Search Results (35)

Microbial Electrochemistry Technology (MET) leverages the unique process of extracellular electron transfer (EET) between electroactive bacteria (EAB) and electrodes to enable various applications, such as electricity generation, bioremediation, and wastewater treatment. This review highlights significant advancements in EET mechanisms, emphasizing both outward and inward electron transfer pathways mediated by diverse electroactive microorganisms. Notably, the role of electron shuttles, genetic modifications, and innovative electrode materials are discussed as strategies to enhance EET efficiency. Recent studies illustrate the importance of redox-active molecules, such as flavins and metal nanoparticles, in facilitating electron transfer, while genetic engineering has proven effective in optimizing microbial physiology to boost EET rates. The review also examines the impact of electrode materials on microbial attachment and performance, showcasing new composites and nanostructures that enhance power output in microbial fuel cells. By synthesizing the recent findings and proposing emerging research directions, this work provides an overview of EET enhancement strategies, aiming to inform future technological innovations in bioelectrochemical systems (BESs). Full article

Bioelectrochemical systems (BESs) are devices capable of converting chemical energy into electrical energy using microorganisms as catalysts. These systems have been extensively studied at the laboratory level, but, due to multiple difficulties, their large-scale implementation has been explored only sparingly. This study presents the most recent technological advances for scaling up BESs. In the same way, the main technical and economic challenges that hinder the correct implementation of these systems at a large scale are mentioned. The study concludes with a review of successful case studies in scaling up BESs and discusses future directions and emerging trends. Full article

Optimal product synthesis in bioelectrochemical systems (BESs) requires a comprehensive understanding of the relationship between external voltage and microbial yield. While most studies assume constant growth yields or rely on empirical estimates, this study presents a novel thermodynamic model, linking anodic oxidation and cathodic carbon dioxide (${CO}_2$) reduction to methane (${CH}_4$) by growing microbial biofilm. Through integrating theoretical Gibbs free energy calculations, the model predicts electron and proton transfers for autotrophic methanogen and anode-respiring bacteria (ARB) growth, accounting for varying applied voltages and substrate concentrations. The findings identify an optimal applied cathodic potential of −0.3 V vs. the standard hydrogen electrode (SHE) for maximizing ${CH}_4$ production under standard conditions (pH 7, 25 °C, 1 atm) regardless of ohmic losses. The model bridges the stoichiometry of anodic and cathodic biofilms, addressing research gaps in simulating anodic and cathodic biofilm growth simultaneously. Additionally, sensitivity analyses reveal that lower substrate concentrations require more negative voltages than standard condition to stimulate microbial growth. The model was validated using experimental data, demonstrating reasonable predictions of biomass growth and ${CH}_4$ yield under different operating voltages in a multi substrate system. The results show that higher voltage inputs increase biomass yield while reducing ${CH}_4$ output due to non-optimal voltage. This validated model provides a tool for optimizing BES performance to enhance ${CH}_4$ recovery and biofilm stability. These insights contribute to finding optimum voltage for the highest ${CH}_4$ production for energy efficient ${CO}_2$ reduction for scaling up BES technology. Full article

Because of their high persistence, polycyclic aromatic hydrocarbons (PAHs) are found in a wide range of settings and pose a health risk to both humans and other organisms. Degradation of PAHs is an essential part of environmental management. By combining biological metabolism and electrochemical processes, bioelectrochemical systems (BESs) can degrade PAHs and provide important applications by converting the chemical energy of pollutants into electrical energy for energy conversion and recovery. This review provides a comprehensive introduction to PAH degradation by BESs, including PAH sources, degradation effects of BESs, performance enhancement methods, degradation pathways, and dominant microorganisms. By focusing on the relevant research in recent years, the main innovative research focuses on the optimization of the configuration, the electrode preparation, and the media additions to improve the removal performance of PAHs. It demonstrates the potential of BESs in the field of environmental remediation, especially their effectiveness in treating difficult-to-degrade pollutants such as PAHs, by concentrating on the application and mechanism of BESs in PAH degradation. This review is intended to provide the inexperienced reader with an insight into this research area and to point out directions for future research, especially in the design optimization of BESs and microbial community analysis. Full article

