Enhanced CO2 Conversion to Acetate through Microbial Electrosynthesis (MES) by Continuous Headspace Gas Recirculation (original) (raw)
Related papers
Environmental Science & Technology Letters, 2015
Using carbon dioxide for bioproduction combines decreased greenhouse gas emissions with a decreased dependence on fossil carbon for production of multicarbon products. Microbial electrosynthesis (MES) enables this, using renewable energy to drive the reduction of CO 2 at the cathode of an electrochemical cell. To date, low product concentrations preclude cost-effective extraction during MES. Here we present an approach that couples production and recovery of acetate in a single, three-chamber reactor system. Acetate was produced at 61% Coulombic efficiency and fully recovered as an acidified stream containing up to 13.5 g L −1 (225 mM) acetic acid, the highest obtained thus far. In contrast to previous MES studies, a single separated acidic product was generated through in situ membrane electrolysis enabling further upgrading.
Electrodeposited Hybrid Biocathode-Based CO2 Reduction via Microbial Electro-Catalysis to Biofuels
Membranes
Microbial electrosynthesis is a new approach to converting C1 carbon (CO2) to more complex carbon-based products. In the present study, CO2, a potential greenhouse gas, was used as a sole carbon source and reduced to value-added chemicals (acetate, ethanol) with the help of bioelectrochemical reduction in microbial electrosynthesis systems (MES). The performance of MES was studied with varying electrode materials (carbon felt, stainless steel, and cobalt electrodeposited carbon felt). The MES performance was assessed in terms of acetic acid and ethanol production with the help of gas chromatography (GC). The electrochemical characterization of the system was analyzed with chronoamperometry and cyclic voltammetry. The study revealed that the MES operated with hybrid cobalt electrodeposited carbon felt electrode yielded the highest acetic acid (4.4 g/L) concentration followed by carbon felt/stainless steel (3.7 g/L), plain carbon felt (2.2 g/L), and stainless steel (1.87 g/L). The alc...
Chemical Engineering Journal, 2022
Microbial electrosynthesis (MES) has been highlighted as a means to valorize inorganic gaseous carbon, such as CO 2 , into value-added chemicals using electricity as the reducing power. Electrode-based electron transfer delivers respiratory electrons to a live-cell biocatalyst through a biofilm matrix or via electron shuttle molecules. The addition of artificial mediators, such as neutral red (NR) and 2-hydroxy-1,4-naphthoquinone (HNQ), increased acetate synthesis significantly, suggesting that these mediators improve the electron transport capability between the suspended cells and electrode. Regular media replacement also improves MES by adapting mediator-utilizing species in the reactor. MES without a mediator initially produced acetate at a reasonable rate (5.1 ± 0.2 mmol/l/day), but the rate became negligible in the later stage. In contrast, MES with NR or HNQ showed a higher acetate production rate (4.6 ± 0.4 vs. 7.4 ± 0.4 mmol/l/day, respectively) as the media replacement progressed. Confocal laser scanning microscopy and 3D imaging showed that the biofilm matrix consisted of live and dead cells, while the composition was different in the MES with and without a mediator. Microbial community analysis by next-generation sequencing (NGS) showed that acetogenic Acetobacterium (in suspension) and Sporomusa (in both suspension and biofilm) were dominant during the 96 days of operation. The biofilm and planktonic community interacted dynamically under MES conditions. This result provides a realistic model of biofilms and planktonic cells in the MES. The interaction of the suspended cells with the biofilmforming electrode via electron shuttles could improve volumetric acetate production and stabilize the MES performance.
Environmental Science & Technology
Microbial electrosynthesis (MES) and anaerobic fermentation (AF) are two biological processes capable of reducing CO2, CO and water into acetic acid, an essential industrial reagent. In this study, we evaluated investment and production costs of acetic acid via MES and AF, and compared them to industrial chemical processes: methanol carbonylation and ethane direct oxidation. Production and investment costs were found high-priced for MES (1.44 £/Kg, 1770 £/t) and AF (4.14 £/Kg, 1598 £/t) due to variable and fixed costs and low production yields (100 t/y) compared to methanol carbonylation (0.26 £/Kg, 261 £/t) and ethane direct oxidation (0.11 £/Kg, 258 £/t). However, integrating AF with MES would reduce the release of CO2, double production rates (200 t/y) and decrease investment costs by 9% (1366 £/t). This resulted into setting the production costs at 0.24 £/Kg which is currently market competitive (0.48 £/Kg). This economically feasible bioprocess produced molar flow rates of 4550 moles per day from MES and AF independently. Our findings offer a bright opportunity towards the use and scale-up of MES and AF for an economically viable acetic acid production process.
Fermentation
Microbial electrocatalysis reckons on microbes as catalysts for reactions occurring at electrodes. Microbial fuel cells and microbial electrolysis cells are well-known in this context; both prefer the oxidation of organic and inorganic matter for producing electricity. Notably, the synthesis of high energy-density chemicals (fuels) or their precursors by microorganisms using bio-cathode to yield electrical energy is called Microbial Electrosynthesis (MES), giving an exceptionally appealing novel way for producing beneficial products from electricity and wastewater. This review accentuates the concept, importance and opportunities of MES, as an emerging discipline at the nexus of microbiology and electrochemistry. Production of organic compounds from MES is considered as an effective technique for the generation of various beneficial reduced end-products (like acetate and butyrate) as well as in reducing the load of CO2 from the atmosphere to mitigate the harmful effect of greenhouse...
Recent developments and key barriers to microbial CO2 electrobiorefinery
Bioresource Technology, 2021
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Environmental Science & Technology, 2013
Microbial electrosynthesis is the biocathode-driven production of chemicals from CO 2 and has the promise to be a sustainable, carbon-consuming technology. To date, microbial electrosynthesis of acetate, the first step in order to generate liquid fuels from CO 2 , has been characterized by low rates and yields. To improve performance, a previously established acetogenic biocathode was operated in semi-batch mode at a poised potential of −590 mV vs SHE for over 150 days beyond its initial development. Rates of acetate production reached a maximum of 17.25 mM day −1 (1.04 g L −1 d −1) with accumulation to 175 mM (10.5 g L −1) over 20 days. Hydrogen was also produced at high rates by the biocathode, reaching 100 mM d −1 (0.2 g L −1 d −1) and a total accumulation of 1164 mM (2.4 g L −1) over 20 days. Phylogenetic analysis of the active electrosynthetic microbiome revealed a similar community structure to what was observed during an earlier stage of development of the electroacetogenic microbiome. Acetobacterium spp. dominated the active microbial population on the cathodes. Also prevalent were Sulf urospirillum spp. and an unclassified Rhodobacteraceae. Taken together, these results demonstrate the stability, resilience, and improved performance of electrosynthetic biocathodes following long-term operation. Furthermore, sustained product formation at faster rates by a carbon-capturing microbiome is a key milestone addressed in this study that advances microbial electrosynthesis systems toward commercialization.