The Research On Pretreatment Of Cluster Bamboo Fiber And Enzymatic Fermentation For Ethanol Production

Cellulosic biomass Enzymatic into ethanol, without pretreatment the enzymatic hydrolysis rate of the natural state bamboo cellulose biological resources is very low, so raw materials must be pretreated, In the useing process of bamboo to produce fuel ethanol,The pre-treatment is one of the most expensive, the most immature technical aspects.The main reason for the low ethanol production rate, for one thing is low enzymatic hydrolysis of lignocellulose, for another thing,is at the same time simple sugars of the enzymatic hydrolysis of cellulose and hemicellulose can not be actively used to fuel ethanol.Based on the purpose of exploring the best pretreatment parameters of bamboo steam blasting and improving fermentation ethanol production,Study Steam explosion pretreatment of bamboo fiber, study conditions of the mixed cellulose enzymatic hydrolysis bamboo blasting slag, study the process of mixed bacteria fermentation use steam blasting bamboo to produce ethanol,reached the following conclusions:(1) In Steam explosion pretreatment, after the raw materials were ground to0.5-1.0cm, the explosion reduced sugar yield was6.85%. The moisture content of10%was favorable for the degradation of hemicellulose and partial removal of lignin in the process of steam explosion, thus producing the highest reduced sugar yield of7.95%. Along with the increases in explosion pressure and duration, the reduced sugar yield substantially and gradually increased, but under severe explosion conditions (pressure>3.5MPa, time>240s), the reduced sugar yield declined, with corresponding degradation of hemicellulose, cellulose, and lignin. and also produce toxic substances that inhibit subsequent enzymatic hydrolysis. The steam explosion pressure was shown to be more significant than duration on explosion effect, therefore perature3.0Mpa and time240s are preferred for good treatment effect.(2) Utilize Steam explosion pretreatment bamboo as raw material for Enzymatic, conducte a comprehensive investigation mainly from the seven factors that affect the enzymatic hydrolysis of cellulose, and do orthogonal optimization with the the four-factor,reaction temperature, pH, the amount of enzyme, beta-glucosidase/filter paper,Optimize and obtaine the optimum conditions for enzymatic hydrolysis of bamboo,as follows:reaction temperature50℃, initial pH5.2, substrate concentration of10%,0.3%Tween-20, the amount of enzyme35IU/g,beta-glucosidase enzyme activity/filter paper is1.0, hydrolysis48h. Do Fermenter validate larger experiment,30.37g/L of reducing sugars can be generated, the saccharification was57.49%.(3) Using mixed cellulose enzyme hydrolysis the bamboo steam explosion slag and mixed strains fermentation into ethanol, the fermentation strains KO11, Saccharomyces cerevisiae, KOll and Saccharomyces cerevisiae,10%of the substrate on SHF and fermentation for ethanol production of8.37g/L,13.08g/L,14.60g/L, ethanol yield were31.07%,48.55%,54.20%, and the mixed strains fermentation ethanol is best.10%of substrate concentration on SSCF with combination bacterias, can produce ethanol of16.81g/L, ethanol yield of63.39%, compared with SHF, SSCF ethanol yield increased16.96%;to a certain extent,jncreasing the substrate concentration will decreases enzymatic saccharification efficiency, but fed-batch can improve the utilization of the substrate; it is not obvious that change the temperature of the fermentation process for improving the fermentation effect. Selecting the fermentation speed of120r/minis is more appropriate. Doing Amplification experiments with fermentation tank,When fermented to96h,ethanol production of17.65g/L, ethanol yield of65.52%.(4) Doing SEM scanning electron microscope with blasting residue and fermentation residue, SEM observation show that the pressure increase and time exacerbated, to some extent,destroyed the structure of lignocellulose, isolated cellulose, increased roughness and the pore structure of cellulose, increase cellulase accessibility, after enzymatic hydrolysis, hemicellulose and cellulose debris degradated basicly, which contribute to the conversion of the fermentation with hemicellulose and cellulose of bamboo.