Gas mass transfer in syngas fermentation broths is enhanced by ethanol

Puiman, Lars; Elisiário, Marina P.; Crasborn, Lilo M.L.; Wagenaar, Liselot E.C.H.; Straathof, Adrie J. J.; Haringa, Cees

doi:10.1016/j.bej.2022.108505

Cited by 10 publications

(9 citation statements)

References 46 publications

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“…The ideal-mixing model suggests that an optimum q i could be obtained at a certain biomass concentration, but the exact biomass concentration remains difficult to be determined using the CFD models, considering the wide concentration distribution, the non-linear kinetics, and that iteratively running these models is very time-consuming. As there is less inhibition at higher c X , there could be a possibility of increasing gas conversion by supplying more gas, providing that coalescence remains suppressed by the broth components [31]. There is a large volumetric spread in the dissolved gas concentrations obtained by the CFD models.…”

Section: Influence Of Biomass Concentrationmentioning

confidence: 98%

“…In order to obtain a realistic mass transfer rate for industrial-scale syngas fermentation, spherical bubbles with constant diameter (3 mm) were assumed, based upon our previous work [4] (Equation ( 5)). Since coalescence could be suppressed by the presence of surfaceactive compounds (e.g., ethanol, salts) in syngas-to-ethanol fermentations, small bubbles can be obtained, leading to high mass transfer rates [18,31,38,39].…”

Section: Mass Transfer Modelmentioning

confidence: 99%

“…The volumetric mass transfer coefficient k L a of compound i is dependent on the superficial gas velocity and the stirrer speed [46] and was estimated by considering mass transfer enhancement by the broth composition ( f broth = 1.5; [31]), the temperature and the compound-specific diffusion coefficient in water (Equation ( 13)). The power input was estimated for a Rushton impeller with P 0 = N Po n 3 d 5 i and the geometry used [32,45].…”

Section: Design Of a Scale-down Simulatormentioning

confidence: 99%

“…The impact of gas (CO 2 ) production on the dissolved gas concentration gradients, and thus possible fluctuations for the microbe, was studied. We used our previous CFD model of an industrial-scale external-loop gas-lift reactor (EL-GLR) and our lab observations to develop and analyses lifelines representative for large-scale syngas fermentation [4,31].…”

Section: Introductionmentioning

confidence: 99%

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Downscaling Industrial-Scale Syngas Fermentation to Simulate Frequent and Irregular Dissolved Gas Concentration Shocks

et al. 2023

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In large-scale syngas fermentation, strong gradients in dissolved gas (CO, H2) concentrations are very likely to occur due to locally varying mass transfer and convection rates. Using Euler-Lagrangian CFD simulations, we analyzed these gradients in an industrial-scale external-loop gas-lift reactor (EL-GLR) for a wide range of biomass concentrations, considering CO inhibition for both CO and H2 uptake. Lifeline analyses showed that micro-organisms are likely to experience frequent (5 to 30 s) oscillations in dissolved gas concentrations with one order of magnitude. From the lifeline analyses, we developed a conceptual scale-down simulator (stirred-tank reactor with varying stirrer speed) to replicate industrial-scale environmental fluctuations at bench scale. The configuration of the scale-down simulator can be adjusted to match a broad range of environmental fluctuations. Our results suggest a preference for industrial operation at high biomass concentrations, as this would strongly reduce inhibitory effects, provide operational flexibility and enhance the product yield. The peaks in dissolved gas concentration were hypothesized to increase the syngas-to-ethanol yield due to the fast uptake mechanisms in C. autoethanogenum. The proposed scale-down simulator can be used to validate such results and to obtain data for parametrizing lumped kinetic metabolic models that describe such short-term responses.

