Difference between revisions of "Gas fermentation"
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== Process and technologies== | == Process and technologies== | ||
=== Production organisms === | === Production organisms === | ||
[[File:Reduktiver Acetyl-CoA-Weg.png|thumb| | [[File:Reduktiver Acetyl-CoA-Weg.png|thumb|402x402px|The reductive acetyl–CoA pathway]] | ||
A gas fermentation process depends on microorganisms that are able to digest gaseous carbon sources. Best known for this ability are acetogenic bacteria using the Wood-Ljungdahl pathway or acetyl-CoA pathway to fix and convert CO/CO<sub>2</sub> and | A gas fermentation process depends on microorganisms that are able to digest gaseous carbon sources. Best known for this ability are acetogenic bacteria using the Wood-Ljungdahl pathway or acetyl-CoA pathway to fix and convert CO/CO<sub>2</sub> and H<sub>2</sub> to biomass and products. They are able to synthesize useful products such as ethanol, butanol and 2,3-butanediol and they are anaerobes so need to be used in an anaerobic, oxygen-free atmosphere, fermentation setting. For commercial applications, mainly strains from ''Clostridium ljungdahlii'' and ''C. autoethanogenum'' are used.<ref name=":0" /><ref>{{Cite journal|title=Biotechnology for Chemical Production: Challenges and Opportunities|year=2016-03|author=Mark J. Burk, Stephen Van Dien|journal=Trends in Biotechnology|volume=34|issue=3|page=187–190|doi=10.1016/j.tibtech.2015.10.007}}</ref> Others acetogenic bacteria are in development as production organisms and there is a lot of activity in synthetic biology and genetic/metabolism engineering to modify these organisms. Additionally there are developments to integrate the metabolic pathways into well-known non-acetogenic organisms like ''Escherichia coli'' or yeasts to expand the options for fermentation processes.<ref name=":0" /> Besides, also aerobic bacteria can be used for gas fermentation. Aerobic hydrogen oxidizing bacteria, or Knallgas bacteria, are able fix CO<sub>2</sub> using H<sub>2</sub> as the electron donor and O<sub>2</sub> as the terminal electron acceptor using the Calvin-Benson-Bassham (CBB) cycle. Interestingly, this metabolism allows high biomass production and the synthesis of more complex products, including polyhydroxyalkanoates (PHA) bioplastics. As such, the Knallgas model organism ''Cupriavidus necator'', formerly known as ''Alcaligenes eutrophus'', can be used for the production of single-cell-protein (SCP) and natively accumulates polyhydroxybutyrate (PHB). | ||
=== Fermentation technology === | === Fermentation technology === | ||
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Depending on the gasified feedstock the syngas can have several impurities that lowers the productivity of the fermentation process or are toxic to the organisms. Even with gas-fermenting microorganisms' abilities to grow in the presence of low levels of impurities, some impurities necessitate near complete removal in a gas treatment by cyclone separators and filters from an operational, biological and/or product specificity perspective.<ref name=":0" /> | Depending on the gasified feedstock the syngas can have several impurities that lowers the productivity of the fermentation process or are toxic to the organisms. Even with gas-fermenting microorganisms' abilities to grow in the presence of low levels of impurities, some impurities necessitate near complete removal in a gas treatment by cyclone separators and filters from an operational, biological and/or product specificity perspective.<ref name=":0" /> | ||
In the gas fermentation step by itself the pre-treated and often cooled syngas is compressed and sparged into a bioreactor with the gas-fermenting microorganisms in an aqueous medium. Depending on the specific technologies a multitude of variables are to account for during gas fermentation. The yield and purity of the desired product depend e.g. on the | In the gas fermentation step by itself the pre-treated and often cooled syngas is compressed and sparged into a bioreactor with the gas-fermenting microorganisms in an aqueous medium. Depending on the specific technologies a multitude of variables are to account for during gas fermentation. The yield and purity of the desired product depend e.g. on the bioreactor design, agitation, gas composition and supply rate, pH, temperature, headspace pressure, oxidation-reduction potential (ORP), nutrients, and amount of foaming. As gas-fermenting microorganisms consume the gas, substrate availability can become rate-limiting and the bioreactor need to have a design that allows a high solubility of the gaseous substrates. In laboratory or small scale fermentation continuous stirred tank reactors (CSTR) offer excellent mixing and homogenous distribution of gas substrates to the microorganisms and are most commonly used. In industrial scale other types like bubble column, loop, and immobilized cell columns are preferred due to high energy demand of the stirring.<ref name=":0" /> | ||
The design of a gas fermentation unit requires special attention as it involves the use of potentially explosive gas mixtures and toxic gases. With respect to the former, it should be in compliance with ATEX (ATmosphères EXplosibles) safety regulations. This is especially important in case of aerobic gas fermetentations, when a gas mixutre containing H2 (highly flammable) and O2 is sparged into the bioreactor. | |||
