Research On The Combination Of Supercritical/Subcritical Hydrolysis Of Cellulose Technology And Simultaneous Hydrogen And Ethanol Production By Extreme Thermophiles

Straw is composed of cellulose, hemi-cellulose and lignin, which is apromising energy source in the future. Supercritical/subcritical water treatmenttechnology can decompose cellulose/straw into monosaccharide andoligosaccharide efficiently, because of the strong solubility and high ionizabilityof supercritical water. Supercritical/subcritical water treatment can be regardedas an upstream process of straw using. High-temperature fermentation processcan produces hydrogen and ethanol from pentose, hexose and oligosaccharideefficiently, by using extream-themophiles at a temperature of70Centigrade.High-temperature fermentation process can be regarded as a downstream processof straw using. In this study, we aim at how to detoxification the hydrolysate andenhance the strain to combine the supercritical/subcritical water treatmenttechnology and High-temperature fermentation process.First, we analysed the constituent of the hydrolysate by using HPLC andGCMS. We found that the potential inhibitor in the hydrolysate were compoundswhich contain2⁴carbons, and they could be divided into four classes, furan,ketones, acids and derivatives of ketone and acid.Meanwhile, we enhanced the tolerance to toxic substances of the originalstrain by repeatedly batch culture for3months, and gained a new train E, whichhad a better energy recovery for detoxified hydrolysate fermentation. The strainE can use glucose, xylose and isomaltooligosacharide as carbon source but fiberoligosaccharides. Under the best detoxification method, the energy recovery rateof cellulose hydrolysate fermentation was7.30kJ/g sugar, and it was higher thanthe one of isomaltooligosacharide fermentation2.31kJ/g sugar.Then, we choose furfural, butanone and butanoic acid as the representativesof the inhibitors and found that if the anyone of the four kinds of inhibitors’concentration reached0.125g/L, the fermentation will be inhibited. If anyone ofthe four kinds of inhibitors’ concentration reached0.5g/L, the fermentation willstop.We used four methods to detoxify the hydrolysate. The result showed that the hydrothermal oxidation-activated carbon method is the most effective. Thedetection of HPLC and GCMS showed that after using hydrothermaloxidation-activated carbon detoxification, the furan was removed, and the ketoneturned to small acid and ether. The hydrogen and ethanol yield reached258.25mlhydrogen/g glucose and0.074mol ethanol/mol glucose. The energy yield reached960.22kJ/mol glucose.The highest hydrogen and ethanol yield reached221.42ml hydrogen/g cornstraw and0.662*10^-2g ethanol/g corn straw in the fermentation of detoxifiedcorn straw hydrolysate by strain ThE. The energy yield reached2.40kJ/g cornstraw.