Search Results (61)

The projected global energy demand for 2050 drives the imperative search for alternative and environmentally friendly energy sources. An emerging and promising alternative is microbial fuel cells assisted with microalgae. This research evaluated the potential of Chlorella sp. biomass in electricity production using microbial fuel cells (MFCs) with a single chamber and activated carbon and zinc electrodes at the laboratory scale over 20 days of operation. Maximum values of voltage (1271 ± 2.52 mV), current (4.77 ± 0.02 mA), power density (247.514 mW/cm²), current density (0.551 mA/cm²), and internal resistance (200.83 ± 0.327 Ω) were obtained. The biomass-maintained pH values of 7.32 ± 0.03–7.74 ± 0.02 and peaks of electrical conductivity of 2450 ± 17.1 µS/cm and oxidation-reduction potential of 952 ± 20 mV were reached. Meanwhile, cell density and absorbance increased to average values of 2.2933 × 10⁷ ± 1.15 × 10⁶ cells/mL and 3.471 ± 0.195 absorbance units (AU), respectively. Scanning electron microscopy micrographs allowed the observation of filamentous structures of the formed biofilm attached to carbon particles, and energy-dispersive X-ray spectroscopy spectra of the anodes determined the predominance of oxygen, carbon, silicon, aluminum, and iron. Finally, this research demonstrates the great potential of Chlorella sp. biomass for sustainable bioelectricity generation in MFCs. Full article

Corn is one of the most widely produced cereals worldwide, generating large amounts of waste, represents an environmental and economic challenge. In regions such as Africa and rural areas of Peru, access to electricity is limited, affecting quality of life and economic development. This study proposes using microbial fuel cells (MFCs) to convert chicha de jora waste—a traditional fermented beverage made from corn—into electrical energy. Single-chamber MFCs with activated carbon (anode) and zinc (cathode) electrodes were used. A total of 100 ml of chicha de jora waste was added in each MFC, and three MFCs were used in total. The MFCs demonstrated the viability of chicha de jora waste as a substrate for bioelectricity generation. Key findings include a notable peak in voltage (0.833 ± 0.041 V) and current (2.794 ± 0.241 mA) on day 14, with a maximum power density of 5.651 ± 0.817 mW/cm². The pH increased from 3.689 ± 0.001 to 5.407 ± 0.071, indicating microorganisms’ degradation of organic acids. Electrical conductivity rose from 43.647 ± 1.025 mS/cm to 186.474 ± 6.517 mS/cm, suggesting ion release due to microbial activity. Chemical oxygen demand (COD) decreased from 957.32 ± 5.18 mg/L to 251.62 ± 61.15 mg/L by day 18, showing efficient degradation of organic matter. Oxidation-reduction potential (ORP) increased, reaching a maximum of 115.891 ± 4.918 mV on day 14, indicating more oxidizing conditions due to electrogenic microbial activity. Metagenomic analysis revealed Bacteroidota (48.47%) and Proteobacteria (29.83%) as the predominant phyla. This research demonstrates the potential of chicha de jora waste for bioelectricity generation in MFCs, offering a sustainable method for waste management and renewable energy production. Implementing MFC technology can reduce environmental pollution caused by corn waste and provide alternative energy sources for regions with limited access to electricity. 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

The rapid increase in agricultural waste in recent years has led to significant losses and challenges for agro-industrial companies. At the same time, the growing demand for energy to support daily human activities has prompted these companies to seek new and sustainable methods for generating electric energy, which is crucial. Sucrose extracted from fruit waste can act as a carbon source for microbial fuel cells (MFCs), as bacteria metabolize sucrose to generate electrons, producing electric current. This research aims to evaluate the potential of sucrose as an additive to enhance the use of asparagus waste as fuel in single-chamber MFCs. The samples were obtained from CUC SAC in Trujillo, Peru. This study utilized MFCs with varying sucrose concentrations: 0% (Target), 5%, 10%, and 15%. It was observed that the MFCs with 15% sucrose and 0% sucrose (Target) produced the highest electric current (5.532 mA and 3.525 mA, respectively) and voltage (1.729 V and 1.034 V) on the eighth day of operation, both operating at slightly acidic pH levels. The MFC with 15% sucrose exhibited an oxidation-reduction potential of 3.525 mA, an electrical conductivity of 294.027 mS/cm, and a reduced chemical oxygen demand of 83.14%. Additionally, the MFC-15% demonstrated the lowest internal resistance (128.749 ± 12.541 Ω) with a power density of 20.196 mW/cm² and a current density of 5.574 A/cm². Moreover, the microbial fuel cells with different sucrose concentrations were connected in series, achieving a combined voltage of 4.56 V, showcasing their capacity to generate bioelectricity. This process effectively converts plant waste into electrical energy, reducing reliance on fossil fuels, and mitigating methane emissions from the traditional anaerobic decomposition of such waste. Full article

