Sequential high gravity ethanol fermentation and anaerobic digestion of steam explosion and organosolv pretreated corn stover

摘要

The present work investigates the suitability of pretreated corn stover (CS) to serve as feedstock for high gravity (HG) ethanol production at solids-content of 24 wt%. Steam explosion, with and without the addition of H2SO4, and organosolv pretreated CS samples underwent a liquefaction/saccharification step followed by simultaneous saccharification and fermentation (SSF). Maximum ethanol concentration of ca. 76 g/L (78.3% ethanol yield) was obtained from steam exploded CS (SECS) with 0.2% H2SO4. Organosolv pretreated CS (OCS) also resulted in high ethanol concentration of ca. 65 g/L (62.3% ethanol yield). Moreover, methane production through anaerobic digestion (AD) was conducted from fermentation residues and resulted in maximum methane yields of ca. 120 and 69 mL/g volatile solids (VS) for SECS and OCS samples, respectively. The results indicated that the implementation of a liquefaction/saccharification step before SSF employing a liquefaction reactor seemed to handle HG conditions adequately.