Biohydrogen and methane production via silage-based dark co-fermentation using vinasse and filter cake

Vinasse and filter cake (FC) are promising substrates for hydrogen (H₂) production via dark fermentation. Silage, an anaerobic storage technique, helps break down macromolecules into simpler ones like xylose, fructose, and glucose. This study evaluated different ensiling durations (0, 20, 40, 80, and 100 days) on FC and its co-fermentation with sugarcane vinasse for H₂ production, using the digestate for methane (CH₄) production. The inoculum underwent an acid pretreatment to select H₂-producing bacteria. The 40-day ensiling period yielded the best H₂ performance (95 NmLH₂ gVS⁻¹, 43 % H₂ concentration). Longer durations (80 and 100 days) were inefficient. The main metabolic pathways for H₂ production were acetic and butyric acid production. The best CH₄ yield was from 20-day silage (311 NmLCH₄ gVS⁻¹). Predominant microorganisms were Firmicutes and Actinobacteria. Ensiling effectively pre-treats for H₂ and CH₄ production, improving yield, and efficiency.