Despite over two decades of intense research into bioelectrochemical systems (BESs), their practical implementation remains unrealized, partly due to the low performance of bioelectrodes. With the introduction of additive manufacturing techniques, the development of a new generation of bioelectrodes with custom-shaped geometries using conductive composites has become feasible. This study examines the potential of using two conductive composites, Poly-lactic acid (PLA) and thermoplastic polyurethane (TPU), for 3D-printed electrodes. Electrochemical characterization reveals that TPU has a charge transfer resistance approximately two orders of magnitude higher than PLA, rendering it unsuitable for bioelectrodes. The presence of triangular patterns enhances the performance of planar electrodes, with optimal results observed for PLA-based electrodes with surface pattern depths between 0.6 and 1.4 mm. Additionally, electrodeposition (ED) of graphene oxide (GO) further improves performance across all cases. During the subsequent biotic start-up, patterned PLA electrodes with a depth of 1.4 mm exhibit higher current. However, these 3D-printed electrodes exhibit degradation after 56 days of operation. Full article

Studies have used anaerobic-digester sludge and/or effluent as inocula for bioelectrochemical systems (BESs), such as microbial fuel cells (MFCs), for power generation, while limited studies have isolated and characterized electrochemically active bacteria (EAB) that inhabit anaerobic digesters. In the present work, single-chamber MFCs were operated using the anaerobic-digester effluent as the sole source of organics and microbes, and attempts were made to isolate EAB from anode biofilms in MFCs by repeated anaerobic cultivations on agar plates. Red colonies were selected from those grown on the agar plates, resulting in the isolation of three phylogenetically diverse strains affiliated with the phyla Bacillota, Campylobacterota and Deferribacterota. All these strains are capable of current generation in pure-culture BESs, while they exhibit different electrochemical properties as assessed by cyclic voltammetry. The analyses of their cell-free extracts show that cytochromes are abundantly present in their cells, suggesting their involvement in current generation. The results suggest that anaerobic digesters harbor diverse EAB, and it would be of interest to examine their ecological niches in anaerobic digestion. Full article

Bioelectrochemical systems (BESs) are an innovative technology for the efficient degradation of antibiotics. Shewanella oneidensis (S. oneidensis) MR-1 plays a pivotal role in degrading sulfamethoxazole (SMX) in BESs. Our study investigated the effect of BES conditions on SMX degradation, focusing on microbial activity. The results revealed that BESs operating with a 0.05 M electrolyte concentration and 2 mA/cm² current density outperformed electrolysis cells (ECs). Additionally, higher electrolyte concentrations and elevated current density reduced SMX degradation efficiency. The presence of nutrients had minimal effect on the growth of S. oneidensis MR-1 in BESs; it indicates that S. oneidensis MR-1 can degrade SMX without nutrients in a short period of time. We also highlighted the significance of mass transfer between the cathode and anode. Limiting mass transfer at a 10 cm electrode distance enhanced S. oneidensis MR-1 activity and BES performance. In summary, this study reveals the complex interaction of factors affecting the efficiency of BES degradation of antibiotics and provides support for environmental pollution control. Full article

Extracellular electron transfer (EET) is a biological mechanism that plays a crucial role in various bioelectrochemical systems (BESs) and has substantial implications for renewable energy production. By utilizing the metabolic capacities of exoelectrogens, BESs offer a viable and environmentally friendly approach to electricity generation and chemical production; however, the diminished effectiveness of EET remains a hindrance to their optimal application in practical contexts. This paper examines the various strategies that have the potential to be employed to enhance the efficiency of EET systems and explores the potential for the integration of BESs technology with contemporary technologies, resulting in the development of an enhanced and sustainable system. It also examines how quorum sensing, electrode modifications, electron shuttles, and mediators can aid in improving EET performance. Many technological innovations, such as additive manufacturing, the science of nanotechnology, the technique of genetic engineering, computational intelligence, and other combinations of technologies that can be used to augment the efficacy of BESs are also discussed. Our findings will help readers understand how BESs, though an evolving technology, can play an important role in addressing our environmental concerns. Technical constraints are identified, and future directions in the field of EET are suggested. Full article