After fermentation , product separation is required as post-treatment to separate the desired metabolic product from the fermentation broth. For this [[distillation]] systems are common to separate products such as ethanol and acetone. Other technologies to separate fermentation products from broth include liquid-liquid extraction, gas stripping, adsorption, perstraction, pervaporation, and vacuum distillation, and each of these separation technologies has their own benefits and drawbacks.<ref name=":0" /> | After fermentation , product separation is required as post-treatment to separate the desired metabolic product from the fermentation broth. For this [[distillation]] systems are common to separate products such as ethanol and acetone. Other technologies to separate fermentation products from broth include liquid-liquid extraction, gas stripping, adsorption, perstraction, pervaporation, and vacuum distillation, and each of these separation technologies has their own benefits and drawbacks.<ref name=":0" /> | ||
==Product== | ==Product== | ||
Products from a gas fermentation depend on the organism used and its specific metabolism. Examples can be different kinds of alcohols like ethanol, butanol or isobutanol, but also organic acids, proteins, hydrogen or bio-based polymers like | Products from a gas fermentation depend on the organism used and its specific metabolism. Examples can be different kinds of alcohols like ethanol, butanol or isobutanol, but also organic acids, proteins, hydrogen or bio-based polymers like polyhydroxyalkanoates (PHAs). | ||
==Technology providers== | ==Technology providers== | ||
=== Bio Base Europe Pilot Plant (BBEPP) === | |||
[http://www.bbeu.org/pilotplant/ Bio Base Europe Pilot Plant (BBEPP)] is a flexible and diversified pilot plant for the development and scale up of new, bio-based and sustainable processes. It is capable of development of new bioprocesses, optimization of existing processes and scale up of a broad variety of bio-based processes up to an industrial level (from 5L to 50m3 scale, depending on the process). It can perform the entire value chain, from the green resources up to the final product. | |||
BBEPP has built up a significant expertise on gas fermentation and cultivation of acetogenic and Knallgas bacteria through several private collaborations with Arcelor Mittal, e.g. Valorco project and in an ISPT project with Syngip, Arcelor Mittal and Dow. Although the content of these private projects is confidential, the general experience gained will be helpful in the work aimed for in the proposed work. In addition, BBEPP is also involved in several European funded consortium based gas fermentation projects. In the [https://biocon-co2.eu/ BIOCONCO2] project, BBEPP is responsible for the construction mobile gas fermentation unit to be put on site at waste gas emitters and to convert these CO<sub>2</sub>-rich gases into chemical building blocks. In the [https://biosfera-project.eu/ BIOSFERA] project, biogenic residues and wastes will be gasified and the syngas will be fermented using acetogenic bacteria to produce acetate which will be converted in a second fermentation process to bio-based triacylglycerides (TAGs). In the CO2SMOS project, biogenic CO<sub>2</sub> emissions and renewable H<sub>2</sub> are converted by innovative biotechnologica land intensified chemical conversion process to develop the production of several bio-based fine and commodity chemicals (2,3-butanediol, long chain dicarboxylic acids, benzene, cyclic carbonates and polyhydroxyalkanoates). | |||
=== Coskata === | === Coskata === | ||
Revision as of 08:18, 24 September 2021
| Technology | |
| |
| Technology details | |
| Name: | Gas fermentation |
| Category: | |
| Feedstock: | Gaseous carbon source (CO, CO2, methane) |
| Product: | several |
A gas fermentation is an industrial fermentation process that uses gaseous feedstock like methane, CO or CO2 together with hydrogen converted by a living organism to produce a specific product like ethanol, butanol or others. Gas fermentation is requires organisms that are able to use these kind of feedstock as main or single carbon source for their metabolism.
Feedstock
For a gas fermentation gaseous carbon sources are used as a feedstock. They can be delivered from a gasification of biomass or other organic materials (e.g. municipal solid waste, MSW) or directly be taken from a gas source like a biogas production, an fermentation, an industrial point source or directly from the atmosphere via a carbon capture technology.
Process and technologies
Production organisms
A gas fermentation process depends on microorganisms that are able to digest gaseous carbon sources. Best known for this ability are acetogenic bacteria using the Wood-Ljungdahl pathway or acetyl-CoA pathway to fix and convert CO/CO2 and H2 to biomass and products. They are able to synthesize useful products such as ethanol, butanol and 2,3-butanediol and they are anaerobes so need to be used in an anaerobic, oxygen-free atmosphere, fermentation setting. For commercial applications, mainly strains from Clostridium ljungdahlii and C. autoethanogenum are used.[1][2] Others acetogenic bacteria are in development as production organisms and there is a lot of activity in synthetic biology and genetic/metabolism engineering to modify these organisms. Additionally there are developments to integrate the metabolic pathways into well-known non-acetogenic organisms like Escherichia coli or yeasts to expand the options for fermentation processes.[1] Besides, also aerobic bacteria can be used for gas fermentation. Aerobic hydrogen oxidizing bacteria, or Knallgas bacteria, are able fix CO2 using H2 as the electron donor and O2 as the terminal electron acceptor using the Calvin-Benson-Bassham (CBB) cycle. Interestingly, this metabolism allows high biomass production and the synthesis of more complex products, including polyhydroxyalkanoates (PHA) bioplastics. As such, the Knallgas model organism Cupriavidus necator, formerly known as Alcaligenes eutrophus, can be used for the production of single-cell-protein (SCP) and natively accumulates polyhydroxybutyrate (PHB).
