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

Abstract

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.