This research sought to enhance the efficiency and biocompatibility of anodes in bioelectrochemical systems (BESs) such as microbial fuel cells (MFCs), with an aim toward large-scale, real-world applications. The study focused on the effects of acid-heat treatment and chemical modification of three-dimensional porous pristine carbon felt (CF) on power generation. Different treatments were applied to the pristine CF, including coating with carbon nanofibers (CNFs) dispersed using dodecylbenzene sulfonate (SDBS) surfactant and biopolymer chitosan (CS). These processes were expected to improve the hydrophilicity, reduce the internal resistance, and increase the electrochemically active surface area of CF anodes. A high-resolution scanning electron microscopy (HR-SEM) analysis confirmed successful CNF coating. An electrochemical analysis showed improved conductivity and charge transfer toward [Fe(CN)6]^3−/4− redox probe with treated anodes. When used in an air cathode single-chamber MFC system, the untreated CF facilitated quicker electroactive biofilm growth and reached a maximum power output density of 3.4 W m⁻², with an open-circuit potential of 550 mV. Despite a reduction in charge transfer resistance (R_ct) with the treated CF anodes, the power densities remained unchanged. These results suggest that untreated CF anodes could be most promising for enhancing power output in BESs, offering a cost-effective solution for large-scale MFC applications. Full article

The over-exploitation of fossil fuels and their negative environmental impacts have attracted the attention of researchers worldwide, and efforts have been made to propose alternatives for the production of sustainable and clean energy. One proposed alternative is the implementation of bioelectrochemical systems (BESs), such as microbial fuel cells (MFCs), which are sustainable and environmentally friendly. MFCs are devices that use bacterial activity to break down organic matter while generating sustainable electricity. Furthermore, MFCs can produce bioelectricity from various substrates, including domestic wastewater (DWW), municipal wastewater (MWW), and potato and fruit wastes, reducing environmental contamination and decreasing energy consumption and treatment costs. This review focuses on recent advancements regarding the design, configuration, and operation mode of MFCs, as well as their capacity to produce bioelectricity (e.g., 2203 mW/m²) and fuels (i.e., H₂: 438.7 mg/L and CH₄: 358.7 mg/L). Furthermore, this review highlights practical applications, challenges, and the life-cycle assessment (LCA) of MFCs. Despite the promising biotechnological development of MFCs, great efforts should be made to implement them in a real-time and commercially viable manner. Full article

Bioelectrochemical systems (BESs), rather than physicochemical processes, are used for wastewater remediation, electricity production, and zero carbon dioxide emission. Textile effluents contain organic and inorganic compounds that can fuel BESs. The main goal of this study was to understand the interplay between the anode material, its surface area, the potential applied to the working electrode (WE), and the concentration of the co-substrate, and how these factors lead to the formation of highly efficient thermohalophilic bioanodes (THB) retrieved from Chott El Djerid (SCD) hypersaline sediment for the treatment of synthetic textile wastewater. To this end, twenty-seven bioanode formation experiments were designed using a Box-Behnken matrix and response surface methodology to understand concomitant interactions. All experiments were conducted in electrochemical reactors of final volume 750 mL inoculated with 80% of enrichment medium containing three azo dyes at a concentration of 300 ppm and 20% of biocatalyst microbial SCD source, at 45 °C. The optimal levels were predicted using NemrodW software as carbon felt (CF) anode material, 6 cm² anode surface, 7 g/L glucose concentration, and −0.1 V applied potential. These theoretical results were experimentally validated, using maximum current output of 5.23 ± 0.30 A/m², decolorization rate of 100%, and a chemical oxygen demand (COD) removal rate of 96 ± 1%. Illumina Miseq results revealed that bacterial community harbored the bioanode was dominated at phylum level by Firmicutes (67.1%). At the species level, the biofilm was mainly colonized by Orenia metallireducens species (59.5%). Obtained findings show a promising application of THB in the degradation of recalcitrant molecules as well as for the energy recovery. Full article

