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

Abstract

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

Food waste to bioenergy: current status and role in future circular economies in Indonesia

“…Several methods can be applied to generate biohydrogen, including electrodialysis, which can remove the VFAs in food waste composition (Hassan et al, 2019); fermentation via granular microbial preparation suitable for liquid food waste (Hovorukha et al, 2021); non-catalytic and catalytic steam and gasification which involve complex chemical mechanisms (Valizadeh et al, 2021). Other potential methods for biohydrogen production include photo fermentation (PF) (Azwar et al, 2014;Budiman and Wu, 2018); dark fermentation (DF) (Budiman and Wu, 2018;Rodríguez-Reyes et al, 2021); photo-dark fermentation, biophotolysis of green microalgae and cyanobacteria, or electrochemical and bio-electrochemical processes (Budiman and Wu, 2018). Among these conversion technologies, Balat and Kırtay (2010) reported that biomass gasification offers the easiest and most economical route for producing renewable hydrogen.…”

“…Among these conversion technologies, Balat and Kırtay (2010) reported that biomass gasification offers the easiest and most economical route for producing renewable hydrogen. However, alternative studies have emphasized that PF and/or DF is considered the most widely adopted approach due to its relatively low-cost and energy-saving technology (Budiman and Wu, 2018;Cappai et al, 2018;Rodríguez-Reyes et al, 2021). PF is a fermentative process involves photosynthetic microorganisms and directly converts organic materials to hydrogen (Kucharska et al, 2021).…”