Search Results (223)

Plant Microbial Fuel Cells (PMFCs) represent a promising technology that uses electroactive bacteria to convert the chemical energy in organic matter into electrical energy. The addition of carbon pellet on electrodes may increase the specific surface area for colonization via bacteria. Use of nutrients such as urea could enhance plant growth. Our study aims to address the following questions: (1) Does carbon pellet layering affect the electrical performance of PMFCs? (2) Does urea treatment of the plants used to feed the PMFCs affect the electrical performance? A new prototype of PMFC has been tested: the plant pot is on the top, drainage water percolates to the tub below, containing the Microbial Fuel Cells (MFCs). To evaluate the best layering setup, two groups of MFCs were constructed: a “Double layer” group (with carbon pellet both on the cathode and on the anode), and a “Single layer” group (with graphite only on the cathode). All MFCs were plant-fed by Spathiphyllum lanceifolium L leachate. After one year, each of the previous two sets has been divided into two subsets: one wetted with percolate from plants fertilized with urea, and the other with percolate from unfertilized plants. Open circuit voltage (mV), short circuit peak current, and short circuit current after 5 s (mA) produced values that were measured on a weekly basis. PMFCs characterized by a “Single layer” group performed better than the “Double layer” group most times, in terms of higher and steadier values for voltage and calculated power. Undesirable results regarding urea treatment suggest the use of less concentrated urea solution. The treatment may provide consistency but appears to limit voltage and peak values, particularly in the “Double layer” configuration. Full article

The underutilization of fruit waste in agroindustry—particularly star fruit—leads to leachate generation, emissions, and disposal costs, highlighting the need for circular alternatives that treat organic fractions while producing energy. This study evaluated the bioelectrochemical conversion of carambola (Averrhoa carambola) residues in single-chamber microbial fuel cells (MFCs). Three 1000 mL reactors were constructed using carbon anodes and zinc cathodes, operated for 35 days with continuous voltage recording and daily monitoring of pH, conductivity, and ORP. Polarization curves were obtained, and FTIR and SEM analyses were conducted to characterize substrate transformation and anode colonization. The anodic biofilm was also profiled using metagenomics. Measurements were performed using calibrated electrodes and a data logger with one minute intervals. The systems exhibited rapid startup and reached peak performance on day 22, with a voltage of 1.352 V, current of 3.489 mA, conductivity of 177.90 mS/cm, ORP of 202.01 mV, and pH of 4.89. The V–I curve indicated an internal resistance of 16.51 Ω, and the maximum power density reached 0.517 mW/cm². FTIR revealed a reduction in bands associated with carbohydrates and proteins, consistent with biodegradation, while SEM confirmed extensive biofilm formation and increased anode surface roughness. Metagenomic analysis showed dominance of Acetobacter (59.35%), with Bacteroides (12.93%) and lactobacilli contributing to fermentative and electrogenic synergies. Finally, the series connection of three MFCs generated 2.71 V, sufficient to power an LED, demonstrating the feasibility of low-power applications and the potential for system scalability. Full article

This study investigates microbial fuel cell (MFC) performance through the modification of Saccharomyces cerevisiae with gold nanoparticles (AuNPs) and polypyrrole (PPy). The yeast/AuNP-modified electrodes generated the highest median current of 2.57 nA, significantly outperforming the yeast/PPy-modified (0.82 nA) electrodes. Power density measurements further confirmed the superior performance of the yeast/AuNP-modified electrodes, showcasing a notable improvement in current densities and power outputs. Yeast/AuNP-modified graphite electrodes produced a higher power density of 22.8 mW/m², while exhibiting a lower current density compared to electrodes modified solely with yeast, which achieved a power density of 5.7 mW/m². These findings highlight the potential of AuNPs in significantly enhancing the electrochemical performance of yeast-based MFCs, providing a promising approach for the development of more efficient bioelectrochemical systems. Full article

