A Research On The Key Technologies In The Cleaner Production Of Ethanol And Methane Production From Corn Stover Pretreated By Subcritical Water

Biomass energy is a kind of renewable energy.The corn stover as agricultural waste is a great potential for development.Using corn stover to produce ethanol and methane,not only can relieve the burning straw atmospheric pollution problem,but the ability to produce biofuels.In this paper,the subcritical water was employed to pretreat corn stover.The water-soluble portion and insoluble portion of the corn stover were conducted by methane fermentation and ethanol fermentation,respectively.Then the supernatant was reused after distilling ethanol and methane fermentation in the subcritical water pretreatment process.At the same time using high-throughput sequencing technology to explore microbial flora in the anaerobic sludge.The main contents and results were as follows:1.With the method of subcritical water pretreatment,the pretreatment conditions was: 190?,0 min.Two experimental group respectively for twenty cycles,the residue of twenty cycles the results of SEM was analyzed.The residue yield of corn stover has been about 65% stably.The content of lignin and hemicellulose decreased.The relative conte nt of cellulose increased.2.In the same conditions of subcritical water pretreatment,put the liquid pretreated of twenty cycles and ethanol distilled residual liquid together.Then add the anaerobic sludge on methane fermentation.Through methane volume,liquid pH,and the amount of reducing sugar in the fermented liquid before and after fermentation to explore the laws of methane fermentation as follows: With the cycles carrying on,the volume of methane reduced,and finally stabilized,while the pH is increased.After the methane fermentation,the reducing sugar content in the liquid is reduced greatly.3.In the same conditions of subcritical water pretreatment,the residue was first sterilized followed by simultaneous saccharification and fermentation using cellulase for 24 h and yeast for 96 h,respectively.The concentration of ethanol is 0.5%(v/v)after fermentation,while the concentration of ethanol increased to 0.8%(v/v)up to 0.9%(v/v)after add 10 FPU/g cellulase 1.5L.The concentration of glucose is about 1.2%(v/v)in the enzymolysis of 24 h.At 24 h the yeast was inoculated into the fermentation broth.A small amount of glucose is not utilized after 96 h.The yeast colonies is stable in each cycles.In the first and second day the yeast growth is strong,while it is begin to decline on the third day.The reason is perhaps that the ethanol accumulation hindered the growth of yeast.4.Comparison of the middle cycles' sludge and the original sludge by 16 S V4 information collection and analysis.The results of microbial flora as follows: The predominant flora in the sludge are Bacteroidetes,Chloroflexi,Firmicutes and Proteobacteria.With the cycles carrying on,the species richness of Euryarchaeota is decreased,while the species richness of Actinomycetales is increased.It is consistent with methane gas production rules.Under the environment selection pressure,the species richness is falling while uniformity is improving.Microbial flora in fermented liquid sample is stable as a whole,in addition to the individuals.