Bioelectrochemical systems (BESs) are an emerging technology for wastewater treatment and resource recovery. These systems facilitate electron transfer between microorganisms and electrodes, enabling their application in various fields, such as electricity production, bioremediation, biosensors, and biocatalysis. However, electrode biofilms, which play a critical role in BESs, face several challenges (e.g., a long acclimation period, low attached biomass, high electron transfer resistance, and poor tolerance and stability) that limit the development of this technology. Quorum sensing (QS) is a communication method among microorganisms that can enhance the performance of BESs by regulating electrode biofilms. QS regulation can positively impact electrode biofilms by enhancing extracellular electron transfer (EET), biofilm formation, cellular activity, the secretion of extracellular polymeric substances (EPS), and the construction of microbial community. In this paper, the characteristics of anode electrogenic biofilms and cathode electrotrophic biofilms in BESs, EET mechanisms, and the main factors affecting biofilm formation were summarized. Additionally, QS regulation mechanisms for biofilm formation, strategies for enhancing and inhibiting QS, and the application of QS regulation for electrode biofilms in BESs were systematically reviewed and discussed. This paper provides valuable background information and insights for future research and development of BES platforms based on QS regulation of electrode biofilms. Full article

Bioelectrochemical systems (BESs) have great potential in renewable energy production technologies. BES can generate electricity via Microbial Fuel Cell (MFC) or use electric current to synthesize valuable commodities in Microbial Electrolysis Cells (MECs). Various reactor configurations and operational protocols are increasing rapidly, although industrial-scale operation still faces difficulties. This article reviews the recent BES related to literature, with special attention to electrosynthesis and the most promising reactor configurations. We also attempted to clarify the numerous definitions proposed for BESs. The main components of BES are highlighted. Although the comparison of the various fermentation systems is, we collected useful and generally applicable operational parameters to be used for comparative studies. A brief overview links the appropriate microbes to the optimal reactor design. Full article

The need for greener processes to satisfy the demand of platform chemicals together with the possibility of reusing CO₂ from human activities has recently encouraged research on the set-up, optimization, and development of bioelectrochemical systems (BESs) for the electrosynthesis of organic compounds from inorganic carbon (CO₂, HCO₃⁻). In the present study, we tested the ability of Clostridium saccharoperbutylacetonicum N1-4 (DSMZ 14923) to produce acetate and D-3-hydroxybutyrate from inorganic carbon present in a CO₂:N₂ gas mix. At the same time, we tested the ability of a Shewanella oneidensis MR1 and Pseudomonas aeruginosa PA1430/CO1 consortium to provide reducing power to sustain carbon assimilation at the cathode. We tested the performance of three different systems with the same layouts, inocula, and media, but with the application of 1.5 V external voltage, of a 1000 Ω external load, and without any connection between the electrodes or external devices (open circuit voltage, OCV). We compared both CO₂ assimilation rate and production of metabolites (formate, acetate 3-D-hydroxybutyrate) in our BESs with the values obtained in non-electrogenic control cultures and estimated the energy used by our BESs to assimilate 1 mol of CO₂. Our results showed that C. saccharoperbutylacetonicum NT-1 achieved the maximum CO₂ assimilation (95.5%) when the microbial fuel cells (MFCs) were connected to the 1000 Ω external resistor, with the Shewanella/Pseudomonas consortium as the only source of electrons. Furthermore, we detected a shift in the metabolism of C. saccharoperbutylacetonicum NT-1 because of its prolonged activity in BESs. Our results open new perspectives for the utilization of BESs in carbon capture and electrosynthesis of platform chemicals. Full article

Bioelectrochemical systems (BESs) have emerged as a technology that is able to recover resources from different kinds of substrates, especially wastewater. Nutrient recovery, mostly based on membrane reactor configuration, is a clear niche for BES application. The recovery of nitrogen or phosphorus allows for treatment of wastewater while simultaneously collecting a concentrated stream with nutrients that can be reintroduced into the system, becoming a circular economy solution. The aim of this study is to review recent advances in membrane-based BESs for nitrogen and phosphorus recovery and compare the recovery efficiencies and energy requirements of each system. Finally, there is a discussion of the main issues that arise from using membrane-based BESs. The results presented in this review show that it would be beneficial to intensify research on BESs to improve recovery efficiencies at the lowest construction cost in order to take the final step towards scaling up and commercialising this technology. Full article