Harnessing Biohydrogen from Banana Fruit Rejects Through Photofermentation with Rhodopseudomonas palustris

The increasing global demand for fossil fuels has led to environmental challenges associated with greenhouse gas emissions and resource depletion. To address these issues, the use of renewable energy sources has become pivotal in reducing global reliance on fossil fuels. This study investigated banana fruit rejects (BFR) as a potential feedstock for biohydrogen production through photofermentation, employing Rhodopseudomonas palustris as the microbial culture medium. It aims to optimize the conditions for biohydrogen production, focusing on the hydraulic retention time (HRT) and pH level to maximize biohydrogen yield from this BFR. Before fermentation, the BFR was subjected to acid hydrolysis as a pretreatment step to increase its sugar content. By employing a central composite design of response surface methodology, the study seeks to determine the interaction between HRT and pH level and their influence on biohydrogen production, ultimately contributing to sustainable waste management and renewable energy generation. The findings of this study revealed that acid hydrolysis effectively raised the sugar content of BFR from 3 °Brix to 12 °Brix. Acid-hydrolyzed BFR could produce 4.44 L biohydrogen from a kilogram of BFR at optimized conditions: HRT of 60 h and a pH of 8. The response surface quadratic model exhibited the highest accuracy in predicting biohydrogen generation through photofermentation. Gas chromatography analysis of the produced biogas revealed the presence of oxygen, carbon dioxide, nitrogen, and biohydrogen gas - the highest significant fraction accounting 74% of the total biogas composition. Overall, this work successfully demonstrated the production of desired biohydrogen from BFR through photofermentation with Rhodopseudomonas palustris. The findings underscore the importance of optimizing process parameters to enhance biohydrogen yield, contributing to the development of environmentally friendly and renewable energy alternatives while reducing dependence on fossil fuels.