Optimization Of Butanol Fermentation And Kiketic Analysis By Clostridium Beijerinckii F-6

Under the double pressure of fossil fuel depletion and environmental pollution,it is thus extremely urgent to develop renewable and green energy to substitute fossil fuels.Butanol as one of the important emerging biofuels has got more and more attention with its excellent chemical properties such as higher energy content,volatility,hydroscopicity,and miscible with gasoline in any proportion.However,there are many critical technological problems to solve for achieving the large-scale industrial production of biobutanol.Reducing cost and enhancing butanol capacity is the basic problem to biobutanol technology for realizing industrialization.According to the key factors effect on butanol synthesis,in this study,the kinetic butanol synthesis parameters under different conditions were investigated by using kinetic models,and the key factors for butanol fermentation were optimized.Based on the above analysis,the pH-control coupled with butyrate regulation strategy affecting butanol fermentation were investigated,the results obtained are as follows:(1)The strain of Clostridium beijerinckii F-6 used in this study was screened by our laboratory.Various factors affecting on butanol fermentation such as temperature,initial pH,inoculum size and organic acid were firstly investigated by Gompertz model and scattered node interpolation method.Based on the kinetic analysis,the significant factors affecting the synthesis of butanol were screened,the central level of significant factors and the optimum conditions for butanol fermentation were determined.Results showed that initial pH,temperature,and exogenous butyrate were significant factors to affect butanol synthesis.The butanol yield reached maximum at the optimum fermentation conditions of initial pH7.0,temperature 37.16 ?,and butyrate addition 1.23g/L.The result was further verified by repeated experiments under optimal conditions.The predicted value was consistent to the measured values.Under the optimum conditions,the butanol yield and butanol productivity reached the maximum of 7.88g/L and 0.244g/L-1h-1 respectively,which were 77.08% and 76.81% higher than the control without optimization.(2)In order to elucidate the constant pH effect on butanol fermentation,the kinetics of bacteria growth,substrate consumption and butanol synthesis under various constant pH conditions were investigated.Results showed that the biomass reached the maximum at pH 6.5 while at pH 5.0 both glucose consumption and butanol yield reached the maximum.Based on kinetic analysis,pH 5.0 is the optimum level for butanol synthesis.(3)Based on the optimum pH level for butanol synthesis,pH-control coupled with butyrate addition was applied to further regulate butanol fermentation.Results showed that the pH-control with butyrate regulation strategy enhanced the dry weight cell,glucose consumption and butanol yield by 4.8%,21.3% and 210.3% respectively.This study provides an important basic theory and experimental method to enhance butanol production.It also provides corresponding kinetic theory and experimental basis for biobutanol industrialization.