S. Venkata Ramana, Cristina M. Cordas, Sara C. Matias et al.

Research Square • 2020

Abstract In the present work the electrochemical behaviour of microbial cells from a biocathode microbial fuel cell (MFC) functioning with wastewater was evaluated by cyclic voltammetry. In-situ electrochemical assays were performed and, under the tested experimental conditions, the biocathode medium was found to be the most efficient for the cathodic catalysed electrochemical reduction of oxygen. Different controls using sterile media and membranes covering the electrodes were performed and compared with the regular biocathode results. In the biocathode chamber, the presence of bacteria was associated with the enhanced active redox processes and with the higher electrochemical reduction of oxygen activity. The present study is a contribution to the understanding of the viability and advantages of the biocathodes use in MFC.

Maria Essa, Saima Mehar, Haneef Ur Rehman

Research Square • 2024

Abstract Microbial fuel cell (MFC) technology offers an innovative and sustainable solution for energy production, particularly in electricity-deprived regions. This study focuses on the design of a microbial biofuel cell that utilizes S. cerevisiae to generate bioelectricity from fisheries wastewate through bio-elecrochemical reaction. The MFC system harnesses electrons released during biochemical reactions catalyzed by microorganisms. Optimization of physical parameters was performed to maximize bioelectricity generation from fisheries wastewater. The results revealed that S. cerevisiae -based MFC achieved the highest bioelectricity production at 35 ºC, pH 8, and an incubation period of 72 hours. To enhance performance, a flow rate of 50 mL/min of oxygen in the wastewater was found to be the most effective for bioelectricity generation. The findings demonstrate the practicality and sustainability of the S. cerevisiae-based MFC as a viable technique for both bioelectricity production and wastewater management in the fisheries industry. This innovative approach not only addresses the basic electricity needs of electricity-deprived regions but also helps mitigate wastewater pollution, presenting an environmentally friendly solution. The study highlights the potential of MFC technology to contribute to renewable energy generation and environmental sustainability in regions reliant on fisheries wastewater.

Basem S. Zakaria, Bipro Ranjan Dhar

bioRxiv (Cold Spring Harbor Laboratory) • 2020

Abstract The microbial electrolysis cell assisted anaerobic digestion (MEC-AD) holds great promises over conventional anaerobic digestion. This article reports an experimental investigation of extracellular polymeric substances (EPS), reactive oxygen species (ROS), and the expression of genes associated with extracellular electron transfer (EET) in methanogenic biocathodes. The MEC-AD systems were examined using two cathode materials: carbon fibers and stainless-steel mesh. A higher abundance of hydrogenotrophic Methanobacterium sp. and homoacetogenic Acetobacterium sp. appeared to play a major role in superior methanogenesis from stainless steel biocathode than carbon fibers. Moreover, the higher secretion of EPS accompanied by the lower ROS level in stainless steel biocathode indicated that higher EPS perhaps protected cells from harsh metabolic conditions (possibly unfavorable local pH) induced by faster catalysis of hydrogen evolution reaction. In contrast, EET-associated gene expression patterns were comparable in both biocathodes. Thus, these results indicated hydrogenotrophic methanogenesis is the key mechanism, while cathodic EET has a trivial role in distinguishing performances between two cathode electrodes. These results provide new insights into the efficient methanogenic biocathode development.

Pei Zhang

ECS Meeting Abstracts • 2017

A novel microorganism of Bioechem proprietary, named P1, promotes high electron transport activity on cathode, shown as the highest cathodic current output than the other reported microorganisms. A biocathode, using P1 as catalyst, was tested in an electrochemical system and showed enhanced performance than abiotic cathode. The performance of the biocathode was further improved through the microbial-electrode surface modification by reducing total free energy of the system for better sorption of the bacteria cells on to the electrode; providing more bacteria sorption sites on surface of the electrode; And adjusting the dissolved oxygen concentration on bacteria-electrode interface for faster bacteria metabolic rate and electron transfer rate. With the enhanced properties of the biocathode, the microorganisms can promote the on site energy supply 10 times or more. The biocathode was also first time applied into a primary battery setup and showed promising capacity and durability compare to a same size battery setup using abiotic electrodes and traditional chemical electrolyte.

Szymon Buchaniec, M. Gnatowski, H. Hasegawa et al.

Energies • 2023

Solid oxide fuel cells are becoming increasingly important in various applications, from households to large-scale power plants. However, these electrochemical energy conversion devices have complex behavior that is difficult to understand and optimize. A numerical simulation is a primary tool for analysis and optimization-design. One of the most significant challenges in this field is improving microscale transport phenomena and electrode reaction models. Two main categories of simulation are black-box and white-box models. The former requires large experimental datasets and lacks physical constraints, while the latter inherits the inaccuracy of typical electrochemical reaction models. Here we show a micro-scale artificial neural network-supported numerical simulation that allows for overcoming those issues. In our research, we substituted one equation in the system, an electrochemical model, with an artificial neural network prediction. The data-driven prediction is constrained and must satisfy all reminded balance equations in the system. The results show that the proposed model can simulate an anode-electrode’s thermodynamic losses with improved accuracy compared with the classical approach. The coefficient of determination R2 for the proposed model was equal to 0.8810 for 800 °C, 0.8720 for 900 °C, and 0.8436 for 1000 °C. The findings open a way for improving the accuracy and computational complexity of electrochemical models in solid oxide fuel cell simulations.

