Dark Fermentation Process Response to the Use of Undiluted Tequila Vinasse without Nutrient Supplementation

The technical feasibility of valorizing tequila vinasse (TV), a wastewater with high pollution potential, through the production biogenic hydrogen via dark fermentation, has long been proven in diverse lab-scale reactors that were operated either batch or continuous mode. However, such systems have mainly tested diluted streams and nutrient supplementation, hindering techno-economic attractiveness TV-to-hydrogen concept at large scale. In this study, producing from high-strength undiluted TV no added extra nutrients was evaluated under mesophilic conditions. Additionally, use two different acidogenic inocula obtained by heat heat-aeration pretreatment investigated to get greater understanding effect inoculum type on process. results showed utilized herein contained macro- micro-nutrients enough support hydrogenogenic activity both cultures, entailing average yields 2.4–2.6 NL H2/L maximum rates 1.4–1.9 H2/L-d. Interestingly, consumption lactate acetate concomitant butyrate observed as main hydrogen-producing route regardless inoculum, pointing out relevance lactate-driven fermentative Clostridium beijerinckii ascertained key bacteria, but only association microorganisms belonging genera Enterobacter Klebsiella, revealed phylogenetic analyses.