Study On Ethanol Production By Ultra-low Temperature Superfine Grinding And Immobilized Cellulas Hydrolysis From Lignocellulose

Lignocellulose is a new available energy sources. There is great abundance of surplus plant material worldwide. Woody waste, i.e. wood chips, wood powder, and barks, is an un utilized plant biomass Furthermore, the conversion of woody waste into fuel materials such as ethanol and methane seems to be a new method for producing alternative energy. This paper studied that the pretreatment of the lingnocellulose, the immobilized cellulas hydrolyze lignocellulose and the process of ethanol fermentation.Investigation were carried out for several methods of pretreatment affected the hydrosis of lignocellulose, such as acid pretreatment, alkali pretreatment, superfine grinding pretreatment and ultra-low temperature superfine grinding pretreatment, there is no report so far for method of ultra-low temperature superfine grinding pretreatment. The result showed that the enzymolysis yield of acid pretreatment was lowest 6.58% and that of ultra-low temperature superfine grinding pretreatment was the highest 31.78% through comparing these extracting methods.To immobilize cellulases with the cross-linking method, studied the process of immobilized cellulases and the best conditions of immobilization, such as the weights of cellulose was 80 mg/g substracte, the concentration of glutaraldehyde was 7%, cross-linking time was 8 hours, immobilized cellulases activity was 1.18 u/g. Some characters of immobilized and native cellulases, such as Michaelis contant, optimum pH, and the effect of ionic strength, optimum, temperature stabilities to heat and repeat operation were studied and compared. Repeated 10 times hydrolysis processes by immobilized cellulas, the immobilized cellulase activity reduced by more than 50%.Studied the process of immobilized cellulas hydrolyze birch lignocellulose. The results showed that the optimal hydrolysis conditions were: temperature 45℃, pH value 5.0 and enzyme dosage 0.15 g/g substracte, the reducing sugar yield was 0.558 mg/mL.The results of ethanol fermentation on the cellulosic hydrolysate showed that: the optimal fermentation conditions were temperature 35℃, pH5.5, 15% yeast, glucose concentration 4%, flaker speed 150r/min, Ethanol yield reached 35.5% after 60h's fermentation. This demonstrated that it was feasible to produce ethanol in fermentation with the method of ultralow temperature superfine grinding and immobilized cellulas hydrolyze birch lignocellulose.