为实现玉米秸秆高效转化可发酵糖,提升玉米秸秆生产纤维素乙醇竞争力,对碱过氧化氢法预处理后高浓玉米秸秆半同步糖化发酵生产燃料乙醇的工艺进行了研究。建立底物浓度与酶解糖得率关系模型,以确定适宜的底物浓度。向预处理后的玉米秸秆中添加吐温20,考察其酶解过程特性,确定吐温20最适添加量。结果表明,酶解最适条件为:底物质量浓度200 g/L,吐温20添加量8%(ω)。在该条件基础上,对酵母种龄、吐温20对酵母发酵影响、半同步糖化发酵预酶解时间、半同步糖化发酵的时间、发酵温度进行了研究,确定了半同步糖化发酵的工艺条件为:种龄16 h,吐温20添加量5%(ω),预酶解时间9 h,半同步糖化发酵时间7 d,温度34 ℃。在最佳条件下,发酵7 d后,乙醇浓度达到23.64 g/L,乙醇转化率达到76.54%,较对照组(不添加吐温20)转化率提升3.41%。该工艺条件下能实现高浓玉米秸秆高效转化可发酵糖及乙醇的目的。
To convert corn stover to fermentable sugar efficiently and improve the competiveness of cellulosic ethanol, the optimal process of semi-simultaneous saccharification and fermentation (SSSF) for corn stover to produce fuel ethanol based on the alkaline hydrogen peroxide (AHP) pretreatment was investigated. The optimal biomass loading was confirmed by the relationship of biomass loading and sugar yields. Also, the optimal addition of Tween 20 was studied by adding it to AHP pretreated corn stover during enzymatic hydrolysis. The results showed that the optimal condition for enzymatic hydrolysis were as follow: 200 g/L of biomass loading and 8% (ω) of Tween 20 loading. Based on this condition, some parameters were investigated, the optimal conditions for SSSF were as follows: 5%(ω) of Tween 20 loading, the seed age of yeast was 16 h, the ending time of pre-enzymatic hydrolysis during SSSF was 10 h, the fermentation temperature was 34 ℃, and the time of SSSF was 7 d. Under these conditions, the final concentration of ethanol was 23.64 g/L, and the conversion rate was 76.54%. Compared to the control (without addition of Tween 20), the ethanol yield was improved by 3.41%. The results indicated that converting high solids corn stover could be converted to fermentable sugar and ethanol efficiently under this process. This study provided an efficient way for the industrial-scale production of cellulosic ethanol.