Bioconversion of pine stumps to ethanol: pretreatment and simultaneous saccharification and fermentation

The technical viability was investigated for the conversion of stumps to value-added products via a chain of pretreatments and simultaneous saccharification and fermentation (SSF) steps to obtain bioethanol. Sequential steam explosion (SE), organosolv (OS) pretreatment and soda-anthraquinone pulping (Na/AQ) were performed resulting in an unbleached pulp (UBP), which was successfully converted via SSF to bioethanol with concentrations up to 79 g l , which corresponds to a conversion yield of 97% and productivity of 1.09 g l h at 15% total solids. Accordingly, delignification steps by oxygen bleaching are not necessary for bioethanol production. Different industrial softwood (SW) pulps were also tested as reference materials. Total lignin contents up to 4.5% in SW-based pulps had no adverse effects on SSF efficiency.