Enhanced butanol production from ammonium sulfite pretreated wheat straw by separate hydrolysis and fermentation and simultaneous saccharification and fermentation

[Display omitted] Wheat straw (WS) was pretreated by ammonium sulfite (AS) for efficient acetone-butanol-ethanol (ABE) production by Clostridium acetobutylicum ATCC 824. Spent liquor containing the amides has the potential to be used for slow-release fertilizer production, and the solid fraction was readily for ABE fermentation. Compared to the results of separate hydrolysis and fermentation (SHF), relative higher ABE titer and yield were achieved in simultaneous saccharification and fermentation (SSF) using different level of AS pretreated WS (6%, 7.5%, 9% and 10.5%, w/v). As biomass loading in SHF increased from 6% to 10.5%, ABE (butanol) titer increased from 12.28 (7.52) to 17.75 (11.25) g/L, with ABE (butanol) yield reducing from 161 (98) to 133 (84) g/kg raw WS. For SSF, the maximum ABE (butanol) titer was obtained from 9% biomass loading. As biomass loading increased from 6% to 9%, ABE (butanol) titer increased from 17.13 (9.50) to 19.83 (12.64) g/L, with ABE (butanol) yield reducing from 224 (1 2 4) to 173 (1 1 0) g/kg raw WS. This study suggested that ABE production by SSF is viable to be conducted using AS pretreated WS.