In-situ extraction of microbial electrosynthesis products

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Membrane electrolysis assisted gas fermentation for enhanced acetic acid production

Gas fermentation has rapidly emerged as a commercial technology for the production of low-carbon fuels and chemicals from (industrial) CO and/or CO2-rich feedstock gas. Recent advances in using CO2 and H-2 for acetic acid production demonstrated that high productivity and substrate utilization are achievable. However, the costly constant addition of base and the energy-intensive nature of conventional recovery options (e.g., distillation) need to be overcome to drive organic acid production forward. Recently, membrane electrolysis has been presented as a technology that enables for the direct extraction of carboxylates across an anion exchange membrane (AEM) into a clean and low pH concentrate stream. Continuous in-situ extraction of acetate directly from the catholyte of a microbial electrosynthesis reactor showed that membrane electrolysis allows pure product recovery while improving productivity. Here we demonstrate that the system can be further enhanced through additional input of electrolytic hydrogen, produced at higher energetic efficiency while improving the overall extraction efficiency. A gas-lift reactor was used to investigate the hydrogen uptake efficiency at high hydrogen loading rates. During stable operation acetate transport across the membrane accounted for 31% of the charge balancing, indicating that the use of external H-2 can lead to a more efficient use of the extraction across the membrane. By coupling membrane electrolysis with the gas fermentation reactor the pH decrease associated with H-2/CO2 fermentations could be prevented, resulting in a stable and zero-chemical input process (except for the CO2). This now enables us to produce more than 0.6 M of acetic acid, a more attractive starting point toward further processing

Membrane Electrolysis Assisted Gas Fermentation for Enhanced Acetic Acid Production

Gas fermentation has rapidly emerged as a commercial technology for the production of low-carbon fuels and chemicals from (industrial) CO and/or CO2-rich feedstock gas. Recent advances in using CO2 and H2 for acetic acid production demonstrated that high productivity and substrate utilization are achievable. However, the costly constant addition of base and the energy-intensive nature of conventional recovery options (e.g., distillation) need to be overcome to drive organic acid production forward. Recently, membrane electrolysis has been presented as a technology that enables for the direct extraction of carboxylates across an anion exchange membrane (AEM) into a clean and low pH concentrate stream. Continuous in-situ extraction of acetate directly from the catholyte of a microbial electrosynthesis reactor showed that membrane electrolysis allows pure product recovery while improving productivity. Here we demonstrate that the system can be further enhanced through additional input of electrolytic hydrogen, produced at higher energetic efficiency while improving the overall extraction efficiency. A gas-lift reactor was used to investigate the hydrogen uptake efficiency at high hydrogen loading rates. During stable operation acetate transport across the membrane accounted for 31% of the charge balancing, indicating that the use of external H2 can lead to a more efficient use of the extraction across the membrane. By coupling membrane electrolysis with the gas fermentation reactor the pH decrease associated with H2/CO2 fermentations could be prevented, resulting in a stable and zero-chemical input process (except for the CO2). This now enables us to produce more than 0.6 M of acetic acid, a more attractive starting point toward further processing

Electrical current is more than hydrogen during microbial electrosynthesis and electrofermentation

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Waste-derived volatile fatty acids as carbon source for added-value fermentation approaches

The establishment of a sustainable circular bioeconomy requires the effective material recycling from biomass and biowaste beyond composting/fertilizer or anaerobic digestion/bioenergy. Recently, volatile fatty acids attracted much attention due to their potential application as carbon source for the microbial production of high added-value products. Their low-cost production from different types of wastes through dark fermentation is a key aspect, which will potentially lead to the sustainable production of fuels, materials or chemicals, while diminishing the waste volume. This article reviews the utilization of a volatile fatty acid platform for the microbial production of polyhydroxyalkanoates, single cell oil and omega-3 fatty acids, giving emphasis on the fermentation challenges for the efficient implementation of the bioprocess and how they were addressed. These challenges were addressed through a research project funded by the European Commission under the Horizon 2020 programme entitled 'VOLATILE-Biowaste derived volatile fatty acid platform for biopolymers, bioactive compounds and chemical building blocks'.This work was supported by the European project 'Volatile-Biowaste-derived volatile fatty acid platform for biopolymers, bioactive compounds and chemical building blocks' and has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement number 720777

Waste-derived volatile fatty acids as carbon source for added-value fermentation approaches

The establishment of a sustainable circular bioeconomy requires the effective material recycling from biomass and biowaste beyond composting/fertilizer or anaerobic digestion/bioenergy. Recently, volatile fatty acids attracted much attention due to their potential application as carbon source for the microbial production of high added-value products. Their low-cost production from different types of wastes through dark fermentation is a key aspect, which will potentially lead to the sustainable production of fuels, materials or chemicals, while diminishing the waste volume. This article reviews the utilization of a volatile fatty acid platform for the microbial production of polyhydroxyalkanoates, single cell oil and omega-3 fatty acids, giving emphasis on the fermentation challenges for the efficient implementation of the bioprocess and how they were addressed. These challenges were addressed through a research project funded by the European Commission under the Horizon 2020 programme entitled ‘VOLATILE—Biowaste derived volatile fatty acid platform for biopolymers, bioactive compounds and chemical building blocks’.This work was supported by the European project ‘VolatileBiowaste-derived volatile fatty acid platform for biopolymers, bioactive compounds and chemical building blocks’ and has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement number 720777

Increased concentration and current efficiency for in situ extraction of acetic acid in microbial electrosynthesis from CO2

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