Enzymatic hydrolysis, simultaneous saccharification and ethanol fermentation of oxalic acid pretreated giant reed (Arundo donax L.)

•Giant reed biomass has been pretreated with dilute oxalic acid.•Enzymatic hydrolysis and SSF have been optimized through RSM.•Enzymatic hydrolysis showed a glucan conversion of 95%.•Ethanol production using Schefferomyces (Pichia) stipitis CBS 6054 reached 18gl−1.•Maximum theoretical ethanol yield was 75%. Giant reed was evaluated for enzymatic hydrolysis and simultaneous saccharification and fermentation (SSF) using a commercial cellulase/β-glucosidase and Scheffersomyces (Pichia) stipitis CBS 6054 for ethanol production following dilute-oxalic acid pretreatment. A response surface methodology with two input parameters – severity factor (SF) and oxalic acid concentration (OA) – was employed to optimize both enzymatic hydrolysis and SSF. Xylan content after dilute-OA pretreatment decreased with increasing SF and OA; almost complete hydrolysis was observed when the harsher pretreatment conditions were used. Glucan and lignin content showed an opposite trend with respect to xylan content after dilute-OA pretreatment. Accordingly, enzymatic hydrolysis and ethanol production reached 95% of glucan conversion and 18gl−1 (75.3% of the maximum theoretical ethanol yield), respectively, with the pretreatment condition 4.05 SF and 5% OA w/w. Dilute-OA mediated pretreatment of giant reed followed by coupled saccharification and fermentation can be considered a promising methodology for second generation bioethanol production.