Timothy T. Yang, W. Saidi

The Journal of Physical Chemistry Letters • 2022

The volcano trend has been widely utilized to forecast new optimum catalysts in computational chemistry while the Butler-Volmer relationship is the norm to explain current-potential characteristics from cyclic voltammetry in analytical chemistry. Herein, we develop an electrochemical model for hydrogen evolution reaction exchange currents that reconciles device-level chemistry, atomic-level volcano trend, and the Butler-Volmer relation. We show that the model is a function of the easy-to-compute hydrogen adsorption energy invariably obtained from first-principles atomic simulations. In addition, the model reproduces with high fidelity the experimental exchange currents for elemental metal catalysts over 15 orders of magnitude and is consistent with the recently proposed analytical model based on a data-driven approach. Our findings based on fundamental electrochemistry principles are general and can be applied to other reactions including CO2 reduction, metal oxidation, and lithium (de)intercalation reactions.

T. Yamahigashi, J. Shimura, K. Shibuya et al.

2023 11th International Conference on Power Electronics and ECCE Asia (ICPE 2023 - ECCE Asia) • 2023

An equivalent circuit model of lithium-ion batteries which has a nonlinear resistor governed by Butler-Volmer’s equation and a constant phase element was investigated. The current dependence of the real battery could be reproduced well by the contribution of the nonlinear resistor, and the transient response of voltage could be reproduced well by the contribution of the constant phase element.

Clifford M. Krowne

International Journal of Quantum Chemistry • 2023

The vanadium redox flow battery has been intensively examined since the 1970s. What is missing is a connection between the current‐overpotential Butler‐Volmer equation, which provides an extremely helpful starting point for analytical and numerical studies, and microscopic quantum mechanical behavior at the atomic level. Such a connection will allow further advancements beyond the macroscopic, though very useful and insightful, modeling already done in the literature. Here we show rigorously the connection between the Butler‐Volmer transfer coefficients, and the Marcus Gibbs free energy quantum mechanical parameters, and develop the equation directly in terms of the quantum mechanical parameters.

Robert Morasch, H. Gasteiger, Bharatkumar Suthar

Journal of The Electrochemical Society • 2023

The expression for the exchange current density to describe the intercalation kinetics of Li-ion battery materials proposed by Newman and coworkers has been used extensively for battery modeling, however its applicability to existing battery materials should be validated. Here we show an electrochemical impedance spectroscopy (EIS) analysis of the kinetic behavior of NCM 111 as a function of electrolyte salt concentration and state-of-charge (SOC) and compare it to the proposed theory. An areal capacity dependent EIS analysis first gives insights into the feasibility of measuring kinetic and transport parameters, including the solid diffusion resistance of lithium, showing that low-areal capacity electrodes are required to predominantly probe the kinetics. We then show how the charge transfer kinetics follow a Butler-Volmer type concentration dependent behavior for lower concentrated electrolytes (≤1.5 M) but deviate from the proposed theory at higher salt concentrations. A further SOC dependent analysis shows how NCM 111 generally follows the proposed theory of U-shaped symmetric kinetics, but the limited oxidative stability window leads to practically asymmetric kinetics for charging and discharging. This asymmetry is visible in NCM 111 lithiation and delithiation rate tests, where upon lithiation the kinetics generally become slower for higher degrees of lithiation, limiting the performance.

B. Paneru, Biplov Paneru, Nitish Pandey et al.

International Journal of Informatics, Information System and Computer Engineering (INJIISCOM) • 2024

For the analysis of  Proton Exchange Membrane Fuel Cell (PEMFC’s) efficiency, the Nernst equation and Butler-Volmer's concepts were used. The mathematical models using both equations were developed in MATLAB and compiled. The results generated by the output current based on the input parameters of the experimental data were compared with the experimental results for the two modelled PEMFCs. The parameters temperature, pressure, hydrogen concentration, and oxygen concentration at different values of external resistance were used to determine the change in output current in both models built in MATLAB. This sensitivity analysis generated negative output current values and highly dissimilar values with the experimental results for the same input parameters for both models due to the less use of input parameters in the model. The results showed that the PEMFC's performance is affected by most parameters, and many influencing parameters must be used to develop a perfect mathematical model of the PEMFC.        

D. N. Buckley, Johna Leddy

Journal of The Electrochemical Society • 2024

We revisit the classical derivation of the Butler-Volmer equation to include the effect of the electrode metal. If the metal is replaced by one with a different work function, keeping other conditions in the electrode constant, the chemical potential of electrons μ_e and the Galvani potential φ change in a complementary manner. Changes in μ_e and φ each impact the free energies of activation of the forward and backward electron transfer reactions, so we modify the classical expressions which relate them to applied voltage E by including also the effect of μ_e. Inserting these expressions in an Eyring-Polyani or Arrhenius type equation in the traditional way, we obtain a modified Butler-Volmer equation which expresses current density as a function of both E and Δμ_e. The exchange current density j_0 appears as an exponential function of Δμ_e. For the work function Φ of the metal, the approximation Δμ_e≈-FΔΦ yields a linear relationship between ln⁡〖j_0 〗 and Φ. The linear increase in ln⁡〖j_0 〗 with Φ has long been reported. We show two experimental examples: the aqueous Fe2+/Fe3+ couple with positive slope and the hydrogen evolution reaction (HER) with parallel lines for the d and sp metals, both with positive slopes.