Microbial fuel cells (MFCs) can have high pollutant removal efficiencies and generate electricity; however, the use of selective membranes represents a considerable expense. In this investigation, the performance of a membraneless MFC was evaluated at different hydraulic retention times (HRTs) of 12, 24, 36, and 48 h. The chemical oxygen demand removal efficiencies (CODREs) were 93.5, 90.9, 87.3, and 85.4%, and the biochemical oxygen demand (BODRE) values were 94.5, 91.5, 88.9, and 85.5 at HRTs of 48, 36, 24, and 12 h, respectively. Lower concentrations of solids (suspended solids and total dissolved solids), total nitrogen, phosphorus, fats and oils, and microbiological contamination (helminth eggs and fecal coliforms) were detected when operating the system at a 48 h HRT. At an HRT of 12 h, no decrease in electrical conductivity was detected, whereas at 48 h, it decreased by 19.6%. The oxidation–reduction potential and OCV increased at longer HRTs. The microorganisms detected at the anode were Achromobacter denitrificans, Achromobacter anxifer, and Pseudomonas aeruginosa. The 48 h HRT improved the chemical, physical, and microbiological quality of the municipal wastewater, favoring voltage generation. Full article

This study introduces an advanced strategy for improving microbial fuel cell (MFC) performance in hexavalent chromium (Cr(VI)) wastewater treatment. A high-performance nano-iron sulfide (nano-FeS) hybridized biocathode was developed by regulating glucose concentration and applying an external voltage. The combination of a glucose concentration of 1000 mg/L and a 0.2 V applied voltage greatly promoted the in situ biosynthesis of nano-FeS, resulting in smaller particle sizes and increased quantities within the biocathode, leading to enhanced electrochemical performance. The MFC with the hybridized biocathode exhibited the highest power density (43.45 ± 1.69 mW/m²) and Cr(VI) removal rate (3.99 ± 0.09 mg/L·h), outperforming the control by 29% and 71%, respectively. The improvements were attributed to the following processes. (1) Nano-FeS provided additional active sites that enhanced electron transfer and electrocatalytic activity, reducing cathode passivation; (2) it protected microorganisms by reducing Cr(VI) toxicity, promoting redox-active substance enrichment and antioxidant enzyme secretion, which maintained microbial activity; (3) the biocathode selectively enriched electroactive and Cr(VI)-reducing bacteria (such as Brucella), fostering a stable and symbiotic microbial community. This study highlights the promising potential of regulating carbon source and external voltage to boost nano-FeS biosynthesis, offering a sustainable and efficient strategy for MFC-based Cr(VI) wastewater treatment with practical implications. Full article

This study systematically compares the environmental and economic performance of three wastewater treatment systems: constructed wetlands (CWs), microbial fuel cells (MFCs), and their integration (CW–MFC). Lab-scale units of each system were constructed using a multi-media matrix (gravel, zeolite, and granular activated carbon), composite native wetland species (Juncus effusus, Iris sp., and Typha angustifolia), carbon-based electrodes (graphite), and standard inoculum for CW and CW–MFC. The MFC system employed carbon-based electrodes and proton-exchange membrane. The experimental design included a parallel operation of all systems treating domestic wastewater under identical hydraulic and organic loading rates. Environmental impacts were quantified across construction and operational phases using life cycle assessment (LCA) with GaBi software 9.2, employing TRACI 2021 and ReCiPe 2016 methods, while techno-economic analysis (TEA) evaluated capital and operational costs. The key results indicate that CW demonstrates the lowest global warming potential (142.26 kg CO₂-eq) due to its reliance on natural biological processes. The integrated CW–MFC system achieved enhanced pollutant removal (82.8%, 87.13%, 78.13%, and 90.3% for COD, NO₃, TN, and TP) and bioenergy generation of 2.68 kWh, balancing environmental benefits with superior treatment efficiency. In contrast, the stand-alone MFC shows higher environmental burdens, primarily due to energy-intensive material requirements and fabrication processes. TEA results highlight CW as the most cost-effective solution (USD 627/m³), with CW–MFC emerging as a competitive alternative when considering environmental benefits and operational efficiencies (USD 718/m³). This study highlights the potential of hybrid systems, such as CW–MFC, to advance sustainable wastewater treatment technologies by minimizing environmental impacts and enhancing resource recovery, supporting their broader adoption in future water management strategies. Future research should focus on optimizing materials and energy use to improve scalability and feasibility. Full article