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Section: Influence Of Biomass Concentrationmentioning

confidence: 98%

Section: Mass Transfer Modelmentioning

confidence: 99%

Section: Design Of a Scale-down Simulatormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Downscaling Industrial-Scale Syngas Fermentation to Simulate Frequent and Irregular Dissolved Gas Concentration Shocks

et al. 2023

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“…Organic substances inhibit the coalescence resulting in smaller bubbles. Recently, the latter has been demonstrated by [17] investigating the impact of ethanol in gas fermentation. Regarding the impact of AF, multiple mechanisms are considered in literature [18][19][20][21].…”

Section: Mass Transfer Calculationsmentioning

confidence: 99%

Revisiting Basics of k_La Dependency on Aeration in Bubble Columns: a Is Surprisingly Stable

Wild

Mast

2023

Chemie Ingenieur Technik

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Dedicated to Prof. Dr. Christian Wandrey on the occasion of his 80th birthday A comprehensive experimental characterization of a small-scale bubble column bioreactor (60 mL) is presented. Bubble size distribution (BSD), gas holdup, and k L a were determined for different types of liquids, relevant fermentation conditions and superficial gas velocities u G . The specific interfacial area a and liquid mass transfer coefficient k L have been identified independent of each other to unravel their individual impact on k L a. Results show that increasing u G leads to larger bubbles and higher gas holdup. As both parameters influence a in opposite ways, no increase of a with u G is found. Furthermore, k L increases with increasing bubble size outlining that improved oxygen transfer is not the result of higher a but of risen k L instead. The results build the foundation for further simulative investigations.

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A novel experimental method to determine substrate uptake kinetics of gaseous substrates applied to the carbon monoxide‐fermenting Clostridium autoethanogenum

Allaart,

Korkontzelos,

Sousa

et al. 2024

Biotech & Bioengineering

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Syngas fermentation has gained momentum over the last decades. The cost‐efficient design of industrial‐scale bioprocesses is highly dependent on quantitative microbial growth data. Kinetic and stoichiometric models for syngas‐converting microbes exist, but accurate experimental validation of the derived parameters is lacking. Here, we describe a novel experimental approach for measuring substrate uptake kinetics of gas‐fermenting microbes using the model microorganism Clostridium autoethanogenum. One‐hour disturbances of a steady‐state chemostat bioreactor with increased CO partial pressures (up to 1.2 bar) allowed for measurement of biomass‐specific CO uptake‐ and CO2 production rates (, ) using off‐gas analysis. At a pCO of 1.2 bar, a of −119 ± 1 mmol g−1X h−1 was measured. This value is 1.8–3.5‐fold higher than previously reported experimental and kinetic modeling results for syngas fermenters. Analysis of the catabolic flux distribution reveals a metabolic shift towards ethanol production at the expense of acetate at pCO 0.6 atm, likely to be mediated by acetate availability and cellular redox state. We characterized this metabolic shift as acetogenic overflow metabolism. These results provide key mechanistic understanding of the factors steering the product spectrum of CO fermentation in C. autoethanogenum and emphasize the importance of dedicated experimental validation of kinetic parameters.

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Gas mass transfer in syngas fermentation broths is enhanced by ethanol

Cited by 10 publications

References 46 publications

Downscaling Industrial-Scale Syngas Fermentation to Simulate Frequent and Irregular Dissolved Gas Concentration Shocks

Downscaling Industrial-Scale Syngas Fermentation to Simulate Frequent and Irregular Dissolved Gas Concentration Shocks

Revisiting Basics of k_La Dependency on Aeration in Bubble Columns: a Is Surprisingly Stable

A novel experimental method to determine substrate uptake kinetics of gaseous substrates applied to the carbon monoxide‐fermenting Clostridium autoethanogenum

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Gas mass transfer in syngas fermentation broths is enhanced by ethanol

Cited by 10 publications

References 46 publications

Downscaling Industrial-Scale Syngas Fermentation to Simulate Frequent and Irregular Dissolved Gas Concentration Shocks

Downscaling Industrial-Scale Syngas Fermentation to Simulate Frequent and Irregular Dissolved Gas Concentration Shocks

Revisiting Basics of kLa Dependency on Aeration in Bubble Columns: a Is Surprisingly Stable

A novel experimental method to determine substrate uptake kinetics of gaseous substrates applied to the carbon monoxide‐fermenting Clostridium autoethanogenum

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Product

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Revisiting Basics of k_La Dependency on Aeration in Bubble Columns: a Is Surprisingly Stable