Research On Ethanol Production From Sweet Sorghum Stalk In SSF And Using Of Fermentation Residue

Macroergic crop-sweet sorghum, whose stalks have plenty of sugar, which can be used for producing ethanol. Research on production of ethanol from sweet sorghum stalk in SSF was done in this experiment, and the fermentation conditions, styles and using of sweet sorghum residue were studied. The paper provided some proves for industrialized production of sweet sorghum stalk in SSF.Firstly, the optimal alcoholic fermentation conditions in SSF were studied. The results showed that with 0.50%yeast, fermentation for 24h, pH 5.0, 0.5% (NH₄)₂SO₄ and 0.5% CaCl₂ according to the amount of sweet sorghum, maximum ethanol was produced. In above fermentation conditions, sweet sorghum stalks which contain 13% total sugar and 80% water content, were wringed directly to 0.5cm, after fermenting in 35℃for 24h, they produced 0.298g ethanol per gram dry sweet sorghum. In this way, It ethanol could be produced from 3.01t dry sweet sorghum. With this mode of alcoholic solid-state fermentation from wringed sweet sorghum, the cost of pressing juice was saved. In addition, its advantages included less fermentation residue, less energy consume and investment, lower operation cost, smaller room, less waste water and so on.Secondly, on the base of optimal fermentation conditions, the research on feed-batch fermentation was carried out. Adding new feed after 16h fermentation, then going on fermenting for 8h, the ethanol yield reached its maximum with a increase of 18.5 % than no feed-batch fermentation.Thirdly, in order to reduce the loss of energy, gas-stripping effect experiment was studied with CO₂ as carrier gas; 79.16% ethanol was obtained after gas-stripping and refrigeration. Ethanol yield wound increase a bit, when prolonging time and increasing temperature.Finally, classification using of sweet sorghum residue was studied. Fermentation residue of sweet sorghum was screened with 8 mesh screen, long fibred which contained 3.95%protein, whose digestion in vitro was 35.40% remained on the screen; and short fibred whose number was 36.37% and 43.59 % respectively, passed the screen. Because long fibred had good toughness, especially distinctly one another, it could be used to make paper. Short fibred had good wine smell, soft feeling and well dainty, so it could be used for feeding livestock. In this experiment, the sweet sorghum residue was made good use of so that it could reduce environment polluting.