Effect of headspace gas composition on carboxylates production in open-culture fermentation of corn stover

Darvekar, Pratik; Liang, Chao; Karim, M. Nazmul; Holtzapple, Mark T.

doi:10.1016/j.biombioe.2019.04.019

Cited by 10 publications

(11 citation statements)

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“…After 30 days of digestion, <0.1% hydrogen was detected. This is possibly because hydrogen, a reducing agent, is consumed in interspecies hydrogen transfer, which allows its chemical energy to be incorporated into other products like carboxylic acids 18 . Because iodoform was added to inhibit methanogenesis, no methane was detected during gas analysis.…”

Section: Resultsmentioning

confidence: 99%

“…This is possibly because hydrogen, a reducing agent, is consumed in interspecies hydrogen transfer, which allows its chemical energy to be incorporated into other products like carboxylic acids. 18 Because iodoform was added to inhibit methanogenesis, no methane was detected during gas analysis. Significant nitrogen was detected because it is used to purge the digesters when opened during periodic sampling.…”

Section: Gas Productionmentioning

confidence: 99%

“…After anaerobic digestion is complete, well‐developed gasification technologies can convert undigested lignin‐rich residues into hydrogen and process heat 17 . The hydrogen can be used to upgrade the carboxylate intermediates to hydrocarbon fuels, or it can be fed to the fermentor as a reducing agent 18 …”

Section: Introductionmentioning

confidence: 99%

“…17 The hydrogen can be used to upgrade the carboxylate intermediates to hydrocarbon fuels, or it can be fed to the fermentor as a reducing agent. 18 In a previous study, shock and alkaline pretreatment conditions were assessed using extracellular enzymes. 19 Enzymatic hydrolysis is rapid and precise, and therefore useful for screening multiple pretreatment conditions.…”

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confidence: 99%

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Assessment of corn stover pretreated with shock and alkali using methane‐arrested anaerobic digestion

Olokede

Hsu

Huang

et al. 2022

Biotechnology Progress

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Corn stover, an underutilized agricultural residue, is a promising lignocellulosic feedstock for producing biofuels. To fully utilize it, pretreatment is needed. Typically, pretreatments are rapidly assessed using extracellular enzymes that release sugars from cellulose and hemicellulose. In contrast, this study uses methane‐arrested anaerobic digestion (MAAD) to assess pretreatments. Although time consuming, MAAD is a more accurate assessment technique when lignocellulose is employed in the carboxylate platform, a promising approach that utilizes nearly all biomass components. Using recommended pretreatment conditions identified from a previous study, three corn stover pretreatments were compared using MAAD: (1) shock‐only, (2) NaOH‐only, and (3) shock + NaOH. Air‐dried sewage sludge was used as nutrient source. At 100 g/L initial substrate concentration, compared to untreated corn stover, shock‐only decreased conversion (amount of biomass digested) by 14%, NaOH‐only increased conversion by 82%, and shock + NaOH increased conversion by 104%. Using batch MAAD data, the continuum particle distribution model simulated four‐stage countercurrent fermentation. At an industrial non‐acid volatile solids (NAVS) concentration of 300 g/Lliq, for both NaOH‐only and shock + NaOH, the model predicts total carboxylic acid concentration of about 58 g/L and conversion of about 0.85 g NAVSdigested/g NAVSfed at liquid retention time of 35 days and volatile solid loading rate of 4 g/(Lliq⋅day). At this long solid residence time, shock is not necessary; however, with short solid residence times, shock acts synergistically to aid NaOH pretreatment. Shock treatment offers a way to reduce pretreatment costs without sacrificing pretreatment efficacy.

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Section: Resultsmentioning

confidence: 99%

Section: Gas Productionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Assessment of corn stover pretreated with shock and alkali using methane‐arrested anaerobic digestion

Olokede

Hsu

Huang

et al. 2022

Biotechnology Progress

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“…5 Headspace gas composition and pressure play a role in product formation and metabolic pathways preferentially used. However, most studies still focus on hydrogen production (Darvekar et al, 2019). According to Zhou (2018) and Sarkar (2017), low hydrogen pressure favors VFA formation.…”

Section: Introductionmentioning

confidence: 99%

Thermal and alkaline pre-treatments of inoculum halt methanogenesis and enables cheese whey valorization by batch acidogenic fermentation

