Fabian Kubannek, Simone Thiel, Boyke Bunk et al.

ChemElectroChem • 2020

<jats:title>Abstract</jats:title><jats:p>An effectively operating microbial electrolysis cell requires an inexpensive electron donor in combination with a defined and stable electron‐transferring microbial community. Here, a defined co‐culture of <jats:italic>Raoultella electrica</jats:italic> and <jats:italic>Geobacter sulfurreducens</jats:italic> was established to generate current during glycerol oxidation. Maximum current densities of 0.20 mA cm<jats:sup>−2</jats:sup> and coulombic efficiencies of 21 % were achieved. Glycerol metabolization into acetate by <jats:italic>R. electrica</jats:italic> and further acetate utilization by the current‐producing <jats:italic>G. sulfurreducens</jats:italic> were detected. Based on these observations, a physico‐chemical model was established and used to describe quantitatively the relationships between current density, metabolite concentrations and bacterial growth. The competition for acetate between <jats:italic>G. sulfurreducens</jats:italic> and <jats:italic>R. electrica</jats:italic> was identified as the major limitation of the system. This detailed quantitative understanding of the physiological interactions opens the door for target‐oriented genetic engineering of the microbes.</jats:p>

R. Chung, Eunice Y. Kang, Y. Shin et al.

Journal of Sustainable Bioenergy Systems • 2019

Microbial fuel cells (MFCs) are bioelectrochemical systems that convert chemical energy contained in organic matter into electrical energy by using the catalytic (metabolic) activity of living microorganisms. Mediator-less two chamber H-type MFCs were constructed in the current study, using dairy digester microbial population as anode inocula to convert finely ground pine tree (Avicel) at 2% (w/v) to electricity. MFCs were placed at 37°C and after the circuit voltage was stabilized on d9, bovine rumen microorganisms cultured anaerobically for 48 hrs in cellulose broth media were added to treatment group of MFC at 1% v/v dosage. MFC power and current across an external resistor were measured daily for 10 d. At the end of incubation on d19 head space gas and anode chamber liquid solutions were collected and analyzed for total gas volume and composition, and volatile fatty acids, respectively. Addition of enriched rumen microorganisms to anaerobic anode chamber increased cellulose digestibility and increased both CO2 and methane production; however, it decreased the methane to CO2 ratio. Over the experimental period, electricity generation was increased with rumen microorganism addition, and power density normalized to anode surface area was 17.6 to 67.2 mW/m2 with average of 36.0 mW/m2 in treatment, while control group had 3.6 to 21.6 (AVE 12.0) mW/m2. These observations imply that biocatalysis in MFCs requires additional cellulolytic activities to utilize structural biomass in bioenergy production.

M. Kizling, M. Dzwonek, A. Nowak et al.

Nanomaterials • 2020

A significant problem still exists with the low power output and durability of the bioelectrochemical fuel cells. We constructed a fuel cell with an enzymatic cascade at the anode for efficient energy conversion. The construction involved fabrication of the flow-through cell by three-dimensional printing. Gold nanoparticles with covalently bound naphthoquinone moieties deposited on cellulose/polypyrrole (CPPy) paper allowed us to significantly improve the catalysis rate, both at the anode and cathode of the fuel cell. The enzymatic cascade on the anode consisted of invertase, mutarotase, Flavine Adenine Dinucleotide (FAD)-dependent glucose dehydrogenase and fructose dehydrogenase. The multi-substrate anode utilized glucose, fructose, sucrose, or a combination of them, as the anode fuel and molecular oxygen were the oxidant at the laccase-based cathode. Laccase was adsorbed on the same type of naphthoquinone modified gold nanoparticles. Interestingly, the naphthoquinone modified gold nanoparticles acted as the enzyme orienting units and not as mediators since the catalyzed oxygen reduction occurred at the potential where direct electron transfer takes place. Thanks to the good catalytic and capacitive properties of the modified electrodes, the power density of the sucrose/oxygen enzymatic fuel cells (EFC) reached 0.81 mW cm−2, which is beneficial for a cell composed of a single cathode and anode.

H. Lloyd-Laney, N. Yates, James Stapleton et al.

ECS Meeting Abstracts • 2023

Electron transfer and redox chemistry drives life and Biology can provide inspiration for the design of sustainable fuel catalysts that achieve highly active and selective small molecule transformations. In particular, the Parkin group are interested in hydrogenases,1 biological H2-producing enzymes, and lytic polysaccharide monooxygenases (LPMOs),2, 3 enzymes that breakdown cellulose. We seek to understand how the rate and energetics of electron transfer controls catalysis in such enzymes;4 to do this we collaborate with the Gavaghan and Bond groups to develop more powerful bioelectrochemical methodologies.5 This talk will describe our most recent efforts to integrate sinusoidal voltammetry into our enzyme-electrochemistry toolkit.6, 7 The technique offers advantages in terms of simulation speed, which in turn enables the powerful application of Bayesian statistical analysis to visualise the uncertainty in the modelling approach. However, we still rely on large amplitude Fourier transform voltammetry and direct current methodologies to visualise the Faradaic current and readily define redox reaction parameter bounds. References: [1] H. Adamson, M. Robinson, J. J. Wright, L. A. Flanagan, J. Walton, D. Elton, D. J. Gavaghan, A. M. Bond, M. M. Roessler and A. Parkin, J. Am. Chem. Soc., 2017, 139, 10677-10686. [2] P. J. Lindley, A. Parkin, G. J. Davies and P. H. Walton, Faraday Discuss., 2022, 234, 336-348. [3] J. Branch, B. S. Rajagopal, A. Paradisi, N. Yates, P. J. Lindley, J. Smith, K. Hollingsworth, W. B. Turnbull, B. Henrissat, A. Parkin, A. Berry and G. R. Hemsworth, Biochem. J., 2021, 478, 2927-2944. [4] A. R. Dale-Evans, M. J. Robinson, H. O. Lloyd-Laney, D. J. Gavaghan, A. M. Bond and A. Parkin, Front. Chemistry, 2021, 9. [5] H. Adamson, A. M. Bond and A. Parkin, Chem. Comm., 2017, 53, 9519-9533. [6] H. O. Lloyd-Laney, N. D. J. Yates, M. J. Robinson, A. R. Hewson, J. D. Firth, D. M. Elton, J. Zhang, A. M. Bond, A. Parkin and D. J. Gavaghan, Anal. Chem., 2021, 93, 2062-2071. [7] H. O. Lloyd-Laney, N. D. J. Yates, M. J. Robinson, A. R. Hewson, J. Branch, G. R. Hemsworth, A. M. Bond, A. Parkin and D. J. Gavaghan, Journal of Electroanalytical Chemistry, 2023, 935, 117264.

Jiao Li, Xiyun Feng, Yi Jia et al.

