Bioethanol Production from Spent Shiitake (Lentinula edodes) Mushroom Medium by Oxalic Acid Pretreatment

In this study, oxalic acid pretreatment of spent mushroom medium was performed depending on combined severity factor (CSF) to produce bioethanol. Glucose was the most abundant compound in the hydrolysate. The degradation rate of biomass was gradually increased by increasing the CSF during pretreatment. The highest ethanol production from hydrolysate was 2.79 g/L at CSF 1.89 (30 min, 82 mM oxalic acid) after 72 h fermentation. The fermentation inhibitor concentration increased by increasing the CSF. In the simultaneous saccharification and fermentation (SSF), the highest ethanol yield was 35.86% at CSF 2.18 (58 min, 82 mM oxalic acid). The optimal pretreatment condition for bioethanol production from the hydrolysate and pretreated biomass was CSF 1.89 (8.64 g/L).