| Currently, using lignocellulose to produce ethanol is a hot spot in developmentof new energy. As the rapid consumption of non-renewable energy sources in the earth,it is of great significance to Chinese economic and social sustainable development touse abundant and cheap lignocellulose to produce ethanol instead of food.In this dissertation, the fermentation conditions for production cellulose forstrain Penicillium FZU-401screened from soil is optimized. As well as, the basicenzymatic properties were studied. Afterwards, the influences of many parameters onthe hydrolysis of cellulose were investigated. Finally, a newly establishedlignocellulose-ethanol fermentation process, membrane-coupled circulatinghydrolysis and fermentation (MCCHF) bioreactor, was firstly conducted to producefuel ethanol using filter paper as substrate.The main conclusions of this paper were:1．The best carbon source for cellulase production by Penicillium FZU-401is5%straw, and the best nitrogen source is0.8%mixture of ammonium chloride andurea at a proportion of3:4. Moreover, the other optimal conditions were: pH5.4,inoculum size2%, inoculum age50-60h. Under the most suitable conditions, the peakof cellulose production appeared after4-6days by adding0.2%of PEG-20000. As aresult, the enzymatic activity of cellulose in the optimized medium is5-fold of theoriginal one.2． It is found that when the dosage of enzyme is40FPU/g filter paper, theconcentration of reducing sugar23.94g/L would be achieved in32h at a content offilter paper of7.5%and at pH5.0. The addition of non-ionic surfactants, especiallythe addition of PEG20000, can markedly improve the efficiency of enzymatichydrolysis.3. The membrane-coupled circulating hydrolysis and fermentation (MCCHF)bioreactor was constructed, in which the enzymatic hydrolysis and ethanolfermentation were able to be conducted in their each optimal temperature. Theprimary experiments showed that the concentration of ethanol and the conversion of cellulose would be4.04g/L and0.135g ethanol/g filter paper, respectively, after thefermentation of48h, under a cellulose concentration3%, inoculum size5%, cellulosedosage40FPU/g filter paper, and membrane flux25mL/min, etc. The resultsindicated that the MCCHF process provides the potential for fuel ethanol productionwith lignocellulose, by comparison the efficiency of substrate, cellulase and cell of theMCCHF process, SHF (separate hydrolysis and fermentation) process and SSF(simultaneous saccharification and fermentation) process. |