Journal of Materials Chemistry A • 2017

Photosystem II (PSII), as the only enzyme to catalyze the light-induced water oxidation reaction in the natural photosynthesis system, is introduced to fabricate artificial solar conversion systems with an intensive photo-to-current efficiency to convert solar energy into electrical power. In this research, we report a hybrid photo-bioelectrochemical system consisting of PSII isolated from spinach leaves that is co-assembled in nanotubular indium–tin oxide (ITO) multilayer films pasted on the commercial ITO substrate as a photoanode, which presents enhanced photocurrent responses as high as 2.4 μA cm−2 (mediator-free) and 39 μA cm−2 (with mediator) under white light irradiation (λ < 800 nm) using a xenon lamp as the light source. In this photoanode system, the three-dimensional (3D) hierarchical porous nanotubular ITO film was synthesized through a layer-by-layer (LBL) self-assembly process using a natural cellulose substance (e.g., filter paper) as a template. The specific structure, and good optical and electrical properties of the hierarchical nanotubular ITO allow for an increased protein loading as high as 166 pmol PSII cm−2 and an enhanced photocurrent by about 78 times compared with the bare PSII photoanode. This biomimetic template fabrication method of ITO materials with unique morphologies and desirable properties provides an effective assembly strategy for PSII-based hybrid photoanode systems for solar energy conversion.

Jiao Li, Xiyun Feng, J. Fei et al.

Journal of Materials Chemistry A • 2016

The fabrication of artificial photosynthetic systems to convert solar energy into electrical power is of great importance to meet human needs for energy; photosystem II (PSII), the core enzyme for water splitting in natural solar energy conversion processes can be introduced for this purpose. However, there remain significant challenges in the facile preparation of such semi-artificial photoanode systems with enhanced photocurrent responses. Herein we report a hybrid photoanode system consisting of PSII from spinach integrated into an indium-tin oxide electrode modified with nanotubular titania that is synthesized by using cellulose paper as a scaffold. This electrode provides a well-defined hierarchical nanostructure for protein loading, and the fine titania nanocrystals facilitate electron transfer from PSII to the electrode. The resulting semiconductor–protein hybrid photo-bioelectrochemical system enhances direct electron transfer (1.3 μA cm−2) and mediated electron transfer (10.6 μA cm−2) photocurrents.

R. Latonen, J. Cabrera, S. Lund et al.

ACS Applied Bio Materials • 2020

Electrically conductive composite nanofibers were fabricated using poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT-PSS) and cellulose nanofibrils (CNFs) via the electrospinning technique. Poly(ethylene oxide) (PEO) was used to assist the electrospinning process, and poly(ethylene glycol) diglycidyl ether was used to induce chemical cross-linking, enabling stability of the formed fibrous mats in water. The experimental parameters regarding the electrospinning polymer dispersion and electrospinning process were carefully studied to achieve a reproducible method to obtain bead-free nanofibrous mats with high stability after water contact, with an electrical conductivity of 13 ± 5 S m-1, thus making them suitable for bioelectrochemical applications. The morphology of the electrospun nanofibers was characterized by scanning electron microscopy, and the C/S ratio was determined with energy dispersive X-ray analysis. Cyclic voltammetric studies showed that the PEDOT-PSS/CNF/PEO composite fibers exhibited high electroactivity and high stability in water for at least two months. By infrared spectroscopy, the slightly modified fiber morphology after water contact was demonstrated to be due to dissolution of some part of the PEO in the fiber structure. The biocompatibility of the PEDOT-PSS/CNF/PEO composite fibers when used as an electroconductive substrate to immobilize microalgae and cyanobacteria in a photosynthetic bioelectrochemical cell was also demonstrated.

A. A. Yaqoob, Mohamad Nasir Mohamad Ibrahim, K. Umar et al.

Polymers • 2020

Benthic microbial fuel cells (BMFCs) are considered to be one of the eco-friendly bioelectrochemical cell approaches nowadays. The utilization of waste materials in BMFCs is to generate energy and concurrently bioremediate the toxic metals from synthetic wastewater, which is an ideal approach. The use of novel electrode material and natural organic waste material as substrates can minimize the present challenges of the BMFCs. The present study is focused on cellulosic derived graphene-polyaniline (GO-PANI) composite anode fabrication in order to improve the electron transfer rate. Several electrochemical and physicochemical techniques are used to characterize the performance of anodes in BMFCs. The maximum current density during polarization behavior was found to be 87.71 mA/m2 in the presence of the GO-PANI anode with sweet potato as an organic substrate in BMFCs, while the GO-PANI offered 15.13 mA/m2 current density under the close circuit conditions in the presence of 1000 Ω external resistance. The modified graphene anode showed four times higher performance than the unmodified anode. Similarly, the remediation efficiency of GO-PANI was 65.51% for Cd (II) and 60.33% for Pb (II), which is also higher than the unmodified graphene anode. Furthermore, multiple parameters (pH, temperature, organic substrate) were optimized to validate the efficiency of the fabricated anode in different environmental atmospheres via BMFCs. In order to ensure the practice of BMFCs at industrial level, some present challenges and future perspectives are also considered briefly.

Anjana Ratheesh, B. R. Sreelekshmy, Anil Kumar T R et al.

ACS Applied Bio Materials • 2025

Lignocellulose recalcitrance remains a significant economic challenge in modern biomass conversion processes. Microbial strategies offer considerable promise for ecofriendly bioenergy generation. This study presents an advanced integrated approach that combines bacterial treatment with a bioelectrochemical system (BES) to enhance the conversion efficiency of lignocellulosic biomass. Unlike integrated or sequential approaches, a comparative evaluation of two distinct pretreatment strategies, alkaline delignification and biological treatment, was conducted independently to assess their individual effectiveness in sugar cane bagasse (SCB) degradation and their performance in a microbial fuel cell (MFC). Biological treatment with B. subtilis alone yielded superior outcomes in terms of saccharification efficiency, microbial growth, and bioelectricity generation, as evidenced by higher open-circuit potentials in MFC half-cell studies in comparison with alkali delignified SCB. Notably, B. subtilis treatment increased cellulose content by 72% and reduced hemicellulose and lignin by approximately 0.84-fold, indicating effective enzymatic action. Metabolomic profiling identified 2846 metabolites that significantly diverged between the experimental groups. Notably, lignin-derived compounds such as ferulic acid, syringic acid, and p-coumaric acid were detected at elevated levels, confirming enhanced ligninase activity in pretreated SCB. Additionally, the presence of organic acids (e.g., acetic acid), amino acids, and their derivatives, resulting from the breakdown of cellulose, hemicellulose, and lignin, provided essential bioenergy substrates for exoelectrogenic organisms in BESs. This integration led to a maximum power density of 353 ± 5 mW/m2 and a current density of 200 ± 3 mA/m2, demonstrating significant enhancement in performance of MFC. Furthermore, the biotransformation of SCB facilitated the channeling of metabolites into value-added products, increasing the overall efficiency of the biomass valorization. Thus, the rational utilization of SCB underscores its potential for scalable biorefinery applications and its broader implications for sustainable bioenergy production.

Euntae Yang, Kyoung-Yeol Kim, K. Chae et al.