N. Stein, H. Hamelers, G. van Straten et al.

Biosensors • 2012

Polarization curves are of paramount importance for the detection of toxic components in microbial fuel cell (MFC) based biosensors. In this study, polarization curves were made under non-toxic conditions and under toxic conditions after the addition of various concentrations of nickel, bentazon, sodiumdodecyl sulfate and potassium ferricyanide. The experimental polarization curves show that toxic components have an effect on the electrochemically active bacteria in the cell. (Extended) Butler Volmer Monod (BVM) models were used to describe the polarization curves of the MFC under nontoxic and toxic conditions. It was possible to properly fit the (extended) BVM models using linear regression techniques to the polarization curves and to distinguish between different types of kinetic inhibitions. For each of the toxic components, the value of the kinetic inhibition constant Ki was also estimated from the experimental data. The value of Ki indicates the sensitivity of the sensor for a specific component and thus can be used for the selection of the biosensor for a toxic component.

L. Zhao, J. Brouwer, J. Naviaux et al.

ASME 2014 12th International Conference on Fuel Cell Science, Engineering and Technology • 2014

Microbial fuel cells (MFCs) are promising for simultaneous treatment of wastewater and energy production. In this study, a mathematical model for microbial fuel cells with air cathodes was developed and demonstrated by integrating biochemical reactions, Butler-Volmer expressions and mass/charge balances. The model developed is focused on describing and understanding the steady-state polarization curves of the microbial fuel cells with various levels and methods of anode-biofilm growth with air cathodes. This polarization model combines enzyme kinetics and electrochemical kinetics, and is able to describe measured polarization curves for microbial fuel cells with different anode-biofilm growth. The MFC model developed has been verified with the experimental data collected. The simulation results provide insights into the limiting physical, chemical and electrochemical phenomena and their effects on cell performance. For example, the current MFC data demonstrated performance primarily limited by cathode electrochemical kinetics.

Ahmed Y. Radeef, Z. Ismail

International Journal of Green Energy • 2021

ABSTRACT Potato chips processing industry generally discharge large volumes of organic loaded-wastewater and significant amounts of peels as solid wastes. In this study, a dual chamber microbial fuel cell (MFC) was setup, and continuously operated for 120 days for combined biotreatment of potato chips processing wastewater (PCW) and waste potato peels (PP) associated with electricity generation. The discarded PP were dried, grinded, and added to the PCW as a powder at concentrations of 0, 2.5, and 5 g PP/L resulted in three different organic loadings, denoted as OL0, OL1, and OL2, respectively. The results demonstrated significant removal efficiency of COD up to 99% with maximum power generation of 612.5, 800, and 1012.5 mW/m3 for OL0, OL1, and OL2, respectively. Butler–Volmer–Monod model was proposed to describe the overpotential-polarization curve for the MFC. Significant agreement was observed between the predicated and experimental results with determination coefficient (R2) values > 0.91.

T. Kamperidis, A. Tremouli, Antonis Peppas et al.

Energies • 2022

Bioelectrochemical systems have been the focus of extensive research due to their unique advantages of converting the chemical energy stored in waste to electricity. To acquire a better understanding and optimize these systems, modelling has been employed. A 2D microbial fuel cell (MFC) model was developed using the finite element software Comsol Multiphysics® (version 5.2), simulating a two-chamber MFC operating in batch mode. By solving mass and charge balance equations along with Monod–Butler–Volmer kinetics, the operation of the MFC was simulated. The model accurately describes voltage output and substrate consumption in the MFC. The computational results were compared with experimental data, thus validating the model. The voltage output and substrate consumption originating from the model were in agreement with the experimental data for two different cases (100 Ω, 1000 Ω external resistances). A polarization curve was extracted from the model by shifting the external resistance gradually, calculating a similar maximum power (47 mW/m2) to the observed experimental one (49 mW/m2). The validated model was used to predict the MFC response to varying initial substrate concentrations (0.125–4 g COD/L) and electrolyte conductivity (0.04–100 S/m) in order to determine the optimum operating conditions.

Stephen D. Springer, Alison Butler

ChemInform • 2016

Abstract Review: 99 refs.

Moriah Sandy, Alison Butler

ChemInform • 2010

Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Orpheus Butler, Stefano Manzoni, Charles Warren

• 2025

Intracellular storage of carbon (C) by soil micro-organisms is emerging as a key process that influences soil biogeochemical cycling and the broader function of terrestrial ecosystems. One likely role of intracellular C storage is to serve as a stoichiometric buffer against nutritional imbalances in the microbial substrate. Such a function would make storage compounds vital to the long-term function of ecosystems associated with strongly weathered, low fertility soils, yet there have been few studies of intracellular carbon storage in such ecosystems. We examined the dynamics of two putative storage compounds (triacylglycerol [TAG] and polyhydroxybutyrate [PHB]) across two natural soil fertility gradients in eastern Australia. Across all sites and samples, absolute quantities of storage compounds ranged from 0 to 173 µg C g soil-1 in the case of TAG and 0 to 56 µg C g soil-1 for PHB. When standardized to total soil organic C, quantities of storage compounds tended to be markedly higher than those observed in prior studies of temperate and/or agricultural soils. Allocation to storage compounds followed strong trends across natural gradients of soil fertility and tended to peak in phosphorus-deficient and/or retrogressive ecosystems. Across soils of differing parent material, allocation to C storage was highest in infertile soils derived from phosphorus-depleted sandstone and ironstone compared to soils derived from shale and basalt. Likewise, allocation to C storage increased throughout ~700k years of soil development across a strongly weathered podzolic dune chronosequence. Dynamics of community-level C storage allocation were evidently underpinned by a combination of assemblage-level processes, most notably changes in the relative abundance of TAG-rich, C-limited fungal taxa, and physiological plasticity on the level of individual P-limited bacterial cells. Our findings are largely consistent with the surplus/reserve storage framework and highlight the importance of storage compounds for the function of oligotrophic ecosystems and as a major pool of C in soil.

Pam Engelberts, Jun Ye, Donovan Parks et al.

