Ethanol Production From Jerusalem Artichoke Tubers And Stalks

With more and more serious energy crisis and environmental pollution, the fuel ethanol has become a globle hotspot. As a kind of non-food crop Jerusalem artichoke, tuber and straw can be used to produce ethanol by microorganism, so Jerusalem artichoke is a good raw material for bioethanol fermentation.Firstly, in order to improve the economy of ethanol production from Jerusalem artichoke tubers, Jerusalem artichoke tubers were hydrolysised into reducing sugar with acid solution and used by Saccharomyces cerevisiae6525to produce ethanol. The effect of ratio of solid to liquid (w/w), concentration of acid, reaction temperature and reaction time on conversion rate of reducing sugar was studied. The nutrient type and concentration were optimized by response surface method. The optimum condition for Jerusalem artichoke hydrolysis was achieved with ratio of solid to liquid1/3, concentration of sulphuric acid1.5%, reaction temperature80℃, reaction time90min. Under the optimum condition, conversion rate of reducing sugar in the hydrolysate could achieve94.83%of the theoretical value. After neutralized with NaOH, MgSO43g/L, K2HPO41.5g/L and NH4HCO32.94g/L was added to the fermentation medium with response surface analysis, the concentration of ethanol was72g/L finally within36h, the productivity was2.0g/L/h, which has increased by9%comparing with the non-optimized result65.8g/L.Secondly, Jerusalem artichoke stalks were pretreated by dilute acid, the effect of ratio of solid to liquid (w/w), concentration of acid, pretratment temperature and reaction time on conversion rate of reducing sugar was studied. The optimum condition of pretreatment was achieved with ratio of solid to liquid1/8, concentration of sulphuric acid1.5%, reaction temperature121℃, reaction time60min. Under the optimum condition, conversion rate of reducing sugar in the hydrolysate could achieve53.7%of the theoretical value. After neutralized with NaOH, the hydrolysis of Jerusalem artichoke stalks was optimally carried out by adding30U/g of cellulose and30U/g xylanase separately. Separate hydrolysis fermentation (SHF) and simultaneous saccharification and fermentation (SSF), were used for ethanol production with three different strains, Kluyveromyces marxianus1727, Pichia stipitis JCM10742, Pichia. stipitis CBS5733. The strain with best ability of producting ethanol is Kluyveromyces marxianus1727, the concentrations of ethanol were25.91g/L and25.63g/L separately with SSF and SHF.Finally, the economy analysis on the basis of technology parameters showed the investment recovery period would be about5.4years. As the high cost of raw material would be significantly blocking the commercial steps.