Hexavalent chromium (Cr(VI)) is toxic, carcinogenic, and harmful to biological systems. Common detection methods, such as colorimetry, atomic absorption spectrometry, ion chromatography, and biological systems, can only be used in the laboratory and do not provide real-time feedback. To address these limitations, the current study cloned the ChrB gene, which exhibits high specificity in detecting Cr(VI), and the ChrA gene, which exhibits high Cr(VI) tolerance, into Escherichia coli. This recombinant strain, ChrA–ChrB–E. coli, was integrated into a single-chamber microbial fuel cell for accurate continual monitoring over a wide range of Cr(VI) concentrations. ChrA–ChrB–E. coli thrived in temperatures from 25 °C to 45 °C and pH levels between 5 and 8. Its ability to reduce Cr(VI) remained consistent across Cr(VI) forms, carbon sources, and oxyanions. Cyclic voltammetry was employed to verify the electrical activity of the biosensor. The biosensor exhibited a detection limit of 0.0075 mg/L. Under conditions simulating the regulatory emission limit for Cr(VI) of 0.5 mg/L in industrial wastewater, the biosensor achieved a response time of 20 s during continual operation. When tested with synthetic wastewater containing Cr(VI) concentrations from 0.02 to 150 mg/L, the system exhibited high adaptability and facilitated stable monitoring (relative standard deviation ≤ 2.7%). Additionally, the biosensor’s accuracy (−1.73% to 2.5%) matched that of traditional batch methods, highlighting its suitability for real-time Cr(VI) monitoring in aquatic environments. Full article

The great utility that plastics generate for society has generated a large amount of waste, producing tons of garbage from this material that damages the ecosystem, human health, and farmland. Likewise, the issue of the absence of electricity in low-income areas is critical for society. This research proposes a novel solution to simultaneously solve these two problems, which, through single-chamber microbial fuel cells, introduce plastic waste and the fungus Paecilomyces. The microbial fuel cells (MFCs) showed a maximum electric current of 0.547 ± 0.185 mA with a peak voltage of 0.575 ± 0.106 V on day 36; on this day, the MFCs operated with a pH of 6.524 ± 0.360 and electrical conductivity of 264.847 ± 6.395 mS/cm. These results demonstrate the potential of this system to generate electricity from plastic waste, addressing the issue of electricity scarcity in low-income areas. The chemical oxygen demand was also reduced by 85.47%, indicating the system’s ability to degrade plastic waste. The power density calculated on day 36 was 0.0624 ± 0.0053 mW/cm² at a current density of 0.0052 mA/cm² and an internal resistance of 55.254 ± 7.583 Ω. The reducing action of the fungus on the plastic was demonstrated in the FTIR transmittance spectrum because the characteristic peaks (3378, 2854–2911, 1642, 1472, and 720 cm⁻¹) of the plastic suffered reductions in the final state, and the micrographs of the plastic surfaces showed the lifting of layers and the formation of irregular structures and a decrease in the thickness of the plastic sample of 139.66 ± 4.19 µm. Full article

The mismanagement of plastic waste, organic waste, and the shortage of electricity in remote villages has created significant challenges for industries and governments. Therefore, this research aims to utilize the fungus Trichoderma sp. as a catalyst in microbial fuel cells, where the novelty of the research is the generation of electricity and the degradation of plastic simultaneously. In this study, single-chamber microbial fuel cells were constructed using carbon (anode) and zinc (cathode) electrodes. The substrate consisted of 20 gr of potato waste and 1.5 × 1.5 cm samples of plastic waste, all combined in 390 mL of Bushnell broth, into which Trichoderma sp. was inoculated. The highest electrical readings were recorded on day 23, showing values of 5.648 ± 0.093 mA and 0.479 ± 0.025 V. On the same day, the pH level was measured at 7.046 ± 0.314, and the substrate’s electrical conductivity was found to be 155.135 ± 2.569 mS/cm. Over the 45-day monitoring period, the chemical oxygen demand decreased by 78.67%. The microbial fuel cells achieved a maximum power density of 68.140 ± 2.418 mW/cm² at a current density of 4.719 mA/cm², with an internal resistance of 23.647 ± 1.514 Ω. Analysis of the plastic using FTIR (Fourier Transform Infrared Spectroscopy) revealed a decrease in the intensity of spectral bands associated with hydroxyl groups, C-H structural groups, methyl groups, and C=C bonds. Additionally, SEM (Scanning Electron Microscopy) images demonstrated a reduction in the thickness of the plastic film and the formation of voids and sheets, highlighting the potential of Trichoderma sp. for plastic degradation. 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