Research Square • 2024

Abstract Fluorescence in situ hybridisation (FISH) is a powerful tool for visualising the spatial organisation of microbial communities. However, traditional FISH has several limitations, including ​​limited phylogenetic resolution, difficulty visualising certain lineages​,​ ​​and the​​ design and optimis​ation of​ new probes is time consuming and does not scale​ to the ​known​ diversity of microbial life. Here, we present GenomeFISH, a high-throughput, genome-based FISH approach that can differentiate strains within complex communities. Fluorescent probes are generated from the genomes of single cells, which are ​obtained ​from environmental or clinical samples through fluorescence activated single-cell sorting (FACS). GenomeFISH can ​distinguish between ​strains with up to 99% average nucleotide identity and was successfully applied to visualise strains in mock communities and human faecal samples. Given the superior sensitivity and specificity of GenomeFISH, we envisage it will become the gold standard in the visualisation of complex microbial systems.

Stacey Butler, James O’Dwyer

bioRxiv (Cold Spring Harbor Laboratory) • 2018

Abstract Competition and mutualism are inevitable processes in microbial ecology, and a central question is which and how many taxa will persist in the face of these interactions. Ecological theory has demonstrated that when direct, pairwise interactions among a group of species are too numerous, or too strong, then the coexistence of these species will be unstable to any slight perturbation. This instability worsens when mutualistic interactions complement competition. Here, we refine and to some extent overturn that understanding, by considering explicitly the resources that microbes consume and produce. In contrast to more complex organisms, microbial cells consume primarily abiotic resources, and mutualistic interactions are often mediated by these same abiotic resources through the mechanism of cross-feeding. Our model therefore considers the consumption and production of a set of abiotic resources by a group of microbial species. We show that if microbes consume, but do not produce resources, then any positive equilibrium will always be stable to small perturbations. We go on to show that in the presence of crossfeeding, stability is no longer guaranteed. However, stability still holds when mutualistic interations are either symmetric, or sufficiently weak.

Stacey Butler, James P. O’Dwyer

Nature Communications • 2018

Abstract Competition and mutualism are inevitable processes in microbial ecology, and a central question is which and how many taxa will persist in the face of these interactions. Ecological theory has demonstrated that when direct, pairwise interactions among a group of species are too numerous, or too strong, then the coexistence of these species will be unstable to any slight perturbation. Here, we refine and to some extent overturn that understanding, by considering explicitly the resources that microbes consume and produce. In contrast to more complex organisms, microbial cells consume primarily abiotic resources, and mutualistic interactions are often mediated through the mechanism of crossfeeding. We show that if microbes consume, but do not produce resources, then any positive equilibrium will always be stable to small perturbations. We go on to show that in the presence of crossfeeding, stability is no longer guaranteed. However, positive equilibria remain stable whenever mutualistic interactions are either sufficiently weak, or when all pairs of taxa reciprocate each other’s assistance.

T. Chung, B. Dhar

Frontiers in Energy Research • 2021

For the past two decades, many successful applications of microbial electrochemical technologies (METs), such as bioenergy generation, environmental monitoring, resource recovery, and platform chemicals production, have been demonstrated. Despite these tremendous potentials, the scaling-up and commercialization of METs are still quite challenging. Depending on target applications, common challenges may include expensive and tedious fabrication processes, prolonged start-up times, complex design requirements and their scalability for large-scale systems. Incorporating the three-dimensional printing (3DP) technologies have recently emerged as an effective and highly promising method for fabricating METs to demonstrate power generation and biosensing at the bench scale. Notably, low-cost and rapid fabrication of complex and miniaturized designs of METs was achieved, which is not feasible using the traditional methods. Utilizing 3DP showed tremendous potentials to aid the optimization of functional large-scale METs, which are essential for scaling-up purposes. Moreover, 3D-printed bioanode could provide rapid start-up in the current generation from METs without any time lags. Despite numerous review articles published on different scientific and applied aspects of METs, as per the authors’ knowledge, no published review articles explicitly highlighted the applicability and potential of 3DP for developing METs. Hence, this review targets to provide a current overview and status of 3DP applications for advancing METs and their future outlook.

A. Karbelkar, E. Reynolds, Rachel Ahlmark et al.

ACS Central Science • 2021

Organophosphate (OP) pesticides cause hundreds of illnesses and deaths annually. Unfortunately, exposures are often detected by monitoring degradation products in blood and urine, with few effective methods for detection and remediation at the point of dispersal. We have developed an innovative strategy to remediate these compounds: an engineered microbial technology for the targeted detection and destruction of OP pesticides. This system is based upon microbial electrochemistry using two engineered strains. The strains are combined such that the first microbe (E. coli) degrades the pesticide, while the second (S. oneidensis) generates current in response to the degradation product without requiring external electrochemical stimulus or labels. This cellular technology is unique in that the E. coli serves only as an inert scaffold for enzymes to degrade OPs, circumventing a fundamental requirement of coculture design: maintaining the viability of two microbial strains simultaneously. With this platform, we can detect OP degradation products at submicromolar levels, outperforming reported colorimetric and fluorescence sensors. Importantly, this approach affords a modular, adaptable strategy that can be expanded to additional environmental contaminants.

