Biology-Based Synthesis of Nickel Single Atoms on the Surface of Geobacter sulfurreducens as an Efficient Electrocatalyst for Alkaline Water Electrolysis.

Single-atom metal catalysts are promising electrocatalysts for water electrolysis. Nickel-based electrocatalysts have shown attractive application prospects for water electrolysis. However, synthesizing stable Ni single atoms using chemical and physical approaches remains a practical challenge.

Competition of two highly specialized and efficient acetoclastic electroactive bacteria for acetate in biofilm anode of microbial electrolysis cell.

Maintaining functional stability of microbial electrolysis cell (MEC) treating wastewater depends on maintaining functional redundancy of efficient electroactive bacteria (EAB) on the anode biofilm. Therefore, investigating whether efficient EAB competing for the same resources (electron donor and acceptor) co-exist at the anode biofilm is key for the successful application of MEC for wastewater treatment. Here, we compare the electrochemical and kinetic properties of two efficient acetoclastic EAB, Geobacter sulfurreducens (GS) and Desulfuromonas acetexigens (DA), grown as monoculture in MECs fed with acetate.

Effects of set cathode potentials on microbial electrosynthesis system performance and biocathode methanogen function at a metatranscriptional level.

Microbial electrosynthesis exploits the catalytic activity of microorganisms to utilize a cathode as an electron donor for reducing waste CO to valuable fuels and chemicals. Electromethanogenesis is the process of CO reduction to CH catalyzed by methanogens using the cathode directly as a source of electrons or indirectly via H. Understanding the effects of different set cathode potentials on the functional dynamics of electromethanogenic communities is crucial for the rational design of cathode materials.

Enrichment of salt-tolerant CO-fixing communities in microbial electrosynthesis systems using porous ceramic hollow tube wrapped with carbon cloth as cathode and for CO supply.

Microbial inocula from marine origins are less explored for CO reduction in microbial electrosynthesis (MES) system, although effective CO-fixing communities in marine environments are well-documented. We explored natural saline habitats, mainly salt marsh (SM) and mangrove (M) sediments, as potential inoculum sources for enriching salt-tolerant CO reducing community using two enrichment strategies: H:CO (80:20) enrichment in serum vials and enrichment in cathode chamber of MES reactors operated at -1.0 V vs.

Resistance assessment of microbial electrosynthesis for biochemical production to changes in delivery methods and CO flow rates.

Microbial electrosynthesis (MES) for CO valorization could be influenced by fluctuations in CO mass transfer and flow rates. In this study, we developed an efficient method for CO delivery to cathodic biofilm by directly sparging CO through the pores of ceramic hollow fiber wrapped with Ni-foam/carbon nanotube electrode, and obtained 45% and 77% higher acetate and methane production, respectively. This was followed by the MES stability test in response to fluctuations in CO flow rates varying from 0.

Electroactive biofilms on surface functionalized anodes: The anode respiring behavior of a novel electroactive bacterium, Desulfuromonas acetexigens.

Surface chemistry is known to influence the formation, composition, and electroactivity of electron-conducting biofilms. However, understanding of the evolution of microbial composition during biofilm development and its impact on the electrochemical response is limited. Here we present voltammetric, microscopic and microbial community analysis of biofilms formed under fixed applied potential for modified graphite electrodes during early (90 h) and mature (340 h) growth phases.

Extracellular electron transfer-dependent anaerobic oxidation of ammonium by anammox bacteria.

Anaerobic ammonium oxidation (anammox) bacteria contribute significantly to the global nitrogen cycle and play a major role in sustainable wastewater treatment. Anammox bacteria convert ammonium (NH) to dinitrogen gas (N) using intracellular electron acceptors such as nitrite (NO) or nitric oxide (NO). However, it is still unknown whether anammox bacteria have extracellular electron transfer (EET) capability with transfer of electrons to insoluble extracellular electron acceptors.