The increasing global water pollution leads to the need for urgent development of rapid and accurate water quality monitoring methods. Microbial fuel cells (MFCs) have emerged as real-time biosensors for biochemical oxygen demand (BOD), but they grapple with several challenges, including issues related to reproducibility, operational stability, and cost-effectiveness. These challenges are substantially shaped by the selection of an appropriate air-breathing cathode. Previous studies indicated a critical influence of the cathode on both the enduring electrochemical performance of MFCs and the taxonomic diversity at the electroactive anode. However, the effect of different gas diffusion electrodes (GDE) on 3D-printed single-chamber MFCs for BOD biosensing application and its effect on the bioelectroactive anode was not investigated before. Our study focuses on comparing GDE cathode materials to enhance MFC performance for precise and rapid BOD analysis in wastewater. We examined for over 120 days two Pt-coated air-breathing cathodes with distinct carbonaceous gas diffusion layers (GDLs) and catalyst layers (CLs): cost-effective carbon paper (CP) with hand-coated CL and more expensive woven carbon cloth (CC) with CL pre-applied by the supplier. The results show significant differences in electrochemical characteristics and anodic biofilm composition between MFCs with CP and CC GDE cathodes. CP-MFCs exhibited lower sensitivity (16.6 C L mg⁻¹ m⁻²) and a narrower dynamic range (25 to 600 mg L⁻¹), attributed to biofouling-related degradation of the GDE. In contrast, CC-MFCs demonstrated superior performance with higher sensitivity (37.6 C L mg⁻¹ m⁻²) and a broader dynamic range (25 to 800 mg L⁻¹). In conclusion, our study underscores the pivotal role of cathode selection in 3D-printed MFC biosensors, influencing anodic biofilm enrichment time and overall BOD assessment performance. We recommend the use of cost-effective CP GDL with hand-coated CL for short-term MFC biosensor applications, while advocating for CC GDL supplied with CL as the preferred choice for long-term sensing implementations with enduring reliability. Full article

Wastewater treatment using microbial fuel cells (MFCs) is a potentially useful technology due to its low cost, environmental friendliness, and low sludge production. In this study, a single-chambered air cathode MFC (SCMFC) was developed and investigated regarding its performance and microbial community evolution following nitrate exposure. During long-term operation, diverse denitrifiers accumulated on the electrodes to form a denitrifying MFC (DNMFC) with stable activity for nitrate reduction. The DNMFC presented considerably higher electroactivity, stability, and denitrification rates than the SCMFC. Though energy recovery decreased in the DNMFC by partial organics utilized for heterotrophic denitrification, the electron transfer efficiency increased. Geobacter as the absolutely dominant genus in the SCMFC anode was eliminated and replaced by Azonexus and Pseudomonas in the DNMFC. Furthermore, the biomass of Pseudomonas (151.0 ng/μL) in the DNMFC cathode was five-fold higher than that in the SCMFC, although the bacterial community compositions were quite similar. The DNMFC with highly abundant Pseudomonas exhibited much better performance in terms of electrochemical activity and nitrate removal. The evolution process of functional bacteria from the SCMFC to the DNMFC comprehensively reveals the significant role of denitrifying electroactive bacteria in a bioelectrochemical system for nitrogen-containing wastewater treatment. Full article

Microbial fuel cells provide a promising solution for both generating electricity and treating wastewater at the same time. This review evaluated the effectiveness of using readily available earthen membranes, such as clayware and ceramics, in MFC systems. By conducting a comprehensive search of the Scopus database from 2015 to 2024, the study analyzed the performance of various earthen membranes, particularly in terms of wastewater treatment and energy production. Ceramic membranes were found to be the most effective, exhibiting superior power density, COD removal, and current density, with values of 229.12 ± 18.5 mW/m², 98.41%, and 1535.0 ± 29 mW/m², respectively. The review emphasizes the use of affordable resources like red soil, bentonite clay, CHI/MMT nanocomposites, and Kalporgan soil, which have proven to be effective in MFC applications. Incorporating earthen materials into the membrane construction of MFCs makes them more cost-effective and accessible. Full article

The growing demand for agricultural products has increased exponentially, causing their waste to increase and become a problem for society. Searching for sustainable solutions for organic waste management is increasingly urgent. This research focuses on considering the waste of an Andean tuber, such as Olluco, as a fuel source for generating electricity and becoming a potential sustainable energy source for companies dedicated to this area. This research used Olluco waste as fuel in single-chamber microbial fuel cells using carbon and zinc electrodes. An electric current and electric potential of 6.4 ± 0.4 mA and 0.99 ± 0.09 V were generated, operating with an electrical conductivity of 142.3 ± 6.1 mS/cm and a pH of 7.1 ± 0.2. It was possible to obtain a 94% decrease in COD and an internal resistance of 24.9 ± 2.8 Ω. The power density found was 373.8 ± 28.8 mW/cm² and the current density was 4.96 A/cm². On day 14, the cells were connected in earnest, achieving a power of 2.92 V and generating enough current to light an LED light bulb, thus demonstrating the potential that Olluco waste has to be used as fuel in microbial fuel cells. Full article

