木薯纤维素乙醇发酵的纤维素酶成本评价

Evaluation of the cellulase cost during the cassava cellulose ethanol fermentation process

摘要:

木薯中的纤维素成分约占木薯干重的10％ (W/W)。文中以木薯燃料乙醇生产的木薯纤维素酒渣为原料，从纤维素酶成本角度评估了三种利用木薯纤维素组分发酵生产乙醇的方法，包括木薯纤维素酒渣的直接糖化和乙醇发酵、木薯纤维素酒渣预处理后的糖化与乙醇发酵、木薯乙醇发酵中同步淀粉与纤维素糖化以及乙醇发酵。结果表明，前两种方法的纤维素利用效率不高，酶成本分别达到13 602、11 659元/吨乙醇。第三种方法，即在木薯乙醇发酵过程同时加入糖化酶和纤维素酶，进行同步淀粉与纤维素糖化，进而进行乙醇发酵，木薯纤维素乙醇的收益最高。发酵结束时的乙醇浓度从101.5 g/L提高到107.0 g/L，纤维素酶成本为3 589元/吨乙醇。此方法利用木薯纤维素与木薯淀粉同时进行，不会带来额外的设备及操作投入，酶成本低于产品乙醇价格，可实现盈利，因此第三种方法为木薯纤维用于乙醇发酵的最适方法，本研究结果将为木薯乙醇产业深度利用木薯纤维提供依据。

Abstract:

Cellulose takes nearly 10% (W/W) dry weight of cassava tubers. In this study, the cellulase cost of different ethanol fermentation from cassava cellulose was evaluated. The processes include the direct saccharification and fermentation of original cassava cellulose residues, the direct saccharification and fermentation of pretreated cassava cellulose residues, and the simultaneous co-saccharification and fermentation of cassava starch and cassava cellulose. The results show that the cassava cellulose utilization in the first two processes were low with the enzyme cost of 13 602 and 11?659 RMB Yuan per tone of ethanol, respectively. In the third process, the final ethanol concentration increased from 101.5 g/L to 107.0 g/L when cassava cellulose and cassava starch were saccharified simultaneously. Comparing to the first two processes, the third one demonstrated the lowest enzyme cost at 3 589 RMB Yuan per ton of ethanol, which was less than the ethanol price and no additional equipment and operation cost input were added. The conclusion provided a practical way of cassava cellulose utilization in cassava ethanol industry.