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American Society for Testing and Materials

Microbial fuel cells: From fundamentals to applications. A review

Artificial photosynthetic systems can store solar energy and chemically reduce CO2. We developed a hybrid water splitting–biosynthetic system based on a biocompatible Earth-abundant inorganic catalyst system to split water into molecular hydrogen and oxygen (H2 and O2) at low driving voltages. When grown in contact with these catalysts, Ralstonia eutropha consumed the produced H2 to synthesize biomass and fuels or chemical products from low CO2 concentration in the presence of O2. This scalable system has a CO2 reduction energy efficiency of ~50% when producing bacterial biomass and liquid fusel alcohols, scrubbing 180 grams of CO2 per kilowatt-hour of electricity. Coupling this hybrid device to existing photovoltaic systems would yield a CO2 reduction energy efficiency of ~10%, exceeding that of natural photosynthetic systems.

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Water splitting–biosynthetic system with CO2 reduction efficiencies exceeding photosynthesis

Environmental pollution from hazardous waste materials, organic pollutants and heavy metals, has adversely affected the natural ecosystem to the detriment of man. These pollutants arise from anthropogenic sources as well as natural disasters such as hurricanes and volcanic eruptions. Toxic metals could accumulate in agricultural soils and get into the food chain, thereby becoming a major threat to food security. Conventional and physical methods are expensive and not effective in areas with low metal toxicity. Bioremediation is therefore an eco-friendly and efficient method of reclaiming environments contaminated with heavy metals by making use of the inherent biological mechanisms of microorganisms and plants to eradicate hazardous contaminants. This review discusses the toxic effects of heavy metal pollution and the mechanisms used by microbes and plants for environmental remediation. It also emphasized the importance of modern biotechnological techniques and approaches in improving the ability of microbial enzymes to effectively degrade heavy metals at a faster rate, highlighting recent advances in microbial bioremediation and phytoremediation for the removal of heavy metals from the environment as well as future prospects and limitations. However, strict adherence to biosafety regulations must be followed in the use of biotechnological methods to ensure safety of the environment.

https://www.mdpi.com/1660-4601/14/12/1504/pdf

Microbial and Plant-Assisted Bioremediation of Heavy Metal Polluted Environments: A Review

Recent advances in the use of different substrates in microbial fuel cells toward wastewater treatment and simultaneous energy recovery

Applications of biochar in redox-mediated reactions.

Engineering electrodes for microbial electrocatalysis

Microbial electrosynthesis from CO2: forever a promise?

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 CO2 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.

Integrated Production, Extraction, and Concentration of Acetic Acid from CO2 through Microbial Electrosynthesis

Biochars have gathered considerable interest for agronomic and engineering applications. In addition to their high sorption ability, biochars have been shown to accept or donate considerable amounts of electrons to/from their environment via abiotic or microbial processes. Here, we measured the electron accepting (EAC) and electron donating (EDC) capacities of wood-based biochars pyrolyzed at three different highest treatment temperatures (HTTs: 400, 500, 600 °C) via hydrodynamic electrochemical techniques using a rotating disc electrode. EACs and EDCs varied with HTT in accordance with a previous report with a maximal EAC at 500 °C (0.4 mmol(e−).gchar−1) and a large decrease of EDC with HTT. However, while we monitored similar EAC values than in the preceding study, we show that the EDCs have been underestimated by at least 1 order of magnitude, up to 7 mmol(e−).gchar−1 for a HTT of 400 °C. We attribute this existing underestimation to unnoticed slow kinetics of electron transfer from biochars to the dissolved redox mediators used in the monitoring. The EDC of other soil organic constituents such as humic substances may also have been underestimated. These results imply that the redox properties of biochars may have a much bigger impact on soil biogeochemical processes than previously conjectured.

https://biblio.ugent.be/publication/8102691/file/8102694.pdf

Antonin Prévoteau

Papers

Applications of biochar in redox-mediated reactions.

Engineering electrodes for microbial electrocatalysis

Microbial electrosynthesis from CO2: forever a promise?

Integrated Production, Extraction, and Concentration of Acetic Acid from CO2 through Microbial Electrosynthesis

The electron donating capacity of biochar is dramatically underestimated.