Desalination and Water Treatment • 2016

AbstractRecent forward osmosis–bioelectrochemical hybrid systems (FO-BESs) have been designed to simultaneously produce bio-energy and clean water from wastewater. Asymmetric forward osmosis (FO) membranes are a crucial component for determining FO-BES performance, but only cellulose triacetate (CTA NW) membranes in the same orientation have been applied to FO-BESs. In this work, both CTA NW and polyamide (PA) membranes were tested in two membrane orientations (active layer facing feed solution or anolyte and support layer facing feed solution). For an in-depth understanding of the FO membranes, properties were investigated using scanning electron microscopy, contact angle, impedance spectroscopy, and proton transport analyses. The electricity generation and water extraction in FO-BESs having these two FO membranes in different orientations were then evaluated. Based on membrane characterization, PA seemed to be a proper membrane for the FO-BES because of higher hydrophilicity, lower membrane thickness, l...

Stanisław Ledakowicz

Energies • 0

<jats:p>After a brief characterisation of lignocellulosic biomass (LCB) in terms of its biochemical structure and the pretreatment techniques used to disrupt lignin structure and decrystallise and depolymerise cellulose, this review considers five main pathways for biochemical biomass conversion: starting with anaerobic digestion to convert various LCB feedstocks into bioproducts; considering the integration of biochemical and thermochemical processes, syngas fermentation, which has been recently developed for biofuel and chemical production, is reviewed; the production of 2G bioethanol and biobutanol from LCB waste is discussed; the literature on biohydrogen production by dark fermentation, photofermentation, and bioelectrochemical processes using microbial electrolysis cells as well as hybrid biological processes is reviewed. The conclusions and future prospects of integrating biochemical and thermochemical conversion processes of biomass are discussed and emphasised.</jats:p>

Dan Sun, Xinyuan Wan, Wenzong Liu et al.

RSC Advances • 0

<p><italic>Geobacter anodireducens</italic>is unique in that it can generate high current densities in bioelectrochemical systems (BES) operating under high salt conditions.</p>

Fei Zhao, Elizabeth S. Heidrich, Thomas P. Curtis et al.

Applied Microbiology and Biotechnology • 2020

<jats:title>Abstract</jats:title><jats:p>Anode potential can affect the degradation pathway of complex substrates in bioelectrochemical systems (BESs), thereby influencing current production and coulombic efficiency. However, the intricacies behind this interplay are poorly understood. This study used glucose as a model substrate to comprehensively investigate the effect of different anode potentials (− 150 mV, 0 mV and + 200 mV) on the relationship between current production, the electrogenic pathway and the abundance of the electrogenic microorganisms involved in batch mode fed BESs. Current production in glucose-acclimatized reactors was a function of the abundance of <jats:italic>Geobacteraceae</jats:italic> and of the availability of acetate and formate produced by glucose degradation. Current production was increased by high anode potentials during acclimation (0 mV and + 200 mV), likely due to more <jats:italic>Geobacteraceae</jats:italic> developing. However, this effect was much weaker than a stimulus from an artificial high acetate supply: acetate was the rate-limiting intermediate in these systems. The supply of acetate could not be influenced by anode potential; altering the flow regime, batch time and management of the upstream fermentation processes may be a greater engineering tool in BES. However, these findings suggest that if high current production is the focus, it will be extremely difficult to achieve success with complex waste streams such as domestic wastewater.</jats:p>

Deng Wang, Ying Wang, Jing Yang et al.

Polymers • 0

<jats:p>The flavin-based indirect electron transfer process between electroactive bacteria and solid electrode is crucial for microbial fuel cells (MFCs). Here, a cellulose-NaOH-urea mixture aerogel derived hierarchical porous carbon (CPC) is developed to promote the flavin based interfacial electron transfer. The porous structure of the CPC can be tailored via adjusting the ratio of urea in the cellulose aerogel precursor to obtain CPCs with different type of dominant pores. According to the electrocatalytic performance of different CPC electrodes, the CPCs with higher meso- and macropore area exhibit greatly improved flavin redox reaction. While, the CPC-9 with appropriate porous structure achieves highest power density in Shewanella putrefaciens CN32 MFC due to larger active surface for flavin mediated interfacial electron transfer and higher biofilm loading. Considering that the CPC is just obtained from the pyrolysis of the cellulose-NaOH-urea aerogel, this work also provides a facile approach for porous carbon preparation.</jats:p>

Mehran Abbaszadeh Amirdehi, Sokunthearath Saem, Mir Pouyan Zarabadi et al.

Advanced Materials Interfaces • 2018

<jats:title>Abstract</jats:title><jats:p>A method for producing hierarchical wrinkled gold surfaces is used to continuously change characteristic microstructure dimensions of a bioanode in a microbial fuel cell, while conserving the total electroactive surface area and material chemistry. Using this approach, the effect of anode topography on power outputs from direct electron transfer from <jats:italic>Geobacter sulfurreducens</jats:italic> biofilms can be isolated and studied without the competing effects associated with additive manufacturing. Despite having the same electroactive surface area for all structured anodes, tall and well‐spaced features perform best. Anodes with the shortest, most closely packed structures, on the other hand, do not perform any better than planar surfaces with the same footprint and lower electroactive surface area. It is postulated that large interfold spacing provides better electrical contact between the biofilm and the electrode via improved bacterial packing density at the electrode surface. Rigorous attention to structural dimensions rather than total electroactive surface area is proposed as an important direction for future bioanode optimization in microbial fuel cells containing direct electron transfer electroactive biofilms.</jats:p>

Shaofeng Zhou, Da Song, Ji-Dong Gu et al.

Frontiers in Microbiology • 0

<jats:p>The overlap of microbiology and electrochemistry provides plenty of opportunities for a deeper understanding of the redox biogeochemical cycle of natural-abundant elements (like iron, nitrogen, and sulfur) on Earth. The electroactive microorganisms (EAMs) mediate electron flows outward the cytomembrane<jats:italic>via</jats:italic>diverse pathways like multiheme cytochromes, bridging an electronic connection between abiotic and biotic reactions. On an environmental level, decades of research on EAMs and the derived subject termed “<jats:italic>electromicrobiology</jats:italic>” provide a rich collection of multidisciplinary knowledge and establish various bioelectrochemical designs for the development of environmental biotechnology. Recent advances suggest that EAMs actually make greater differences on a larger scale, and the metabolism of microbial community and ecological interactions between microbes play a great role in bioremediation processes. In this perspective, we propose the concept of microbial electron transfer network (METN) that demonstrates the “species-to-species” interactions further and discuss several key questions ranging from cellular modification to microbiome construction. Future research directions including metabolic flux regulation and microbes–materials interactions are also highlighted to advance understanding of METN for the development of next-generation environmental biotechnology.</jats:p>

