A review on the factors influencing biohydrogen production from lactate: The key to unlocking enhanced dark fermentative processes

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

“…This is indicative that the DF of TV was, to a significant extent, uncoupled from carbohydrates consumption. This uncoupling behavior can be well supported with the lactate-based hydrogen-producing pathways, which have been previously reviewed comprehensively in [10]. Indeed, the observed hydrogen production corroborated well with the consumption of lactate and acetate and the formation of butyrate.…”

“…DF is a complex process, and its efficiency depends on the substrate characteristics, culture conditions and biological factors [10]. Substrate is typically characterized in terms of pH, solids, carbohydrates, proteins, lipids, as well as micronutrients and putative toxic compounds.…”

“…While it is true that nutrient supplementation may lead to an enhanced DF process, this strategy may be prohibited for economic reasons at industrial levels. Regarding culture conditions, the most important operational parameters include temperature (including mesophilic, thermophilic, and even hyperthermophilic temperatures), pH (typically set between 5.5 and 6.0), oxidation-reduction potential (ORP), substrate-to-biomass ratio (S 0 /X 0 ), organic loading rate (OLR), and hydraulic retention time (HRT) [10]. Moreover, the type of reactor configuration strongly impacts the hydrogen production efficiency.…”

“…Moreover, the type of reactor configuration strongly impacts the hydrogen production efficiency. Different reactors have been reported in the literature, including anaerobic packed-bed reactor (AnPBR), anaerobic structured-bed reactor (AnSTBR), anaerobic fluidized-bed reactor (AnFBR), expanded granular sludge bed reactor (EGSB), up-flow anaerobic sludge blanket reactor (UASB), anaerobic sequencing batch reactor (AnSBR), continuously stirred tank reactor (CSTR) [10], and, more recently, dynamic membrane reactors (DMBR) [11,12]. Among them, the CSTR is perhaps the most widely used reactor configuration to produce biohydrogen via DF due to easy operation and control, as well as owing to its flexibility to operate under suspended and attached biomass configurations; however, DMBRs have sustained very high hydrogen productivities using model substrates [11,13,14], and even more complex ones such as algal biomass [12].…”

“…Similarly, Toledo-Alarcón et al (2020) reported that the heat-shock pretreatment was advantageous over the aeration one using glycerol as the substrate [17]. However, the heat-shock pretreatment decreases the bacterial diversity and is not selective enough to distinguish between desirable and undesirable microorganisms [10].…”