M. de la Fuente, Carlos Gallardo-Bustos, R. De la Iglesia et al.

International Journal of Environmental Research and Public Health • 2022

For many years, the world’s coastal marine ecosystems have received industrial waste with high nitrogen concentrations, generating the eutrophication of these ecosystems. Different physicochemical-biological technologies have been developed to remove the nitrogen present in wastewater. However, conventional technologies have high operating costs and excessive production of brines or sludge which compromise the sustainability of the treatment. Microbial electrochemical technologies (METs) have begun to gain attention due to their cost-efficiency in removing nitrogen and organic matter using the metabolic capacity of microorganisms. This article combines a critical review of the environmental problems associated with the discharge of the excess nitrogen and the biological processes involved in its biogeochemical cycle; with a comparative analysis of conventional treatment technologies and METs especially designed for nitrogen removal. Finally, current METs limitations and perspectives as a sustainable nitrogen treatment alternative and efficient microbial enrichment techniques are included.

Anusha Ganta, Yasser Bashir, Sovik Das

Energies • 2022

A milk-processing plant was drafted as a distinctive staple industry amid the diverse field of industries. Dairy products such as yogurt, cheese, milk powder, etc., consume a huge amount of water not only for product processing, but also for sanitary purposes and for washing dairy-based industrial gear. Henceforth, the wastewater released after the above-mentioned operations comprises a greater concentration of nutrients, chemical oxygen demand, biochemical oxygen demand, total suspended solids, and organic and inorganic contents that can pose severe ecological issues if not managed effectively. The well-known processes such as coagulation–flocculation, membrane technologies, electrocoagulation, and other biological processes such as use of a sequencing batch reactor, upflow sludge anaerobic blanket reactor, etc., that are exploited for the treatment of dairy effluent are extremely energy-exhaustive and acquire huge costs in terms of fabrication and maintenance. In addition, these processes are not competent in totally removing various contaminants that exist in dairy effluent. Accordingly, to decrease the energy need, microbial electrochemical technologies (METs) can be effectively employed, thereby also compensating the purification charges by converting the chemical energy present in impurities into bioelectricity and value-added products. Based on this, the current review article illuminates the application of diverse METs as a suitable substitute for traditional technology for treating dairy wastewater. Additionally, several hindrances on the way to real-world application and techno-economic assessment of revolutionary METs are also deliberated.

B. S. Zakaria, B. Dhar

Processes • 2022

: The growing concern about residual antibiotics in the water environment pushes for innovative and cost-effective technologies for antibiotics removal from wastewater. In this context, various microbial electrochemical systems have been investigated as an alternative to conventional wastewater technologies that are usually ineffective for the adequate removal of antibiotics. This review article details the development of stand-alone and hybrid or integrated microbial electrochemical systems for antibiotics removal from wastewater. First, technical features, antibiotics removal efficiencies, process optimization, and technological bottlenecks of these systems are discussed. Sec-ond, a comparative summary based on the existing reports was established to provide insights into the selection between stand-alone and hybrid systems. Finally, research gaps, the relevance of recent progress in complementary areas, and future research needs have been discussed.

S. N. Hosseini, P. S. Das, Vahid Khojasteh Lazarjan et al.

IEEE Transactions on Biomedical Circuits and Systems • 2023

Rapid, high-sensitivity, and real-time characterization of microorganisms plays a significant role in several areas, including clinical diagnosis, human healthcare, early detection of outbreaks, and the protection of living beings. Integrating microbiology and electrical engineering promises the development of low-cost, miniaturized, autonomous, and high-sensitivity sensors to quantify and characterize bacterial strains at various concentrations. Electrochemical-based biosensors are receiving particular attention in microbiological applications among the different biosensing devices. Several approaches have been adopted to design and fabricate cutting-edge, miniaturized, and portable electrochemical biosensors to track and monitor bacterial cultures in real time. These techniques differ in their sensing interface circuits and microelectrode fabrication. The goals of this review are (1) to summarize the current state of CMOS sensing circuit designs in label-free electrochemical biosensors for bacteria monitoring and (2) to discuss the material and size of the electrodes used in electrochemical biosensors in microbiological applications. In this paper, we reviewed the latest and most advanced CMOS integrated interface circuits that have recently been used in electrochemical biosensors to identify and characterize bacteria species, such as impedance spectroscopy, capacitive, amperometry, and voltammetry, etc. In addition to the interface circuit design, other crucial factors, such as the material and scale of the electrodes, must be considered to increase the sensitivity of electrochemical biosensors. Surveying the literature in this field improves our knowledge about the impact of electrode designs and materials on sensing precision and will help future designers adapt, design, and fabricate appropriate electrode configurations based on their application. Thus, we summarized the conventional microelectrode designs and materials mainly employed in microbial sensors, including interdigitated electrodes (IDEs), microelectrode arrays (MEAs), paper, and carbon-based electrodes, etc.

Ruixiang Li, Jinning Wang, Tian Li et al.

Critical Reviews in Environmental Science and Technology • 2022

Abstract Remediation of contaminated soil and sediments has been drawing our attention, efficient and eco-friendly technologies are urgently needed for the removal of pollutants in soil and sediments. Although conventional remediation technologies have been in application for decades and have achieved great performance, the significant drawbacks limit their application (e.g., complicated operation and secondary pollution). Microbial electrochemical system (MES) has been intensively studied as a promising technology for soil/sediment remediation. Compared with other technologies, soil/sediment MES (SMES) exhibited many potential benefits, such as adequate electron acceptors, self-sustained operation, and facile control. However, due to the diversity of soil/sediment contamination and the significant difference in the remediation performance of conventional SMES, it is imperative to develop strategies for enhancing the remediation performance of SMES. In this review, we briefly introduce the removal mechanisms of different pollutants, including the mechanisms of electron releasing, transportation, and receiving. Afterward, we comprehensively present a detailed discussion of the recent progress in the enhancement of soil/sediment remediation in terms of reactor configurations, electrode arrangements, and electrode materials. Moreover, different materials used to amend soil/sediments and their corresponding enhancement principles are summarized in detail. Finally, we discuss the current emerging limitations of SMES and the future research endeavors to improve the performance and promote the practical application. Therefore, this review can fill the gaps in SMES development and guide the practical application in contaminated soil/sediments. Graphical abstract

Kevin Beaver, Ashwini Dantanarayana, Ana Clara Bonizol Zani et al.