Joseph Oram, Lars J. C. Jeuken

ChemElectroChem • 2016

<jats:title>Abstract</jats:title><jats:p>Exoelectrogenic bacteria can couple their metabolism to extracellular electron acceptors, including macroscopic electrodes, and this has applications in energy production, bioremediation and biosensing. Optimisation of these technologies relies on a detailed molecular understanding of extracellular electron‐transfer (EET) mechanisms, and <jats:italic>Shewanella oneidensis</jats:italic> MR‐1 (MR‐1) has become a model organism for such fundamental studies. Here, cyclic voltammetry was used to determine the relationship between the surface chemistry of electrodes (modified gold, ITO and carbon electrodes) and the EET mechanism. On ultra‐smooth gold electrodes modified with self‐assembled monolayers containing carboxylic‐acid‐terminated thiols, an EET pathway dominates with an oxidative catalytic onset at 0.1 V versus SHE. Addition of iron(II)chloride enhances the catalytic current, whereas the siderophore deferoxamine abolishes this signal, leading us to conclude that this pathway proceeds via an iron mediated electron transfer mechanism. The same EET pathway is observed at other electrodes, but the onset potential is dependent on the electrolyte composition and electrode surface chemistry. EET pathways with onset potentials above −0.1 V versus SHE have previously been ascribed to direct electron‐transfer (DET) mechanisms through the surface exposed decaheme cytochromes (MtrC/OmcA) of MR‐1. In light of the results reported here, we propose that the previously identified DET mechanism of MR‐1 needs to be re‐evaluated.</jats:p>

Aiichiro Fujinaga, Kamin Tei, H. Ozaki et al.

Journal of Water and Environment Technology • 2016

The graphite powder was added to a microbial fuel cell (MFC) that uses soil to decrease the internal resistance and increase the electric power and electric charge (ampere hour: Ah). The effect of adding the graphite powder to soil MFC is evaluated by experiment and simulation using mathematical models. In this experiment, the total weight of the reddish granular soil and the graphite powder was 1000 g, and ratios of the graphite were set to five values between 0% and 20% by weight. The grain size of the soil was between 3 and 8 mm. The diameter of electrode was 9 cm. The initial chemical oxygen demand (COD) of synthetic wastewater was 1400 mg/L. As a result, the amount of Ah was maximized when 10% of the graphite was mixed. When the amount of the graphite increased, the internal resistance decreased; however, consumption of COD decreased and the microbial reaction decreased. This might be because the graphite covers the surface of the soil, and it disturbs the adsorption of the soil and decreases the biofilms. Therefore, a suitable proportion of the graphite exists, and it was approximately 10% in this experiment.

Ting Liu, Yangyang Yu, Dongzhe Li et al.

RSC Advances • 2016

External resistance is one of the important factors that affect the performance of microbial fuel cells (MFCs). In this study, bioelectrochemical and biofilm characterization was conducted for Shewanella oneidensis MR-1 inoculated MFCs with 250 Ω, 500 Ω, 2 kΩ, 6 kΩ and 22 kΩ resistors. Overall, a smaller external resistance resulted in a higher maximum power density and more riboflavin secretion. A maximum power density of 136.8 ± 3.1 mW m−2 was achieved when MFCs were operated with a 500 Ω resistor, which was 3.7 times that with a 22 kΩ resistor. Electrochemical impedance spectra (EIS) analysis verified an increased internal resistance with a higher external resistance. Meanwhile, more biofilm mass and extracellular polymer substances (EPS) were confirmed on the MFC anode with a higher external resistance.

Luisa Alvarez-Benítez, S. Silva-Martínez, Alfredo Hernandez-Perez et al.

Catalysts • 2022

Anaerobic biodegradation of petroleum-contaminated sediments can be accomplished by a sediment microbial fuel cell (SMFC), but the recovered energy is very low (~4 mW m−2). This is due to a high internal resistance (Ri) that develops in the SMFC. The evaluation of the main experimental parameters that contribute to Ri is essential for developing a feasible SMFC design and this task is normally performed by electrochemical impedance spectroscopy (EIS). A faster and easier alternative procedure to EIS is to fit the SMFC polarization curve to an electrochemical model. From there, the main resistance contributions to Ri are partitioned. This enables the development of a useful procedure for attaining a low SMFC Ri while improving its power output. In this study, the carbon-anode surface was increased, the biodegradation activity of the indigenous populations was improved (by the biostimulation method, i.e., the addition of kerosene), the oxygen reduction reaction was catalyzed, and a 0.8 M Na2SO4 solution was used as a catholyte at pH 2. As a result, the initial SMFC Ri was minimized 20 times, and its power output was boosted 47 times. For a given microbial fuel cell (MFC), the main resistance contributions to Ri, evaluated by the electrochemical model, were compared with their corresponding experimental results obtained by the EIS technique. Such a validation is also discussed herein.

Xiaojun Jin, Nuan Yang, Dake Xu et al.

Frontiers in Bioengineering and Biotechnology • 2024

Bioelectrochemical systems are sustainable and potential technology systems in wastewater treatment for nitrogen removal. The present study fabricated an air-cathode denitrifying microbial fuel cell (DNMFC) with a revisable modular design and investigated metabolic processes using nutrients together with the spatiotemporal distribution characteristics of dominated microorganisms. Based on the detection of organics and solvable nitrogen concentrations as well as electron generations in DNMFCs under different conditions, the distribution pattern of nutrients could be quantified. By calculation, it was found that heterotrophic denitrification performed in DNMFCs using 56.6% COD decreased the Coulombic efficiency from 38.0% to 16.5% at a COD/NO3 −-N ratio of 7. Furthermore, biological denitrification removed 92.3% of the nitrate, while the residual was reduced via electrochemical denitrification in the cathode. Correspondingly, nitrate as the electron acceptor consumed 16.7% of all the generated electrons, and the residual electrons were accepted by oxygen. Microbial community analysis revealed that bifunctional bacteria of electroactive denitrifying bacteria distributed all over the reactor determined the DNMFC performance; meanwhile, electroactive bacteria were mainly distributed in the anode biofilm, anaerobic denitrifying bacteria adhered to the wall, and facultative anaerobic denitrifying bacteria were distributed in the wall and cathode. Characterizing the contribution of specific microorganisms in DNMFCs comprehensively revealed the significant role of electroactive denitrifying bacteria and their cooperative relationship with other functional bacteria.

I. R. Garduño‐Ibarra, Shruti Tanga, Alexandra Tsitouras et al.

Journal of Chemical Technology &amp; Biotechnology • 2024

This study focuses on the treatment of brewery waste slurries (BWS) with high chemical oxygen demand (COD) using a single‐chamber microbial fuel cell (MFC) inoculated with heat‐treated anaerobic seed sludge. A co‐substrate of 5 g L−1 glycerol was added, and carbon felt (CF) was employed as the anode material, enhanced through in situ polymerization of aniline (PANI/CF). Additionally, the adsorption of ruthenium dioxide nanoparticles onto the modified CF was assessed (PANI‐RO/CF).Tests conducted at room temperature (19 °C to 22 °C) achieved an average COD reduction of 36%. The PANI‐RO/CF electrode accumulated 24% more charge, resulting in the highest coulombic efficiency of 75.1%, significantly exceeding similar studies. However, the PANI‐modified anode generated more energy, exceeding that of the bare CF by more than double, reaching 57.1 mW m−2. An optimized working volume was identified in relation to other reported works. Microbial population analysis revealed an interaction between Staphylococcus epidermidis and a rarely reported psychrophilic Bacillus species. After 30 h, lactic acid emerged as the main by‐product, with a concentration of 7.5 ± 0.6 g L−1.These findings highlight an optimization approach based on cell configuration and inoculum selection, as well as a significant valorization pathway that is frequently overlooked in the existing literature on brewery wastewater treatment using MFCs, particularly regarding the attractiveness of lactic acid production. © 2024 The Author(s). Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Matthew Kwofie, Bright Amanful, Samuel Gamor et al.

