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Improvement of dry simultaneous saccharification and fermentation of rice straw to high concentration ethanol by sodium carbonate pretreatment
- Molaverdi, Maryam, Karimi, Keikhosro, Mirmohamadsadeghi, Safoora
- Energy 2019 v.167 pp. 654-660
- crystal structure, ethanol, fermentation, glucose, hydrolysis, mixing, rice straw, saccharification, sodium carbonate
- Ethanol at high concentration was produced from rice straw pretreated with sodium carbonate through dry simultaneous saccharification and fermentation (DSSF). A high concentration of ethanol was obtained without mechanical mixing, an increase in fermentation time, and pre-hydrolysis. The most important influencing factors, including pretreatment time (3–10 h), enzyme loading (5–40 FPU/g substrate), solid loading (15–30 wt %), and DSSF reaction time (48–120 h), were investigated on dry hydrolysis and DSSF. An increase in pretreatment time from 3 to 10 h improved ethanol concentration from 55.1 to 67.7 g/L, obtained through DSSF at 20% solid loading and 10 FPU/g substrate. A glucose concentration as high as 124.6 g/L was obtained from the hydrolysis of the straw treated for 5 h. The highest total sugar and ethanol concentration were 137.3 g/L and 83.1 g/L for the treated straw, while they were 65.2 g/L and 38.6 g/L for the untreated ones, respectively, obtained by hydrolysis and DSSF at 30% solid loading. Changes associated with pretreatment, i.e., composition, crystallinity, and microscopic structure of untreated and treated straws, were investigated to find the reason for the improved hydrolysis and DSSF.