Study On Fermentation Of Fuel Ethanol From Cornstalk

With the increasing depletion of oil resources, renewable clean energy has gained extensive concern and the fermentation of biomass to produce ethanol has been a hot research field of renewable energy. Since China's unique situation requires that the "non-food" route should be taken,corn cultivated area in China now ranks second in the world, reaching more than 40,000 acres and producing several hundred million tons of corn stalk. However, only less than 10% of corm stalk has been better put into use. This not only causes serious waste of resources, but also results in environmental pollution. Therefore, the utilization of corn stalk as raw material to produce ethanol has a very broad application prospect.The aim of this work was to carry out the disposal and utilization of agricultural wastes in local places and establish primary technological process for producing fuel ethanol from corn stalk. The pretreatment of raw material was performed by the biological method with the combination of physical and chemical methods to break the crystal structures among lignin, hemicellulose and cellulose. In this way, the accessibility of acid and enzyme was significantly improved and the coarse fibre content was increased by 16.31% after the hydrolysis of hemicellulose and the removal of lignin. Glucose was obtained by the degradation of cellulose or diluted acid. One robust strain of yeast maintained in the laboratory, which has ability to ferment the glucose to produce ethanol, underwent mutagenesis such as thermal shock to produce new strains and then one strain named Yeast X was screened. The new strain has great tolerance of acetic acid, phenol and ethanol. Ortogonality measure (OM) and response surface method (RSM) were employed to optimize fermentation culture medium and conditions. The ethanol and the percent conversion of glucose after the optimization were improved by 15.44% and 11.30%, respectively. Also, one xylose fermentation strain H3, which has great activity was obtained through careful screening and its fermentation conditions was optimized with the implementation of RSM. Theoretically, the ethanol yield was 1.447g / L.