Enrichment of sp. and Halophilic Homoacetogens at the Biocathode of Microbial Electrosynthesis System Inoculated With Red Sea Brine Pool.

Homoacetogens are efficient CO fixing bacteria using H as electron donor to produce acetate. These organisms can be enriched at the biocathode of microbial electrosynthesis (MES) for electricity-driven CO reduction to acetate. Studies exploring homoacetogens in MES are mainly conducted using pure or mix-culture anaerobic inocula from samples with standard environmental conditions.

Draft Genome Sequence of sp. Strain 34x, Reconstructed from an Enriched Electromethanogenic Biocathode.

A draft genome sequence of sp. strain 34x was reconstructed from the metagenome of an enriched electromethanogenic biocathode operated in a microbial electrosynthesis (MES) reactor. sp.

Evidence of Spatial Homogeneity in an Electromethanogenic Cathodic Microbial Community.

Microbial electrosynthesis (MES) has been gaining considerable interest as the next step in the evolution of microbial electrochemical technologies. Understanding the niche biocathode environment and microbial community is critical for further developing this technology as the biocathode is key to product formation and efficiency. MES is generally operated to enrich a specific functional group (e.

The role of microbial electrolysis cell in urban wastewater treatment: integration options, challenges, and prospects.

Microbial electrolysis cell (MEC) is an anaerobic biological process for the conversion of organics in wastewater into renewable energy in the form of hydrogen or methane. However, MEC cannot be used as a standalone technology for urban wastewater treatment, and post-treatment or integrated processes are required to meet water reuse and discharge limits. Recent advances in material science and the discovery of new microorganisms capable of extracellular electron transfer to the electrodes have widened the integration opportunities of MEC in mainstream and side-stream urban wastewater treatment.

Dual-Function Electrocatalytic and Macroporous Hollow-Fiber Cathode for Converting Waste Streams to Valuable Resources Using Microbial Electrochemical Systems.

Dual-function electrocatalytic and macroporous hollow-fiber cathodes are recently proposed as promising advanced material for maximizing the conversion of waste streams such as wastewater and waste CO to valuable resources (e.g., clean freshwater, energy, value-added chemicals) in microbial electrochemical systems.

Temporal Microbial Community Dynamics in Microbial Electrolysis Cells - Influence of Acetate and Propionate Concentration.

Microbial electrolysis cells (MECs) are widely considered as a next generation wastewater treatment system. However, fundamental insight on the temporal dynamics of microbial communities associated with MEC performance under different organic types with varied loading concentrations is still unknown, nevertheless this knowledge is essential for optimizing this technology for real-scale applications. Here, the temporal dynamics of anodic microbial communities associated with MEC performance was examined at low (0.

Draft Genome Sequence of Strain 2873, a Novel Anode-Respiring Bacterium.

Here, we report the draft genome sequence of strain 2873, which was originally isolated from digester sludge from a sewage treatment plant in Germany. This bacterium is capable of anode respiration with high electrochemical activity in microbial electrochemical systems. The draft genome contains 3,376 predicted protein-coding genes and putative multiheme c-type cytochromes.

Set anode potentials affect the electron fluxes and microbial community structure in propionate-fed microbial electrolysis cells.

Anode potential has been shown to be a critical factor in the rate of acetate removal in microbial electrolysis cells (MECs), but studies with fermentable substrates and set potentials are lacking. Here, we examined the impact of three different set anode potentials (SAPs; -0.25, 0, and 0.

A Microfiltration Polymer-Based Hollow-Fiber Cathode as a Promising Advanced Material for Simultaneous Recovery of Energy and Water.

A novel electrocatalytic and microfiltration polymeric hollow fiber is fabricated for simultaneous recovery of energy (H ) and clean fresh water from wastewater, hence addressing two grand challenges facing society in the current century (i.e., providing adequate supplies of clean fresh water and energy as the world's population increases).