International Journal of Energy Research • 2024

This paper reviews the current state of microbial fuel cell (MFC) technology for energy generation. It begins by exploring clean energy alternatives, focusing on waste‐to‐energy solutions, and introduces the concept, applications, and advantages of MFCs. The biochemical processes within MFCs are explained, highlighting how microorganisms metabolize substrates through glycolysis, the Krebs cycle, and the electron transport chain to generate electrons. These electrons flow through an external circuit and combine with protons and oxygen at the cathode to produce water or reduced forms of nitrogen and sulfur. This paper also analyzes 10 key parameters affecting MFC performance: coulombic efficiency, pH, temperature, substrates, organic loading rate, electrode potential, open circuit voltage, treatment efficiency, organic removal rate, and hydraulic retention time. Recent advancements in MFC technology are also discussed, including innovations in reactor configuration and scaling, the development of new membrane materials like earthen and ceramic, and improvements in wastewater treatment methods. The advancements also extend to genetic engineering techniques to enhance microbial efficiency and component modifications, such as the use of carbon‐based nanomaterials and metal catalysts for improved performance, innovations in proton transfer membranes, and mediator‐less MFCs utilizing metal‐reducing bacteria. Challenges facing MFC technology, such as cost, scalability, and environmental sensitivity, are mentioned. The paper concludes with future directions, including the use of advanced materials, integration with wastewater treatment infrastructure, and the potential for nutrient recovery and chemical synthesis. This comprehensive review aims to provide knowledge into optimizing MFCs for sustainable energy generation and environmental benefits.

Xiaoou Wang, Ming Xue, Zhaoyu Wang et al.

Water • 2024

This study designed integrated constructed wetland–microbial fuel cell (CW–MFC) systems using activated carbon (AC) as both CW substrates and MFC anodes and investigated the structure-activity relationship of six kinds of commercial columnar AC, as well as the organics and nitrogen removal, microbial activity and diversity of CW–MFCs. Results showed that the nitrogen adsorption by AC tended to be a linear process in which physical adsorption played a leading role and micropores made great contributions. A higher specific surface area, developed mesopores, and oxygen functionalities were conducive to the capacitance properties of AC, while a higher specific surface area and developed micropores were conducive to reduce material resistance and improve ion permeability. Coconut-shell-based AC had both excellent nitrogen adsorption capacity and electrochemical properties, making it ideal as both CW substrates and MFC anodes for CW–MFCs. The electricity generation, coulombic efficiency, internal resistance, and organics and nitrogen removal of CW–MFCs were positively correlated with the total depth of AC anodes. The total depth of AC anodes can be determined based on the influent organics/nitrogen loadings and organics/nitrogen removal load of AC, and a relatively smaller depth of a single AC anode (5 cm) was recommended. The MFC effectively improved the enzymatic activity (by 10.33% dehydrogenase, 8.72% catalase, and 7.35% ammonia monooxygenase), nitrification/denitrification intensity (by 9.53%/6.68%), and microbial diversity (by 1.64–4.07%) of AC (MFC anodes) in CW–MFCs, while the depth of a single AC anode barely influenced the microbial activity and diversity. MFCs increased COD and NH3-N removal in CW–MFCs by 11.60% and 3.4%, respectively. The increased total adsorption capacity of AC with the increase of its total depth narrowed the difference in COD removal resulting from the promotion of MFCs on organics degradation. MFCs increased TN removal in CW–MFCs by 5.29% through promoting denitrification in cathodes and enhancing NH3-N assimilation in anodes. The phyla of EAB (Proteobacteria, Bacteroidetes, Firmicutes, and Acidobacteria) and genera of EAB (Citrobacter, Geobacter, and Pseudomonas) accounted for 85–86% and 15.58–16.64% of the microbial community on AC anodes in CW–MFCs, respectively.

Liangyue Cheng, Limin Jiang, Xiaowen Yang et al.

AMB Express • 2024

Microbial fuel cells (MFCs) have the functions of wastewater treatment and power generation. The incorporation of modified anodes enhances the sustainable power generation performance of MFCs. In this study, to evaluate the feasibility of sodium alginate (SA) as a biocompatible binder, hydrogel mixed with super activated carbon (SAC) and SA was modified the carbon cloth anode of MFC. The results showed that the maximum output voltage in the SAC/SA hydrogel modified anode MFC was 0.028 V, which was increased by 115%, compared with the blank carbon cloth anode. The internal resistance of MFC was 9429 Ω, which was 18% lower than that of control (11560 Ω). The maximum power density was 6.14 mW/m^2, which was increased by 365% compared to the control. After modification of SAC/SA hydrogel, the chemical oxygen demand (COD) removal efficiency reached to 56.36% and was 12.72% higher than the control. Coulombic efficiency with modified anode MFC reached 17.65%, which was increased by 104%, compared with the control. Our findings demonstrate the feasibility of utilizing SA as a biocompatible binder for anode modification, thereby imparting sustainable and enhanced power generation performance to MFCs. This study presented a new selectivity for harnessing algal bioresources and improving anode binders in future MFC applications.

