Co-fermentation of sugar-alcohol industry waste to produce hydrogen and value-added metabolites

The research focused on optimizing hydrogen production through the co-fermentation of three sugar-alcohol industry residues, sugarcane bagasse (SCB), filter cake (FC), and sugarcane vinasse (SCV). Batch assays were performed using enzymatically pretreated SCB (23.4 g·L−1) combined with varying concentrations of FC (7.9–37.7 g·L−1) and SCV (8.3–31.7 g COD·L−1). A mixed microbial culture bioaugmented with Clostridium butyricum was employed as the inoculum. In the process optimization the highest hydrogen yield (3239.78 mL·L−1) was achieved under conditions of 33.1 g·L−1 FC and 28.3 g COD·L−1 SCV, along with the production of 7132.8 mg·L−1 of valuable organic acids and solvents. Additionally, SCV at higher concentrations (31.7 g COD·L−1) favored homoacetogenesis, leading to an acetic acid accumulation of 7526.8 mg·L−1. Microbial community analysis by 16S rRNA sequencing revealed the dominance of Clostridium, Caproiciproducens, Anaerotruncus, Cellulosilyticum, and members of Lachnospiraceae, whose inferred functional genes included those encoding endoglucanase, xylanase, arabinofuranosidase, and lignin-degrading peroxidases. The findings highlight the potential of integrated bioconversion of sugar-alcohol industry residues to improve hydrogen and bioproduct generation, supporting more sustainable waste management and renewable energy production.