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Difference between revisions of "Gas fermentation"
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==Feedstock== | ==Feedstock== | ||
For a gas fermentation gaseous carbon sources are used as a feedstock. They can be delivered from a [[gasification]] of biomass or other materials or directly be taken from a gas source like a [[Anaerobic digestion|biogas production]], an [[industrial fermentation|fermentation]], an industrial point source or directly from the atmosphere via a carbon capture technology. | 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 [[Anaerobic digestion|biogas production]], an [[industrial fermentation|fermentation]], an industrial point source or directly from the atmosphere via a carbon capture technology. | ||
== Process and technologies == | == Process and technologies== | ||
The overall gas fermentation process can be divided into four steps:<ref name=":0">{{Cite journal|title=Gas Fermentation—A Flexible Platform for Commercial Scale Production of Low-Carbon-Fuels and Chemicals from Waste and Renewable Feedstocks|year=2016-05-11|author=FungMin Liew, Michael E. Martin, Ryan C. Tappel, Björn D. Heijstra, Christophe Mihalcea, Michael Köpke|journal=Frontiers in Microbiology|volume=7|doi=10.3389/fmicb.2016.00694}}</ref> | |||
# 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.<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 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" /> | |||
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== | ||
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==Technology providers== | ==Technology providers== | ||
=== LanzaTech === | ===LanzaTech=== | ||
=== | ===INEOS Bio=== | ||
===XYZ=== | ===XYZ=== | ||