Sarah M. Glaven

Microbial Biotechnology • 2019

Microbial electrochemical technologies (METs) are applications or processes that utilize the electrochemical interaction of microbes and electrodes (Schroder et al., 2015). It has been known for over 100 years (Potter, 1911) that microorganisms can form electrical connections to devices, but only recently (approximately 20 years) has this concept been put to technological use. Microbial electrochemistry and electromicrobiology have grown as disciplines due to an intense interest in the possibility of using MET for alternative energy, wastewater treatment and biofuels production. METs have the potential to contribute to a circular economy, where carbon is cycled back into products or electricity from renewable sources. For these reasons, MET represent a significant and attractive source of new enterprise and employment creation. The natural physiological activity of electroactive bacteria, those capable of extracellular electron transfer (EET), has been studied intensely over the past two decades in order to improve efficiency and productivity of METs. A diverse group of scientists has contributed to this knowledge base including microbiologists, electrochemists, physicists, biochemists and molecular biologists. Genetic engineering has been used to determine the molecular underpinnings responsible for carrying charge between cells and the electrode of the two model EET organisms, Geobacter sulfurreducens and Shewanella oneidensis. New electroactive organisms have been discovered using genomics (Eddie et al., 2016), and new ways to transform electrode-associated microbial communities are being developed. Electrochemistry, advanced imaging techniques and modelling have all been employed to track the movement of electrons through biofilms and purified proteins. New lexicons have been created to allow interdisciplinary discussions of extracellular electron transfer, and an entire Center for Electromicrobiology has been funded at Aarhus University in Denmark. Our growing knowledge of the principles of EET is now poised to intersect with the nascent field of synthetic biology to bring about the next generation of MET for power and energy, microbial electrosynthesis and microbial bioelectronics. Synthetic biology is an emerging field that has grown out of the principles of biology and engineering disciplines, devoted to the rational design and engineering of organisms and their components (Church et al., 2014). It is now possible to both engineer specific functions into living systems and construct entirely new ones (Liu et al., 2018a,2018b). Microorganisms are viewed as tiny supercomputers that can be programmed as such by reading, writing and editing the cell’s DNA. Genetic circuits can be designed computationally to wire cells for on-demand functionality (Nielsen et al., 2016), and these circuits can be printed and shipped to a scientist at the bench to deploy in the organism of their choice (Libby and Silver, 2019). Growth of the field of synthetic biology has resulted in the development of new tools and approaches in molecular genetics to advance biotechnology across a wide application space. For example, it is now possible to precisely tune gene expression from 12 independent small-molecule sensors engineered into the genome of E. coli (Meyer et al., 2018) or confer the ability of a bacterial cell to ‘see’ different wavelengths of light and respond in a pre-programmed manner (Fernandez-Rodriguez et al., 2017). Synthetic biology has the potential to advance microbial electrochemical technologies (MET) by bringing new design platforms to engineer EET pathways in organisms that do not naturally have them, modify microbial metabolism to improve EET rates and increase the diversity of products from microbial electrosynthesis. Two examples are given below: (i) enhanced power output from microbial fuel cells and (ii) the potential for microbial electrosynthesis to be a viable approach for fuels or molecules production.

Aishwarya Rani, Suraj Negi, Yu-Ning Chen et al.

GCB Bioenergy • 2025

Biogas, a renewable energy source produced from the anaerobic digestion of biomass and/or organic residues, contains a mixture of methane (CH4) and carbon dioxide (CO2). To be used as a fuel, biogas must be upgraded to increase its CH4 content to over 90%. Traditional upgrading methods, such as amine scrubbing and membrane separation, are energy‐intensive, costly, and environmentally burdensome. This study explores the potential of electrochemical technologies as sustainable alternatives for biogas upgrading from the aspects of energy, environment, economics, and engineering. Recent advances in promising electrochemical approaches including pretreatment, microbial conversion enhancement, CO2 capture, CO2 reduction reactions, and methanation are first reviewed. The performance of these approaches is then systematically compared based on operational characteristics and efficiency metrics. Our findings indicate that microbial and bioelectrochemical systems can achieve CH4 purities over 92%. Also, electrochemical technologies offer > 99.9% hydrogen sulfide removal (desulfurization). State‐of‐the‐art electrochemical CO2 reduction technologies demonstrate Faradaic efficiencies generally 50%–80%, with the selectivity of CH4 up to 99.7%. From the environmental aspect, integrating renewable electricity into microbial, electrochemical (or ‐based), and bioelectrochemical upgrading systems yields roughly 10%–74% life‐cycle GHG reductions relative to conventional fossil‐energy pathways, with certain renewable power‐to‐methane configurations achieving net‐negative emissions. Lastly, this study identifies several priority research directions, such as (1) advanced catalyst and electrode development, (2) system integrations with air pollutant control facilities, (3) life‐cycle environmental and techno‐economic assessment, and (4) digestate valorization for multiple product ecosystems. Electrochemical approaches offer a promising path toward clean, efficient, and decentralized biogas utilization, contributing to global decarbonization and energy transition goals toward a circular bioeconomy.

Anuj Sharma, Aman Grewal, Shubham Kumar Patial et al.

Current Natural Sciences and Engineering • 2025

Bioelectrochemical systems (BES) utilize microbes for energy generation, which means microbes that are known to be harmful can still be non-harmful for their capability to produce alternate energy sources, thus giving dual benefits: waste reduction with simultaneous energy generation. However, the performance of these systems depends on the electrode material, which controls the electrode’s extracellular electron transfer and electron retrieval mechanism. Different materials have been tested as electrode materials to maximize energy efficiency. Recently, carbon-based nanomaterials like graphene sheets, carbon nano-tubes/wires, and quantum dots have been employed successfully as cathode and anode electrodes. These nanomaterials are environment-friendly, non-toxic, and have high physical/chemical stability. This review is an attempt to provide a comprehensive summary of different carbon-based nanomaterials used as electrode modifier materials for BES systems covering the dimensionality of the functional materials (0-D, 1-D, and 2-D), synthesis of materials, carbon composite materials, and (iv) their application in microbial/bio photovoltaic fuel cells (electro/photocatalysis). This review article will also discuss various electrode materials generally used in BESs. There is a surge in the use of carbon-based materials and the opting for low-cost optimised electrodes over expensive, efficient ones. After that, a discussion will be made on the researched nanomaterial approach, their use as advanced working electrode material, with respect to their dimensionality, and the reported power generated by incorporating these materials as electrodes. Then, a detailed discussion will be made on the composite structures that have been reported as more efficient electrode materials than conventional and metal-based electrodes. The coming section briefly explains the design and working principle of MFCs.

Jinsong Du, Jiyu Xin, Menghua Liu et al.

Frontiers in Microbiology • 2022

Roseiflexus castenholzii is an ancient green non-sulfur bacteria that absorbs the solar energy through bacteriochlorophylls (BChls) bound in the only light harvesting (LH) complex, and transfers to the reaction center (RC), wherein primary charge separation occurs and transforms the energy into electrochemical potentials. In contrast to purple bacteria, R. castenholzii RC-LH (rcRC-LH) does not contain an H subunit. Instead, a tightly bound tetraheme cytochrome c subunit is exposed on the P-side of the RC, which contains three BChls, three bacteriopheophytins (BPheos), two menaquinones, and one iron for electron transfer. These novel structural features of the rcRC-LH are advantageous for enhancing the electron transfer efficiency and subsequent photo-oxidation of the c-type hemes. However, the photochemical properties of rcRC-LH and its applications in developing the photo-bioelectrochemical cells (PBECs) have not been characterized. Here, we prepared a PBEC using overlapped fluorine-doped tin oxide (FTO) glass and Pt-coated glass as electrodes, and rcRC-LH mixed with varying mediators as the electrolyte. Absence of the H subunit allows rcRC-LH to be selectively adhered onto the hydrophilic surface of the front electrode with its Q-side. Upon illumination, the photogenerated electrons directly enter the front electrode and transfer to the counter electrode, wherein the accepted electrons pass through the exposed c-type hemes to reduce the excited P+, generating a steady-state current of up to 320 nA/cm2 when using 1-Methoxy-5-methylphenazinium methyl sulfate (PMS) as mediator. This study demonstrated the novel photoelectric properties of rcRC-LH and its advantages in preparing effective PBECs, showcasing a potential of this complex in developing new type PBECs.