Journal of The Electrochemical Society • 2023

With applications in bioremediation, biosensing, and bioenergy, microbial electrochemical systems are a rapidly growing, multidisciplinary field within biological, chemical, and materials science. Since these systems use living microorganisms as biocatalysts, it is important to understand how microbial physiology, specifically biofilm formation, affects these electrochemical systems. Specifically, the literature lacks research that assesses the effects of biofilm on metabolic current output in mediated electron transfer systems. In this study, Rhodobacter capsulatus and Pseudomonas putida GPo1 were used as model, nonpathogenic strains that facilitate electron transfer via diffusible redox mediators. Nitric oxide has gained attention in biomedicine as a gaseous signaling molecule, which at sublethal concentrations may either augment or inhibit biofilm formation depending on the bacterial species. In R. capsulatus, nitric oxide treatment was associated with increased current yield and improved biofilm formation. However, in P. putida-GPo1, nitric oxide treatment corresponded to significantly reduced current output, as well as biofilm dispersal. In addition to highlighting the use of electrochemical tools to assess the effects of nitric oxide in biofilm formation, these findings demonstrate that biofilm-based mediated electron transfer systems benefit from the increased electrochemical output and enhanced cell adhesion, which is promising for more robust applications compared to their planktonic counterpart

Wenduo Lu, Yuening Song, Chuanqi Liu et al.

Fermentation • 2023

Microbial electrochemical CO2 reduction and in-situ biogas upgrading can effectively reduce the CO2 content in biogas produced during anaerobic digestion, thereby reducing CO2 emissions and achieving carbon reduction. pH is an important indicator in this process as it can significantly change the solubility and forms of CO2 in the aquatic phase. This study comprehensively evaluated the optimal pH value from the perspectives of methane upgrading performance and electron utilization efficiency and observed and analyzed the morphology of the biofilm on the electrode surface and the microbial community in the cathodic region under optimal conditions. The results showed that the optimal pH was 6.5; methane content reached ~88.3% in the biogas; methane production reached a maximum of 22.1 ± 0.1 mmol·d−1, with an increase in methane production compared to the control group reaching a maximum of 1.7 mmol·d−1; and CO2 conversion rate reached ~22.9%. A dense biofilm with a thickness of 51.3 μm formed on the electrode surface, with Methanobacterium being the dominant genus, with a high relative abundance of 69.3%, and Geobacter had a relative abundance of 20.1%. The above findings have important guiding significance for the practical application of methane upgrading.

Zeena Wang, Dunzhu Li, Yunhong Shi et al.

Sensors • 2023

Hydrogel materials have been used extensively in microbial electrochemical technology (MET) and sensor development due to their high biocompatibility and low toxicity. With an increasing demand for sensors across different sectors, it is crucial to understand the current state within the sectors of hydrogel METs and sensors. Surprisingly, a systematic review examining the application of hydrogel-based METs to sensor technologies has not yet been conducted. This review aimed to identify the current research progress surrounding the incorporation of hydrogels within METs and sensors development, with a specific focus on microbial fuel cells (MFCs) and microbial electrolysis cells (MECs). The manufacturing process/cost, operational performance, analysis accuracy and stability of typical hydrogel materials in METs and sensors were summarised and analysed. The current challenges facing the technology as well as potential direction for future research were also discussed. This review will substantially promote the understanding of hydrogel materials used in METs and benefit the development of electrochemical biosensors using hydrogel-based METs.

E. Klein, Melanie T. Knoll, J. Gescher

Microbial Biotechnology • 2023

Microbial electrochemical systems (MESs) are a highly versatile platform technology with a particular focus on power or energy production. Often, they are used in combination with substrate conversion (e.g., wastewater treatment) and production of value‐added compounds via electrode‐assisted fermentation. This rapidly evolving field has seen great improvements both technically and biologically, but this interdisciplinarity sometimes hampers overseeing strategies to increase process efficiency. In this review, we first briefly summarize the terminology of the technology and outline the biological background that is essential for understanding and thus improving MES technology. Thereafter, recent research on improvements at the biofilm–electrode interface will be summarized and discussed, distinguishing between biotic and abiotic approaches. The two approaches are then compared, and resulting future directions are discussed. This mini‐review therefore provides basic knowledge of MES technology and the underlying microbiology in general and reviews recent improvements at the bacteria–electrode interface.

Jie Cheng, Meng Liu, Xin Su et al.

Environmental Science & Technology • 2023

Adding conductive materials to the cathode of a microbial electrochemical system (MES) can alter the route of interspecies electron transfer and the kinetics of reduction reactions. We tested reductive dechlorination of γ-hexachlorocyclohexane (γ-HCH), along with CH4 production, in MES systems whose cathodes were coated with conductive magnetite nanoparticles (NaFe), biochar (BC), magnetic biochar (FeBC), or anti-conductive silica biochar (SiBC). Coating with NaFe enriched electroactive microorganisms, boosted electro-bioreduction, and accelerated γ-HCH dechlorination and CH4 production. In contrast, BC only accelerated dechlorination, while FeBC only accelerated methanogenesis, because of their assemblies of functional taxa that selectively transferred electrons to those electron sinks. SiBC, which decreased electro-bioreduction, yielded the highest CH4 production and increased methanogens and the mcrA gene. This study provides a strategy to selectively control the distribution of electrons between reductive dechlorination and methanogenesis by adding conductive or anti-conductive materials to the MES's cathode. If the goal is to maximize dechlorination and minimize methane generation, then BC is the optimal conductive material. If the goal is to accelerate electro-bioreduction, then the best addition is NaFe. If the goal is to increase the rate of methanogenesis, adding anti-conductive SiBC is the best.