Multiple paths of electron flow to current in microbial electrolysis cells fed with low and high concentrations of propionate.

Microbial electrolysis cells (MECs) provide a viable approach for bioenergy generation from fermentable substrates such as propionate. However, the paths of electron flow during propionate oxidation in the anode of MECs are unknown. Here, the paths of electron flow involved in propionate oxidation in the anode of two-chambered MECs were examined at low (4.

Graphene-Coated Hollow Fiber Membrane as the Cathode in Anaerobic Electrochemical Membrane Bioreactors--Effect of Configuration and Applied Voltage on Performance and Membrane Fouling.

Electrically conductive, graphene-coated, hollow-fiber porous membranes were used as cathodes in anaerobic electrochemical membrane bioreactors (AnEMBRs) operated at different applied voltages (0.7 and 0.9 V) using a new rectangular reactor configuration compared to a previous tubular design (0.

A novel anaerobic electrochemical membrane bioreactor (AnEMBR) with conductive hollow-fiber membrane for treatment of low-organic strength solutions.

A new anaerobic treatment system that combined a microbial electrolysis cell (MEC) with membrane filtration using electrically conductive, porous, nickel-based hollow-fiber membranes (Ni-HFMs) was developed to treat low organic strength solution and recover energy in the form of biogas. This new system is called an anaerobic electrochemical membrane bioreactor (AnEMBR). The Ni-HFM served the dual function as the cathode for hydrogen evolution reaction (HER) and the membrane for filtration of the effluent.

A hybrid microbial fuel cell membrane bioreactor with a conductive ultrafiltration membrane biocathode for wastewater treatment.

A new hybrid, air-biocathode microbial fuel cell-membrane bioreactor (MFC-MBR) system was developed to achieve simultaneous wastewater treatment and ultrafiltration to produce water for direct reclamation. The combined advantages of this system were achieved by using an electrically conductive ultrafiltration membrane as both the cathode and the membrane for wastewater filtration. The MFC-MBR used an air-biocathode, and it was shown to have good performance relative to an otherwise identical cathode containing a platinum catalyst.

Charge transport through Geobacter sulfurreducens biofilms grown on graphite rods.

Biofilms of the electroactive bacterium Geobacter sulfurreducens were induced to grow on graphite-rod electrodes under a potential of 0 V (vs Ag/AgCl) in the presence of acetate as an electron donor. Increased anodic currents for bioelectrocatalytic oxidation of acetate were obtained when the electrodes were incubated for longer periods with periodic electron-donor feeding. The maximum current density for acetate oxidation increased 2.

Microbial analysis of anodic biofilm in a microbial fuel cell using slaughterhouse wastewater.

The ability of dual-chambered microbial fuel cell, fed with slaughterhouse wastewater with an anaerobic mixed-sludge as initial source of bacteria, to generate power is investigated. MFC voltage generation across a fixed 100 Ω load indicates power generation capability, with power production correlated to changes in anolyte VFA content. A maximum MFC power density of 578 mW/m(2) is obtained for an MFC developed under 100 Ω load, compared to a maximum power density of 277 mW/m(2) for an MFC developed under higher resistance (1 MΩ) control conditions.

On the dynamic response of the anode in microbial fuel cells.

A study of the dynamic response of a microbial fuel cell (MFC) using membrane electrode assemblies (MEAs) designed for air breathing cathode operation is reported. The MFC used four MEAs simultaneously and has a low internal resistance. An increased concentration of glucose produced a non-linear increase in the maximum current reached.

Evaluation of hydrolysis and fermentation rates in microbial fuel cells.

This study determined the influence of substrate degradation on power generation in microbial fuel cells (MFCs) and microbial community selection on the anode. Air cathode MFCs were fed synthetic medium containing different substrates (acetate, glucose and starch) using primary clarifier sewage as source of electroactive bacteria. The complexity of the substrate affected the MFC performance both for power generation and COD removal.