K. Cheng, A. Kaksonen, R. Cord-Ruwisch

Environmental Technology • 2022

Bioelectrochemical systems (BES) are emerging environmental biotechnology for recovering ammonia from waste streams. It has been tested extensively for treating ammonium-rich wastewater. This study examined the suitability of BES to facilitate carbon removal and ammonium extraction from a low ammonium liquor (3.7 mM) that mimics municipal wastewater, and concomitant production of high-purity hydrogen gas, which could potentially be harnessed as a fuel or internally recycled for ammonia stripping. Results showed that a two-chamber cation exchange membrane-equipped BES enabled a high hydrogen yield (22.8 m3 H2 m-3 d-1; >98% cathodic efficiency) and chemical oxygen demand (COD) removal (80%; 2.43 kg COD m-3d-1 at a hydraulic retention time of 4.4 h). However, for the treatment of wastewater the system demanded high energy (2.3 kWh kg COD-1; 152 kWh kg-1 N removed) and base for pH adjustment. The technology may be more suitable for recovering ammonium from wastewaters with molar ammonium to BOD ratio closer to the desired stoichiometric ratio of four, and for waste streams containing sufficient alkalinity or pH-buffering capacity, eliminating the need for dosing cation-bearing alkali.

Cong-Long Nguyen, B. Tartakovsky, L. Woodward

ACS Omega • 2019

Direct electricity production from waste biomass in a microbial fuel cell (MFC) offers the advantage of producing renewable electricity at a high Coulombic efficiency. However, low MFC voltage (below 0.5 V) necessitates the simultaneous operation of multiple MFCs controlled by a power management system (PMS) adapted for operating bioelectrochemical systems with complex nonlinear dynamics. This work describes a novel PMS designed for efficient energy harvesting from multiple MFCs. The PMS includes a switched-capacitor-based converter, which ensures operation of each MFC at its maximum power point (MPP) by regulating the output voltage around half of its open-circuit voltage. The open-circuit voltage of each MFC is estimated online regardless of MFC internal parameter knowledge. The switched-capacitor-based converter is followed by an upconverter, which increases the output voltage to a required level. Advantages of the proposed PMS include online MPP tracking for each MFC and high (up to 85%) power conversion efficiency. Also, the PMS prevents voltage reversal by disconnecting an MFC from the circuit whenever its voltage drops below a predefined threshold. The effectiveness of the proposed PMS is verified through simulations and experimental runs.

María Teresa Pines Pozo, Ester Lopez Fernandez, José Villaseñor et al.

Applied Sciences • 2025

The rapid technological advancements and the shift towards clean energy have significantly increased the demand for metals, leading to an increasing metal pollution problem. This review explores recent advances in bioelectrochemical systems (BES) for metal recovery from waste, especially Acid Mine Drainage (AMD) and Electrical, Electronic Wastes (EEW) and waste from smelters, highlighting their potential as a sustainable and economically viable alternative to traditional methods. This study addresses the applications and limitations of current BES recovery techniques. BES, including microbial fuel cells (MFCs), microbial electrolytic cells (MECs), and Microbial Desalination Cells (MDCs), offer promising solutions by combining microbial processes with electrochemical reactions to recover valuable metals while reducing energy requirements. This review categorizes recent research into two main areas: pure BES applications and BES coupled with other technologies. Key findings include the efficiency of BES in recovering metals like copper, chromium, vanadium, iron, zinc, nickel, lead, silver, and gold and the potential for integrating BES with other systems to enhance performance. Despite significant progress in BES application for metal recovery, challenges such as high costs and slow kinetics remain, necessitating further research to optimize materials, configurations, and operational conditions. The work also includes an economic assessment and guidelines for BES development and upscale. This review underscores the critical role of BES in advancing sustainable metal recovery and mitigating the environmental impact of metal pollution.

Nishat Khan, M. Danish Khan, A. Nizami et al.

RSC Advances • 2018

Bio-electrochemical degradation of pentachlorophenol was carried out in single as well as dual chambered microbial fuel cell (MFC) with simultaneous production of electricity. The maximum cell potential was recorded to be 787 and 1021 mV in single and dual chambered systems respectively. The results presented nearly 66 and 89% COD removal in single and dual chambered systems with corresponding power densities of 872.7 and 1468.85 mW m−2 respectively. The highest coulombic efficiency for single and dual chambered counterparts was found to be 33.9% and 58.55%. GC-MS data revealed that pentachlorophenol was more effectively degraded under aerobic conditions in dual-chambered MFC. Real-time polymerase chain reaction showed the dominance of exoelectrogenic Geobacter in the two reactor systems with a slightly higher concentration in the dual-chambered system. The findings of this work suggested that the aerobic treatment of pentachlorophenol in cathodic compartment of dual chambered MFC is better than its anaerobic treatment in single chambered MFC in terms of chemical oxygen demand (COD) removal and output power density.

E. Labelle, H. May

Frontiers in Microbiology • 2017

It was hypothesized that a lack of acetogenic biomass (biocatalyst) at the cathode of a microbial electrosynthesis system, due to electron and nutrient limitations, has prevented further improvement in acetate productivity and efficiency. In order to increase the biomass at the cathode and thereby performance, a bioelectrochemical system with this acetogenic community was operated under galvanostatic control and continuous media flow through a reticulated vitreous carbon (RVC) foam cathode. The combination of galvanostatic control and the high surface area cathode reduced the electron limitation and the continuous flow overcame the nutrient limitation while avoiding the accumulation of products and potential inhibitors. These conditions were set with the intention of operating the biocathode through the production of H2. Biofilm growth occurred on and within the unmodified RVC foam regardless of vigorous H2 generation on the cathode surface. A maximum volumetric rate or space time yield for acetate production of 0.78 g/Lcatholyte/h was achieved with 8 A/Lcatholyte (83.3 A/m2projected surface area of cathode) supplied to the continuous flow/culture bioelectrochemical reactors. The total Coulombic efficiency in H2 and acetate ranged from approximately 80–100%, with a maximum of 35% in acetate. The overall energy efficiency ranged from approximately 35–42% with a maximum to acetate of 12%.

Lianbin Cao, Hongmei Sun, Yamei Ma et al.