Microbial fuel cells (MFCs) generate electricity through the microbial oxidation of organic waste. However, the inherent electrochemical performance of carbon felt (CF) electrodes is relatively poor and requires enhancement. In this study, nickel oxide (NiO) was successfully loaded onto CF to improve its electrode performance, thereby enhancing the electricity generation capacity of MFCs during the degradation of treated wastewater. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy diffusion spectrometer (EDS) analyses confirmed the successful deposition of NiO on the CF surface. The modification enhanced both the conductivity and capacitance of the electrode and increased the number of microbial attachment sites on the carbon fiber filaments. The prepared CF–NiO electrode was employed as the anode in an MFC, and its electrochemical and energy storage performance were evaluated. The maximum power density of the MFC with the CF–NiO anode reached 0.22 W/m², compared to 0.08 W/m² for the unmodified CF anode. Under the C1000-D1000 condition, the charge storage capacity and total charge output of the CF–NiO anode were 1290.03 C/m² and 14,150.03 C/m², respectively, which are significantly higher than the 452.9 C/m² and 6742.67 C/m² observed for the CF anode. These results indicate notable improvements in both power generation and energy storage performance. High-throughput gene sequencing of the anodic biofilm following MFC acclimation revealed that the CF–NiO anode surface hosted a higher proportion of electroactive bacteria. This suggests that the NiO modification enhances the biodegradation of organic matter and improves electricity generation efficiency. Full article

Microbial electrochemical technologies (METs), such as microbial fuel cells (MFCs) and microbial electrolysis cells (MECs), show promise for sustainable energy generation from biomass waste and wastewater. However, further work is necessary for their practical use. In particular, it has been argued that process performances, such as those for organics removal and energy generation, should be substantially improved to catch up with those of existing processes, such as anaerobic digesters. Recent work has reported that bioaugmentation (BA) with electroactive microbes (EAMs) can significantly improve the performance of MFCs and MECs, while previous reports have also documented BA cases with limited impacts. In this article, after summarizing EAMs that have been isolated and characterized as possible BA agents, we comparatively analyze past BA trials for MET processes. Based on the information thus obtained, key factors that should be considered for successful BA are suggested. Full article

Plastic pollution remains a critical global environmental challenge, with conventional disposal methods contributing to ecosystem degradation. Simultaneously, energy scarcity affects numerous rural communities, limiting development opportunities. This study presents an innovative approach that integrates microbial fuel cells (MFCs) with Klebsiella oxytoca to simultaneously degrade plastic waste and generate bioelectricity. The monitoring results over 40 days revealed optimal performance on day 28, with a peak voltage of 0.714 ± 0.026 V and an electric current of 3.149 ± 0.124 mA. The biocatalyst exhibited an electrical conductivity of 140.466 ± 5.180 mS/cm and an oxidation-reduction potential of 109.519 ± 5.35 mV, indicating efficient electron transfer. Furthermore, the MFCs achieved a maximum power density of 11.391 ± 0.814 mW/cm² with a current density of 5.106 mA/cm², demonstrating their potential for sustainable energy production. Fourier transform infrared (FTIR) analysis confirmed structural modifications in the plastic, with decreased vibrational peaks indicative of polymer degradation. Additionally, scanning electron microscopy (SEM) micrographs revealed porosity and surface cracks, highlighting Klebsiella oxytoca’s biodegradation capacity. These findings establish the viability of bioelectrochemical systems for simultaneous waste remediation and renewable energy generation, paving the way for scalable applications in environmental biotechnology. By coupling microbial degradation with electricity production, this research supports the development of sustainable solutions aligned with the principles of circular economy and climate change mitigation. Full article