Almeida

Mondini

Bruant

et al. 2023

Preprint

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Carboxylates like volatile fatty acids (VFAs) can be produced by acidogenic fermentation (AF) of dairy wastes like cheese whey, a massive residue produced at 160.67 million m3of which 42% are not valorized and impact the environment. In mixed-culture fermentations, selection pressures are needed to favor AF and halt methanogenesis. Inoculum pre-treatment was studied here as elective pressure for AF demineralized cheese whey in batch processes. Alkaline (NaOH, pH 8.0, 6 h) and thermal (90 °C for 5 min, ice-bath until 23 °C) pre-treatments, were tested together with batch operations run at initial pH 7.0 and 9.0, food-to-microorganism (F/M) ratios of 0.5 to 4.0 g COD g-1VS, and under pressurized and non-pressurized headspace, in experiments duplicated in two institutes. Acetic acid was highly produced (1.36 and 1.40 g CODAcOH L-1) at the expense of methanogenesis by combining a thermal pre-treatment of inoculum with a non-pressurized batch operation started at pH 9.0. Microbial communities comprised of VFAs and alcohol producers, such asClostridium,Fonticella, andIntestinimonas, and fermenters such asLongilineaandLeptolinea. Communities also presented the lipid-accumulating and bulk and foamingCandidatus Microthrixand the metanogenicMethanosaetaregardless of no methane production. An F/M ratio of 0.5 g COD g-1VS led to the best VFA production of 1,769.38 mg L-1. Overall, inoculum thermal pre-treatment, initial pH 9.0, and non-pressurized headspace acted as a selective pressure for halting methanogen and producing VFAs, valorizing cheese whey via batch acidogenic fermentation.

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Thermal and alkaline pre‐treatments of inoculum halt methanogenesis and enable cheese whey valorization by batch acidogenic fermentation

de Almeida,

Mondini,

Bruant

et al. 2024

J of Chemical Tech & Biotech

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BackgroundCarboxylates like volatile fatty acids (VFAs) can be produced by acidogenic fermentation (AF) of dairy wastes like cheese whey, a massive residue produced at 160.67 million m3 of which 42% are not valorized and impact the environment. In mixed‐culture fermentations, selection pressures can favor AF and halt methanogenesis. In this study, inoculum pre‐treatment was evaluated as a selective pressure for AF demineralized cheese whey in batches. Alkaline (NaOH, pH 8.0, 6 h) and thermal (90°C for 5 min, ice‐bath until 23°C) pre‐treatments, were tested with batch operations runs at initial pH 7.0 and 9.0, food‐to‐microorganism (F/M) ratios of 0.5 to 4.0 g COD g‐1 VS, and under pressurized and non‐pressurized headspace, in experiments duplicated in two different research institutes.ResultsAcetic acid was highly produced on both Unicamp and TU Delft samples (1.36 and 1.40 g CODAcOH L‐1, respectively), at the expense of methanogenesis by combining a thermal pre‐treatment of inoculum with a non‐pressurized batch operation started at pH 9.0. Microbial communities comprised of VFAs and alcohol producers, such as Clostridium, Fonticella, and Intestinimonas, and fermenters such as Longilinea and Leptolinea. Communities also presented the lipid‐accumulating and bulk and foaming Candidatus Microthrix and the metanogenic Methanosaeta regardless of no methane production. An F/M ratio of 0.5 g COD g‐1 VS led to the best VFA production of 1,769.4 mg L‐1.ConclusionOverall, inoculum thermal pre‐treatment, initial pH 9.0, and non‐pressurized headspace acted as a selective pressure for halting methanogenesis and producing VFAs, valorizing cheese whey via batch acidogenic fermentation.This article is protected by copyright. All rights reserved.

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Effect of headspace gas composition on carboxylates production in open-culture fermentation of corn stover

Cited by 10 publications

References 10 publications

Assessment of corn stover pretreated with shock and alkali using methane‐arrested anaerobic digestion

Assessment of corn stover pretreated with shock and alkali using methane‐arrested anaerobic digestion

Thermal and alkaline pre-treatments of inoculum halt methanogenesis and enables cheese whey valorization by batch acidogenic fermentation

Thermal and alkaline pre‐treatments of inoculum halt methanogenesis and enable cheese whey valorization by batch acidogenic fermentation

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