Microbial Cell Factories • 2023

The strain Lsc-8 can produce a current density of 33.08 µA cm^−2 using carboxymethylcellulose (CMC) as a carbon source in a three-electrode configuration. A co-culture system of strain Lsc-8 and Geobacter sulfurreducens PCA was used to efficiently convert cellulose into electricity to improve the electricity generation capability of microbial fuel cells (MFCs). The maximum current density achieved by the co-culture with CMC was 559 μA cm^−2, which was much higher than that of strain Lsc-8 using CMC as the carbon source. The maximum power density reached 492.05 ± 52.63 mW cm^−2, which is much higher than that previously reported. Interaction mechanism studies showed that strain Lsc-8 had the ability to secrete riboflavin and convert cellulose into acetic acid, which might be the reason for the high electrical production performance of the co-culture system. In addition, to the best of our knowledge, a co-culture or single bacteria system using agricultural straw as the carbon source to generate electricity has not been reported. In this study, the maximum current density of the three-electrode system inoculated with strain Lsc-8 was 14.56 μA cm^−2 with raw corn stover as the sole carbon source. Raw corn stover as a carbon source was also investigated for use in a co-culture system. The maximum current density achieved by the co-culture was 592 μA cm^−2. The co-culture system showed a similar electricity generation capability when using raw corn stover and when using CMC. This research shows for the first time that a co-culture or single bacteria system can realize both waste biomass treatment and waste power generation.

Jung-Chen Wu, Wei‐Mon Yan, Chin‐Tsan Wang et al.

Energies • 2018

Due to the fact that Iron oxide (Fe2O3) is known to have a good effect on the photochemical reaction of catalysts, an investigation in this study into the enhancement of the degradation performance of bio-electro-Fenton microbial fuel cells (Bio-E-Fenton MFCs) was carried out using three photocatalytic cathodes. These cathodes were produced at different calcination temperatures of Fe2O3 ranging from 500 °C to 900 °C for realizing their performance as photo catalysts within the cathodic chamber of an MFC, and they were compared for their ability to degrade oily wastewater. Results show that a suitable temperature for the calcination of iron oxide would have a significantly positive effect on the performance of Bio-E-Fenton MFCs. An optimal calcination temperature of 500 °C for Fe2O3 in the electrode material of the cathode was observed to produce a maximum power density of 52.5 mW/m2 and a chemical oxygen demand (COD) degradation rate of oily wastewater (catholyte) of 99.3% within one hour of operation. These novel findings will be useful for the improvement of the performance and applications of Bio-E-Fenton MFCs and their future applications in the field of wastewater treatment.

G. M. Aleid, Anoud Saud Alshammari, Asma D. Alomari et al.

Processes • 2023

One of the most advanced systems of microbial fuel cells is the benthic microbial fuel cell (BMFC). Despite several developments, this strategy still has a number of significant flaws, such as instable organic substrate. Waste material (sugarcane) is used as a substrate in this work to address the organic substrate instability. The process was operated continuously for 70 days. A level of 300 mV was achieved after 33 days of operation, while the degradation efficiencies of Pb (II), Cd (II), and Cr (III) were more than 90%. More than 90% of the removed chemical oxygen demand (COD) was also recorded. The measured power density was 3.571 mW/m2 at 1000 external resistance with 458 internal resistance. This demonstrates that electrons are effectively transported throughout the operation. The Bacillus strains are the most dominant bacterial community on the surface of the anode. This research’s mechanism, which involves metal ion degradation, is also explained. Finally, parameter optimization indicated that pH 7 works efficiently. In addition to that, there are some future perspectives and concluding remarks enclosed.

Hailiang Song, Shuai Zhang, Xizi Long et al.

Water • 2017

Constructed wetland-coupled microbial fuel cell systems (CW-MFCs) incorporate an aerobic zone and an anaerobic zone to generate electricity that achieves the oxidative degradation of contaminants. However, there are few reports on the performance of such coupled systems. In this study, we determined the optimal configuration of CW-MFCs to characterize their electricity generation performance. Based on the results using different levels of dissolved oxygen among the CW-MFCs, we concluded that a 20-cm distance between the anode and cathode produced an optimal removal of chemical oxygen demand (COD) of 94.90% with a 0.15 W/m3 power density, 339.80 Ω internal resistance, and 0.31% coulombic efficiency. In addition, a COD of 200 mg/L provided greater electricity generation (741 mV open circuit voltage, 0.20 W/m3 power density, 339.80 Ω internal resistance, and 0.49 mA current) and purification ability (90.45% COD removal) to meet system COD loading limitations than did higher COD values. By adding 50 mM phosphate buffer solution to synthetic wastewater, relatively high conductivity and buffer capacity were achieved, resulting in improvement in electricity generation. These findings highlight important aspects of bioelectricity generation in CW-MFCs.

Chia-Chieh Hsu, Yi-Chu Lin, Yaobao Lin et al.

Advanced Energy and Sustainability Research • 2021

Microbial fuel cells (MFCs), which convert chemical energy into electricity using microbes, are an emerging sustainable energy technology. However, high costs and low power output limit the advanced development of MFCs. This study utilizes the agricultural waste, Trapa natans husks, to obtain low‐cost nanoporous carbons. The Trapa natans husk‐derived nanoporous carbons (TNHs) are used as electrode materials in Escherichia coli system‐based MFCs. After optimization of both anode and cathode materials for MFCs, a high average power density of 5713 mW m−2 is achieved, which is 1.9 times greater than that of commercial activated carbon. It is shown that TNHs have better bacterial adhesion and electrochemical activities owing to their favorable pore size distribution, suitable functional group, high surface area, and excellent biocompatibility and conductivity. Furthermore, the supercapacitors (SCs) with TNH‐based electrodes are utilized to store the energy generated from MFCs. The SC with TNH‐600 electrodes exhibits a high specific capacitance of 84 F g−1 at a current density of 1 A g−1 after 1000 cycles. This study demonstrates that TNH is a promising electrode material for biofriendly and renewable MFCs, and the MFC‐SC system with TNH electrodes is a high‐power sustainable energy generation and storage device.

Yanhua Wang, Jiayan Wu, Shengke Yang et al.

International Journal of Environmental Research and Public Health • 2018

Due to the known problems of microbial fuel cells (MFCs), such as low electricity generation performance and high cost of operation, we modified the electrode with graphene and polyaniline (PANI) is a single-chamber air-cathode MFC and then evaluated the effects of electrode modification on MFC electricity generation performance. Carbon cloth electrodes (unmodified, CC; graphene-modified, G/CC; and polyaniline-graphene-modified, PANI-G/CC) were prepared using the impregnation method. Sulfonated cobalt phthalocyanine (CoPcS) was then introduced as a cathode catalyst. The Co-PANI-G/CC cathode showed higher catalytic activity toward oxygen reduction compared with other electrodes. The maximum power density of the MFC with Co-PANI-G/CC cathode was 32.2 mW/m2, which was 1.8 and 6.1 times higher than the value obtained with Co-G/CC and Co/CC cathodes, respectively. This indicates a significant improvement in the electricity generation of single-chamber MFCs and provides a simple, effective cathode modification method. Furthermore, we constructed single-chamber MFCs using the modified anode and cathode and analyzed electricity generation and oxytetracycline (OTC) degradation with different concentrations of OTC as the fuel. With increasing added OTC concentration, the MFC performance in both electricity generation and OTC degradation gradually decreased. However, when less than 50 mg/L OTC was added, the 5-day degradation rate of OTC reached more than 90%. It is thus feasible to process OTC-containing wastewater and produce electricity using single-chamber MFCs, which provides a new concept for wastewater treatment.