Main content area

Soaking Pretreatment of Corn Stover for Bioethanol Production Followed by Anaerobic Digestion Process

Zuo, Zhuang, Tian, Shen, Chen, Zebing, Li, Jia, Yang, Xiushan
Applied biochemistry and biotechnology 2012 v.167 no.7 pp. 2088-2102
Scheffersomyces stipitis, anaerobic digestion, biomass, biorefining, capital, corn stover, digestibility, enzymatic hydrolysis, ethanol, ethanol production, fermentation, glucose, lignin, methane, methane production, saccharification, soaking, xylose
The production of ethanol and methane from corn stover (CS) was investigated in a biorefinery process. Initially, a novel soaking pretreatment (NaOH and aqueous-ammonia) for CS was developed to remove lignin, swell the biomass, and improve enzymatic digestibility. Based on the sugar yield during enzymatic hydrolysis, the optimal pretreatment conditions were 1 % NaOH + 8 % NH4OH, 50°C, 48 h, with a solid-to-liquid ratio 1:10. The results demonstrated that soaking pretreatment removed 63.6 % lignin while reserving most of the carbohydrates. After enzymatic hydrolysis, the yields of glucose and xylose were 78.5 % and 69.3 %, respectively. The simultaneous saccharification and fermentation of pretreated CS using Pichia stipitis resulted in an ethanol concentration of 36.1 g/L, corresponding only to 63.3 % of the theoretical maximum. In order to simplify the process and reduce the capital cost, the liquid fraction of the pretreatment was used to re-soak new CS. For methane production, the re-soaked CS and the residues of SSF were anaerobically digested for 120 days. Fifteen grams CS were converted to 1.9 g of ethanol and 1337.3 mL of methane in the entire process.