terreus and Penicillium oxalicum.And the process of microbial liquefaction of weathered coal to obtain humic acid was studied.It will play a certain guiding role in the study of humic acid microbial fertilizer in the future.It also provides some practical references for the research of high efficiency strains in liquefied weathered coal and its matching of the coal.