Volatile organic compounds (VOC) are major contributors to the burgeoning air pollution issue, predominantly from industrial areas, with well-documented environmental and health risks, which demand efficient and sustainable control policies. This review analyzes the current technological challenges and investigates recent developments in biological treatment technologies for VOC-contaminated off-gases, including biofilters, biotrickling filters, and bioscrubber, as well as emerging technologies, such as bioaugmentation and microbial fuel cells (MFCs). Operational performance, economic feasibility, and adaptability to various industrial applications are assessed, alongside opportunities for integration with other technologies, including energy recovery technologies. Biological systems offer considerable advantages regarding cost savings and lower environmental impacts and enhanced operational flexibility, particularly when combined with innovative materials and microbial optimization techniques. Nevertheless, challenges persist, such as choosing the best treatment settings suited to different VOC streams and addressing biofilm control concerns and scalability. Overall, biological VOC treatments are encouraging sustainable solutions, though continued research into reactor design, microbial dynamics, and MFC-based energetic valorization is essential for broader industrial application. These insights cover advancements and highlight the continuous need for innovative prowess to forge sustainable VOC pollution control. Full article

A novel three-dimensional porous biocarbon electrode with exceptional biocompatibility was synthesized via a facile approach using pumpkin as the precursor. The obtained pumpkin-derived biocarbon features a highly porous architecture and serves as an efficient biocarbon electrode (denoted as PBE) in a microbial fuel cell (MFC). This PBE could form robust biofilms to facilitate the adhesion of electroactive bacteria. When used in the treatment of real wastewater, the assembled PBE-MFC achieves a remarkable power density of 231 mW/m², much higher than the control (carbon brush—MFC, 164 mW/m²) under the identical conditions. This result may be attributed to the upregulation of flagellar assembly pathways and bacterial secretion systems in the electroactive bacteria (e.g., Hydrogenophaga, Desulfovibrio, Thiobacillus, Rhodanobacter) at the anode of the PBE-MFC. The increased abundance of nitrifying bacteria (e.g., Hyphomicrobium, Sulfurimonas, Aequorivita) and organic matter-degrading bacteria (e.g., Lysobacter) in the PBE-MFC also contributed to its exceptional wastewater treatment efficiency. With its outstanding biocompatibility, cost-effectiveness, environmental sustainability, and ease of fabrication, the PBE-MFC displays great potential for application in the field of high-performance and economic wastewater treatment. Full article

The intensification of agricultural production due to high global demand has led to uncontrolled waste production from this industry, creating an environmental imbalance due to inadequate waste management. In developing regions, the lack of access to electricity has become a critical problem, affecting people’s health, education, and economy. To address this issue, alternative and sustainable ways of generating electricity have been explored. This research focuses on the potential of using asparagus waste in single-chamber microbial fuel cells (MFCs) at different pH levels (4, 4.7—target, 7, and 9) to achieve optimal performance. It has been demonstrated that using this substrate, the MFC at pH 7 obtained the best results on the seventh day, generating an electric current of 4.859 mA and a maximum voltage of 0.965 V. The substrate showed an oxidation-reduction potential of 312.821 mV, a chemical oxygen demand reduction of 76.47%, and an electrical conductivity of 254.854 mS/cm. Additionally, it managed to generate a power density of 2.149 mW/cm² at a current density of 5.979 mA/cm². MFCs at different pH levels (4, 4.7—target, 7, and 9) demonstrated their potential to generate electrical energy by powering an LED light when connected in series. This research holds promise in promoting sustainable energy solutions for the future. Full article