Kartik Aiyer, Lucinda Elizabeth Doyle

Electrochemistry • 2023

Developed as the earliest application of electroactive microorganisms, microbial fuel cells (MFCs) have been intensively researched over the past two decades. The original goal of harnessing microbially-derived electricity for power generation has been partially successful, particularly for low-wattage devices. Beyond this, MFC technology has proven versatile with additional applications including as a research tool for the enrichment and isolation of novel electroactive microorganisms, as early-detection biosensors, for wastewater treatment and (with supply of additional energy) for microbial electrosynthesis. This chapter provides a comprehensive landscape of modern MFC technology. A brief historical perspective is followed by a primer of MFCs for the beginner. Next, a detailed discussed of the current knowledge on microbial electroactivity, best practices for characterisation, and practicalities of MFC operation is presented. The chapter concludes with an examination of present and emerging MFC applications.

Dan-Dan Zhai, Yang-Chun Yong

Chemical Biotechnology and Bioengineering • 2015

Microbial electrochemical systems (MES) are a relatively new electrochemistry research field and hold great potential for various applications by taking advantage of the metabolic diversity of microorganisms and the flexibility of electrochemical techniques. During the past few decades, a large variety of interesting and novel applications such as energy-generating wastewater treatment, bioelectrochemical CO2 fixation and transformation, bioelectrochemical hydrogen synthesis, desalination, and waste heating energy harvesting have been demonstrated. Meanwhile, multidisciplinary research to improve the performance/efficiency of MES is attracting widespread interest. In the light of deeper understanding of MES through chemistry and biology studies, new interdisciplinary chemical biotechnology research taking advantage of both disciplines is emerging and becoming a hot research topic in this area. In this chapter, the great contributions of chemical bioengineering to MES are highlighted. In particular, augmentation of extracellular electron transfer between bacteria and the electrode by chemicals, conductive polymers, and carbon nanomaterials are reviewed. Moreover, other chemical bioengineering approaches to improve MES through manipulation of cell physiology, such as by surfactant and metal ion treatment, quorum sensing signaling modulation, and cell immobilization, are also emphasized. Future directions for chemical bioengineering of MES are also discussed.

Carlos A. Ramírez-Vargas, Amanda Prado, Carlos A. Arias et al.

Preprints.org • 2018

Microbial electrochemical technologies (MET) rely on the presence of the metabolic activity of electroactive bacteria for the use of solid-state electrodes for oxidizing different kind of compound, that could lead to the synthesis of chemicals, bioremediation of polluted matrices, the treatment of contaminants of interest, as well as the recovery of energy. Keeping in mind those possibilities, since the beginning of the present century, there has been a growing interest in the use of electrochemical technologies for wastewater treatment, and if possible with simultaneous power generation. In the last years, there has been a growing interest to explore the possibility of merging MET with constructed wetlands, to offer a new option of intensified wetland system that could keep a high performance with a lower footprint. Based on that interest, this paper explains the general principles of MET, and the different known extracellular electron transfer mechanisms ruling the interaction between electroactive bacteria and potential solid-state electron acceptors. Also, the adoption of those principles for the development of MET set-ups for simultaneous wastewater treatment and power generation, and the challenges that the technology face. Ultimately, the most recent developments in set-ups that merges MET with constructed wetlands are presented and discussed.

Abhimanyu Sharma, Karan Singh, HarKamal Singh et al.

Resource Recovery from Industrial Wastewater through Microbial Electrochemical Technologies • 2024

The high salinity and complicated chemical makeup of industrial effluent create a serious threat to the environment. Traditional treatment procedures are not always successful in eradicating water impurities, whereas desalination operations can be both expensive and requires a lot of energy usage. To deal with that, microbial desalination cell (MDC) technology has emerged as a viable option in recent years for the purification of industrial wastewater. The purpose of this chapter is to introduce readers to MDCs and their potential uses in industrial wastewater treatment by discussing their basic concepts, essential parts, performance evaluation, and potential in the future. In addition, the challenges and prospective strategies for enhancing MDC effectiveness and commercial viability are discussed.

Sudeep Popat, Prathap Parameswaran, César Torres

ECS Meeting Abstracts • 2014

Anode-respiring bacteria (ARB) catalyze the complete oxidation of organic compounds (e.g. acetate, glucose) into electrical current and carbon dioxide. ARB produce a biofilm at the electrode surface, where even cells on the outer part of the biofilm are participating in current production. Our team uses a variety of electrochemical techniques in order to characterize electron transport responses from various ARB. Through these experiments, we have observed a complex response to anode potential that allows ARB, such as G. sulfurreducens , to optimize their efficiency in electron transport. Identifying this complex behavior allows us to better understand and predict the response of ARB to different conditions in microbial electrochemical cells (MXCs). While the topic of electron transport is the focus of most ARB research, ionic transport is the most important factor in determining rate-limiting and potential loss processes. ARB require near-neutral pH in the medium to grow, differing from chemical fuel cells commonly employed, which run under acidic or alkaline conditions. This pH requirement results in a major transport limitation, as H + ions (now in mM range) should be transported from anode to cathode to achieve electron neutrality. In an MXC anode, H + ions accumulate in the ARB biofilm, creating an acidification that limits current generation. We have identified and characterized ARB that work outside the neutral pH range, including Geoalkalibacter ferrihydriticus and Thermoanaerobacter pseudethanolicus , that allow us to operate MXCs at either acidic or basic conditions. Meanwhile, at the cathode, local gradients leading to pH > 12 is typical in MXC operation. As a consequence, the pH gradient results in Nernstian concentration overpotential of > 300 mV. Thus, understanding and controlling ionic transport in MXCs is essential to ensure an efficient operation. I will discuss our current efforts to characterize and overcome ionic transport limitations in order to develop efficient MXC processes.