Currently, two significant problems involve the government, population, and environment: the accelerated increase in organic waste and the need to replace conventional energy with environmentally sustainable energy. The sustainable use of organic waste is being intensely investigated to generate energy plants that produce alternative sustainable electrical energy beneficial to the population at a low cost. The novelty of this research is given by the use of pepper waste as fuel in the generation of bioelectricity, giving added value to these types of waste, benefiting farmers and companies dedicated to the export and import of these fruits, because they will be able to generate their own electrical energy using their own waste at a lower cost. For this reason, this research uses pepper waste as fuel in single-chamber microbial fuel cells manufactured at a low cost as its primary objective. The maximum values of the electric current (5.118 ± 0.065 mA) and electric potential (1.018 ± 0.101 V) were shown on the fourteenth day, with an optimal operating pH of 7.141 ± 0.134 and electrical conductivity of 112.846 ± 4.888 mS/cm. Likewise, a reduction in the COD was observed from 1210.15 ± 0.89 mg/L to 190.36 ± 16.58 mg/L in the 35 days of monitoring and with a maximum ORP of 426.995 ± 8.615 mV, whose internal resistance was 33.541 ± 2.471 Ω. The peak power density was 154.142 ± 8.151 mW/cm² at a current density of 4.834 A/cm², and the Rossellomorea marisflavi strain was identified with 99.57% identity. Full article

Currently, industry in all its forms is vital for the human population because it provides the services and goods necessary to live. However, this process also pollutes soils and rivers. This research provides an environmentally friendly solution for the generation of electrical energy and the bioremediation of heavy metals such as arsenic, iron, and copper present in river waters used to irrigate farmers’ crops. This research used single-chamber microbial fuel cells with activated carbon and zinc electrodes as anodes and cathodes, respectively, and farmers’ irrigation water contaminated with mining waste as substrate. Pseudomonas stutzeri was used as a biocatalyst due to its ability to proliferate at temperatures between 4 and 44 °C—at which the waters that feed irrigated rivers pass on their way to the sea—managing to generate peaks of electric current and voltage of 4.35 mA and 0.91 V on the sixth day, which operated with an electrical conductivity of 222 mS/cm and a pH of 6.74. Likewise, the parameters of nitrogen, total organic carbon, carbon lost on the ignition, dissolved organic carbon, and chemical oxygen demand were reduced by 51.19%, 79.92%, 64.95%, 79.89%, 79.93%, and 86.46%. At the same time, iron, copper, and arsenic values decreased by 84.625, 14.533, and 90.831%, respectively. The internal resistance values shown were 26.355 ± 4.528 Ω with a power density of 422.054 mW/cm² with a current density of 5.766 A/cm². This research gives society, governments, and private companies an economical and easily scalable prototype capable of simultaneously generating electrical energy and removing heavy metals. Full article

This investigation examined the role of shear stress on the dynamic development of microbial communities within anodic biofilms in single-chamber microbial fuel cells (MFCs). Bacterial attachment to surfaces, often regarded as a crucial step in biofilm formation, may significantly contribute to the selection of electroactive bacteria (EAB). It is well established that hydrodynamic forces, particularly shear forces, have a profound influence on bacterial adhesion. This study postulates that shear stress could select EAB on the anode during the adhesion phase by detaching non-EAB. To examine this hypothesis, MFC reactors equipped with a shear stress chamber were constructed, creating specific shear stress on the anode. The progression of adhesion under various shear stress conditions (1, 10, and 50 mPa) was compared with a control MFC lacking shear stress. The structure of the microbial community was assessed using 16S rRNA gene (rrs) sequencing, and the percentage of biofilm coverage was analyzed using fluorescence microscopy. The results indicate a significant impact of shear stress on the relative abundance of specific EAB, such as Geobacter, which was higher (up to 30%) under high shear stress than under low shear stress (1%). Furthermore, it was noted that shear stress decreased the percentage of biofilm coverage on the anodic surface, suggesting that the increase in the relative abundance of specific EAB occurs through the detachment of other bacteria. These results offer insights into bacterial competition during biofilm formation and propose that shear stress could be utilized to select specific EAB to enhance the electroactivity of anodic biofilms. However, additional investigations are warranted to further explore the effects of shear stress on mature biofilms. Full article