Nickel-doped iron oxide/graphene oxide powders were synthesized by the co-precipitation method varying the Ni/Fe ratio, and the activity of the materials towards the oxygen reduction reaction in a microbial fuel cell (MFC) was studied. The samples presented X-ray diffraction peaks associated with magnetite, maghemite and Ni ferrite, as well as evidence of hematite. Raman spectra confirmed the presence of maghemite (γ-Fe₂O₃) and NiFe₂O₄. Scanning electron micrographs showed exfoliated sheets decorated with nanoparticles, and transmission electron micrographs showed spherical nanoparticles about 10 nm in diameter well distributed on the individual graphene sheet. The electrocatalytic activity for the oxygen reduction reaction (ORR) was studied by cyclic voltammetry in an air-saturated electrolyte, finding that the best catalyst was the sample with a 1:2 Ni/Fe ratio, using a catalyst concentration of 15 mg·cm⁻² on graphite felt. The 1:2 Ni/Fe catalyst provided an oxygen reduction potential of 397 mV and a maximum oxygen reduction current of −0.13 mA; for comparison, an electrode prepared with GO/γ-Fe₂O₃ showed a maximum ORR of 369 mV and a maximum current of −0.03 mA. Microbial fuel cells with a vertical proton membrane were prepared with Ni-doped Fe₃O₄ and Fe₃O₄/graphene oxide and tested for 24 h; they reached a stable OCV of +400 mV and +300 mV OCV, and an efficiency of 508 mW·m⁻² and 139 mW·m⁻², respectively. The better performance of Ni-doped material was attributed to the combined presence of catalytic activity between γ-Fe₂O₃ and NiFe₂O₄, coupled with lower wettability, which led to better dispersion onto the electrode. Full article

Electro-fermentation (EF) is an emerging bioprocess with the ability to regulate the metabolism of electrochemically active microorganisms. In various fermentation processes, electrodes perform either as an electron acceptor or donor, facilitating the formation and movement of electrons and protons. The bioelectric activity created by external electrodes enhances the metabolic reactions, resulting in a higher yield of value-added chemicals. The conventional fermentation process has a number of limitations in terms of usability and economic feasibility, whereas electro-fermentation presents a hybrid technology, minimizing redox instabilities and enhancing the metabolic process in general to achieve increased product production and a higher biomass yield. Electrochemically active microorganisms such as Geobacter and Shewanella species can carry out the exchange of electrons with electrodes directly or indirectly by using electron mediators. Furthermore, the integration of microbial fuel cells (MFCs) with microbial electrolysis cells (MECs) precludes the need for external manipulation of the fermentation system as the required change in electrochemical gradient is provided by the MFC counterpart. The major beneficial aspects of electro-fermentation include its role as a potential tool for enhancing the production of value-added compounds. The mixed-culture system clearly had a favorable impact on the synthesis of butyric acid from rice straw. Furthermore, cathodic electro-fermentation (CEF) exhibited benefits over anaerobic fermentation, influencing NADH/NAD⁺, enabling a higher product titer, and reducing the accumulation of byproducts. Hence, in this review, we emphasize the importance of electro-fermentation over conventional fermentation for biofuel and biochemical production, covering its fundamentals, interactions, types, future challenges, and ability to provide several benefits to boost the fermentation process, such as the process efficiency and product yield, on an industrial scale. Full article

The aim of this study was to enhance and maintain bioelectricity generation from distillery spent wash using a microbial fuel cell (MFC). Electrode materials play a critical role in the generation of bioelectricity in MFCs. Utilizing double oxidant-treated carbon felts in MFC applications increased current density to 749.56 mA/m² and increased peak power density to 125.23 mW/m². Electrochemical impedance spectroscopy (EIS) analysis further verified the improved electrocatalytic activity observed in the oxidized carbon felt, consistent with the findings from cyclic voltammetry (CV) and polarization curves, thereby confirming the enhanced performance of the oxidized carbon felt electrode. Overall, the study highlights the significance of electrode morphology and surface modifications in influencing microbial adhesion, electron transport, and the overall efficiency of fuel cells using distillery spent wash as a substrate. Full article