Felipe Ernesto Torres Rojas

• 2022

Esta tesis interdisciplinaria combina el estudio de los principios fundamentales biológicos, químicos y físicos de los microorganismos reductores de perclorato electroquímicamente activos con el diseño y la ingeniería para desarrollar reactores bioelectroquímicos para el tratamiento sostenible de dos contaminantes emergentes en el agua: perclorato y clorato. Para lograr este objetivo, primero, se evaluaron las capacidades electroactivas de Dechloromonas sp. CS-1, Clostridiodales sp. CS-2, Paenibacillus sp. CS-3 y Oerskovia sp. CS-4. Estas bacterias aisladas de un sitio natural del norte de Chile solo en Dechloromonas sp. CS-1 y Clostridiodales sp. CS-2 exhibieron una respuesta electroactiva por voltamperometría cíclica obteniendo peaks de corriente a -651 mV y -303 mV (vs. Ag / AgCl), respectivamente. Cada bacteria se probó en una BER mediante la realización de una prueba de cronoamperometría a un potencial de -550 mV vs. Ag / AgCl durante seis días. El estudio electroquímico demostró una eficiencia coulómbica (EC) de 93,328% y 45,643% con una tasa de eliminación de 26,721 ± 2,934 mg L-1 día-1 y 17,289 ± 1,032 mg L -1 día-1, respectivamente. Los resultados sugieren una reducción completa de perclorato para CS-1 (es decir, reacción de 8 electrones) y una reducción incompleta para CS-2 (es decir, reacción de 2 electrones). Este trabajo pionero de bioprospección reveló la actividad electroactiva de Dechloromonas sp. CS-1 y Clostridiodales sp. CS-2 sin el uso de transportadores electroquímicos para la reducción de perclorato. En segundo lugar, se demostró la reducción bioelectroquímica del clorato utilizando BER con un voltaje de aplicación de 0,4 Volt. Los BER ensayados se inocularon con D. agitata CKB. Un experimento de 44 días en el modo de flujo ascendente de recirculación reveló una salida de corriente y eliminación de clorato de 1,54 ± 0,26 µA y 251,5 ± 76,1 mg L-1 respectivamente. Luego, las BER se operaron en modo discontinuo durante 71 días, aumentando el rendimiento a 4,49 ± 0,70 µA y 607,3 ± 64,5 mg L-1. La caracterización electroquímica reveló un pico catódico a -550 ± 8 mV vs. Ag / AgCl y un cálculo de 6 electrones involucrados en la reacción de biorreducción del clorato. A través de este estudio, fue posible establecer, por primera vez, el mecanismo bioelectroquímico de reducción de clorato por D. agitata. Finalmente, se llevó a cabo una modificación química en el electrodo de carbono para mejorar el rendimiento de los BERs utilizados para eliminar estos oxianiones. De acuerdo con la espectroscopía de fotoelectrones de rayos X, la espectroscopía RAMAN y la espectroscopía IR, fue posible describir la funcionalización del electrodo de la tela de carbono. Los resultados muestran que la modificación fue principalmente de los grupos carboxilados (-COOH, -C-O-C-) y nitrogenados (-NH3)+. El electrodo modificado se utilizó en un BER inoculado con Dechloromnoas sp. CS-1, demostrando una mejor respuesta que los controles sin tratamiento durante una prueba de cronoamperometría de 17 días, aplicando un potencial de -500 mV vs Ag / AgCl. El BER con el electrodo modificado mostró una EC de 90,794 ± 9,157% y una tasa de reducción de perclorato de 0,345 ± 0,007 mol m-3 día-1 que fue superior a otros informes en la literatura. Por lo tanto, estos resultados muestran la sinergia positiva entre los microorganismos reductores de perclorato electroactivo y los electrodos modificados para mejorar las BER y eliminar los oxianiones del agua. Luego, al combinar estos tres capítulos (artículos), esta tesis tiene el objetvo de introducir o guiar el camino para el desarrollo de nuevas tecnologías electroquímicas microbianas sostenibles destinadas a eliminar el perclorato y el clorato del agua.

Jingyu Wang, Yongchao Xie, Yi Chen et al.

ChemRxiv • 2024

Most microorganisms grow in assemblages with chemical gradients that influence, and are influenced by, metabolism. pH gradient plays an important role in various metabolism processes. Understanding the effects of the pH gradient on metabolism and regulation within microbial assemblages is important for microbial physiology. However, the complexity of the microbial environment makes it hard to decouple the effect of the pH gradient from other species. Therefore, an artificial pH gradient is required to reveal the correlation of the pH gradient and microbial physiology. Here, we demonstrated a controllable pH gradient plate by using electrochemical proton coupled electron transfer reaction based on interdigital electrodes. The morphology design of the interdigital electrodes enables a pH gradient at the level of 10 micrometers, which was demonstrated under confocal microscope with a resolution of 1 micrometer. The electrochemical system also achieved a fast time response of ten seconds. In summary, this platform provided a flexible pH gradient with a high spatial and temporal resolution.