Biohydrogen production from winery effluents: control of the homoacetogenesis through the headspace gas recirculation

Abstract

BACKGROUND: Fermentative hydrogen production has an inherent limitation caused by hydrogen-consuming metabolic pathways such as homoacetogenesis related to high hydrogen partial pressures. In this study, a strategy based on recirculating the headspace gas was applied to increase the hydrogen release from the liquid to the gas phase in an upflow anaerobic sludge blanket(UASB) reactor fed with winery effluents. The influence of the gas upflow recirculation velocity on hydrogen production, hydrogen consumption by homoacetogenesis, and microbial community structure was evaluated.RESULTS: Under the control condition (only liquid recirculation), the hydrogen productivity was as much as 22 mL H 2 L −1 h −1 . Conversely, the hydrogen productivity increased up to 62 mL H 2 L −1 h −1 when the reactor was operated with an upflow gas recirculation velocity of 28.6 m d −1 . The increase in mass transfer, due to the gas recirculation, produces a decrease (up to 70%) in the hydrogen consumption rate associated with homoacetogenesis. High-throughput 16s rDNA sequencing characterization showed that the gas recirculation strategy promoted the development of hydrogen-producing microorganisms related to Megasphaera elsdenii and decreased the abundance of hydrogen-consuming bacteria related to Clostridium carboxidivorans and C. ljungdahlii. CONCLUSION:The results indicated that headspace recirculation at gas upflow velocities higher than 17.8 m d −1 increased the hydrogen production rate concomitantly with the reduction of both the homoacetogenic activity and the abundance of H 2 -consuming bacteria. The study demonstrated that headspace recirculation could be a promising way to control homoacetogenesis, and therefore, to increase the biohydrogen productivity from complex substrates such as winery effluents. ABBREVIATIONS CODchemical oxygen demand CSTR continuous stirred tank reactor EtOH residual ethanol (mg COD L -1 ) HA homoacetogenic activity HAc acetic acid (mg COD L -1 ) HBu butyric acid (mg COD L -1 ) HCap caproic acid (mg COD L -1 ) HC-H hydrogen consumers by homoacetogenesis HP-C hydrogen producer by carbohydrates HP-LA hydrogen producers by lactic acid HPR hydrogen production rate HPr propionic acid (mg COD L -1 ) HRT hydraulic retention time HVal valeric acid (mg COD L -1 ) m mixing degree MEE missing electron equivalents OTUs operational taxonomic units t mix mixing time UASB upflow anaerobic sludge blanket WWs winery wastewater effluents Homoacetogenic activityThe acetate production by homoacetogenic activity (HA) was calculated using the stoichiometric relation of hydrogen, acetate, J Chem Technol Biotechnol 2020; 95: 544-552

Hydrogen and organic acid production from dark fermentation of sugarcane vinasse without buffers in mesophilic and thermophilic conditions

“…Thus, the increase of the H 2 % in the headspace (reaching 60–80%) resulted in the decrease of VHPR because of the inhibitory effect of the H 2 partial pressure. Another factor that may have impaired the hydrogen production performance is homoacetogenesis, which is a hydrogen‐consuming metabolic pathway that is also related to high hydrogen partial pressures 32 . Buitrón et al 32 .…”

“…Another factor that may have impaired the hydrogen production performance is homoacetogenesis, which is a hydrogen‐consuming metabolic pathway that is also related to high hydrogen partial pressures 32 . Buitrón et al 32 . used a strategy based on recirculating the headspace gas to increase the hydrogen release from the liquid to the gas phase in a UASB reactor fed with winery effluents and the hydrogen productivity increased from 22 to 62 mL‐H 2 L −1 h −1 .…”

Up-Flow Anaerobic Sludge Blanket (UASB) Technology for Energy Recovery: A Review on State-of-the-Art and Recent Technological Advances

“…The original UASB configuration was modified in a number of scientific studies to satisfy a particular purpose, such as producing hydrogen or VFA (rather than methane), or increasing reactor performances through the introduction of packing materials ( Table 4 ). UASB reactor, in fact, can be used also for bio-hydrogen production by inhibiting methanogenic bacteria through sludge thermal pre-treatment, acid-basic procedures or headspace gas recirculation [ 89 , 90 , 91 ]. Different substrates have been tested for bio-hydrogen production, including palm oil mill effluent, winery wastewater and synthetic media [ 89 , 90 , 91 ].…”

“…UASB reactor, in fact, can be used also for bio-hydrogen production by inhibiting methanogenic bacteria through sludge thermal pre-treatment, acid-basic procedures or headspace gas recirculation [ 89 , 90 , 91 ]. Different substrates have been tested for bio-hydrogen production, including palm oil mill effluent, winery wastewater and synthetic media [ 89 , 90 , 91 ]. Besides H 2 , waste-derived VFA, especially acetate, are valuable bio-refinery products that can be used as precursors to fuels and chemicals in different industrial sectors [ 92 ].…”

Three-stage process for tequila vinasse valorization through sequential lactate, biohydrogen and methane production

“…In this regard, this study aimed at exploiting the "unwanted" lactate type fermentation to efficiently produce bioH 2 , while bringing forth practical and economical operational advantages. Hence, this study contributes to the scarce information regarding the continuous lactate-derived bioH 2 production which can be useful in other DF systems treating distillery wastewater (Couto et al, 2020;Fuess et al, 2018), molasses (Freitas et al, 2020;Oliveira et al, 2020), food waste (Noblecourt et al, 2018;Santiago et al, 2019), cheese whey (Asunis et al, 2019), winery effluents (Buitrón et al, 2020), and hydrolysates of lignocellulosic biomass (Muñoz-Páez et al, 2020), whose composition is suitable to undergo the lactate type fermentation.…”