Fermentation technology
The overall gas fermentation process can be divided into four steps:[1]
- accumulation or generation of syngas
- gas pretreatment
- gas fermentation in a bioreactor
- product separation.
Depending on the gasified feedstock the syngas can have several impurities that lowers the productivity of the fermentation process or are toxic to the organisms. Even with gas-fermenting microorganisms' abilities to grow in the presence of low levels of impurities, some impurities necessitate near complete removal in a gas treatment by cyclone separators and filters from an operational, biological and/or product specificity perspective.[1]
In the gas fermentation step by itself the pre-treated and often cooled syngas is compressed and sparged into a bioreactor with the gas-fermenting microorganisms in an aqueous medium. Depending on the specific technologies a multitude of variables are to account for during gas fermentation. The yield and purity of the desired product depend e.g. on the bioreactor design, agitation, gas composition and supply rate, pH, temperature, headspace pressure, oxidation-reduction potential (ORP), nutrients, and amount of foaming. As gas-fermenting microorganisms consume the gas, substrate availability can become rate-limiting and the bioreactor need to have a design that allows a high solubility of the gaseous substrates. In laboratory or small scale fermentation continuous stirred tank reactors (CSTR) offer excellent mixing and homogenous distribution of gas substrates to the microorganisms and are most commonly used. In industrial scale other types like bubble column, loop, and immobilized cell columns are preferred due to high energy demand of the stirring.[1]
The design of a gas fermentation unit requires special attention as it involves the use of potentially explosive gas mixtures and toxic gases. With respect to the former, it should be in compliance with ATEX (ATmosphères EXplosibles) safety regulations. This is especially important in case of aerobic gas fermetentations, when a gas mixutre containing H2 (highly flammable) and O2 is sparged into the bioreactor.
After fermentation , product separation is required as post-treatment to separate the desired metabolic product from the fermentation broth. For this distillation systems are common to separate products such as ethanol and acetone. Other technologies to separate fermentation products from broth include liquid-liquid extraction, gas stripping, adsorption, perstraction, pervaporation, and vacuum distillation, and each of these separation technologies has their own benefits and drawbacks.[1]
Product
Products from a gas fermentation depend on the organism used and its specific metabolism. Examples can be different kinds of alcohols like ethanol, butanol or isobutanol, but also organic acids, proteins, hydrogen or bio-based polymers like polyhydroxyalkanoates (PHAs).
Technology providers
Bio Base Europe Pilot Plant (BBEPP)
Bio Base Europe Pilot Plant (BBEPP) is a flexible and diversified pilot plant for the development and scale up of new, bio-based and sustainable processes. It is capable of development of new bioprocesses, optimization of existing processes and scale up of a broad variety of bio-based processes up to an industrial level (from 5L to 50m3 scale, depending on the process). It can perform the entire value chain, from the green resources up to the final product.
BBEPP has built up a significant expertise on gas fermentation and cultivation of acetogenic and Knallgas bacteria through several private collaborations with Arcelor Mittal, e.g. Valorco project and in an ISPT project with Syngip, Arcelor Mittal and Dow. Although the content of these private projects is confidential, the general experience gained will be helpful in the work aimed for in the proposed work. In addition, BBEPP is also involved in several European funded consortium based gas fermentation projects. In the BIOCONCO2 project, BBEPP is responsible for the construction mobile gas fermentation unit to be put on site at waste gas emitters and to convert these CO2-rich gases into chemical building blocks. In the BIOSFERA project, biogenic residues and wastes will be gasified and the syngas will be fermented using acetogenic bacteria to produce acetate which will be converted in a second fermentation process to bio-based triacylglycerides (TAGs). In the CO2SMOS project, biogenic CO2 emissions and renewable H2 are converted by innovative biotechnologica land intensified chemical conversion process to develop the production of several bio-based fine and commodity chemicals (2,3-butanediol, long chain dicarboxylic acids, benzene, cyclic carbonates and polyhydroxyalkanoates).
Coskata
...
LanzaTech
...
INEOS Bio
...
Vlemish Institute of Technology (VITO)
...
VTT Technical Research Centre of Finland
...
Patents
Currently no patents have been identified yet.
References
- ↑ a b c d e f FungMin Liew, Michael E. Martin, Ryan C. Tappel, Björn D. Heijstra, Christophe Mihalcea, Michael Köpke, 2016-05-11: Gas Fermentation—A Flexible Platform for Commercial Scale Production of Low-Carbon-Fuels and Chemicals from Waste and Renewable Feedstocks. Frontiers in Microbiology, Vol. 7, . doi: https://doi.org/10.3389/fmicb.2016.00694
- ↑ Mark J. Burk, Stephen Van Dien, 2016-03: Biotechnology for Chemical Production: Challenges and Opportunities. Trends in Biotechnology, Vol. 34, (3), 187–190. doi: https://doi.org/10.1016/j.tibtech.2015.10.007