Stirring the Hydrogen and Butanol production from Enset Fiber via Simultaneous Saccharification and Fermentation (SSF) process

Abstract

Abstract Background Replacing fossil fuels with biofuels such as hydrogen and butanol has the potential to reduce carbon emissions and improve the sustainability of the energy system. Enset fiber is a promising feedstock to produce these biofuels. Clostridium saccharoperbutylacetonicum DSM 14923 can produce hydrogen and butanol simultaneously; however, to achieve the best results, each product requires different fermentation conditions. This study aimed to optimize process parameters for the simultaneous saccharification and fermentation (SSF) process to produce hydrogen and butanol from Enset fiber, and to investigate the impact of pH control in the SSF process in the bioreactor. Results The SSF process in bottles resulted in a elevated butanol concentration of 11.36 g/L with a yield of 0.23 g/g and a productivity of 0.16 g/L− 1h− 1 at the optimal process parameters of 5% (w/v) substrate loading, 16 FPU/g cellulase loading, and 100 rpm agitation speed from pretreated Enset fiber. A comparable result was observed in the bioreactor during the pH-uncontrolled SSF process; however, the butanol productivity decreased to 0.095 g/L− 1h− 1. Furthermore, the pre-hydrolysis simultaneous saccharification and fermentation (PSSF) process in the bioreactor with a 7% (w/v) substrate loading led to the highest butanol concentration and productivity of 12.84 g/L and 0.104 g/L− 1h− 1 respectively. By further optimizing the SSF process, we achieved 442.57 mmol of hydrogen with a yield of 198.27 mL/g-Enset fiber in the bioreactor under the optimal conditions of temperature 37°C, initial pH 8.0 and atmospheric pressure. Conclusion In this study, a scalable process for both products was developed to achieve similar results to bottle-scale experiments, indicating potential applicability on an industrial scale. This is the first study to combine C. saccharoperbutylacetonicum and Enset fiber for the SSF process and contributes to the development of sustainable energy sources.