Search Results (75)

The increasing demand for sustainable energy and efficient wastewater treatment has driven interest in single-chamber microbial fuel cells (SCMFCs) as integrated systems for bioelectricity generation and waste remediation. This study evaluates untreated agro-industrial byproduct olive mill wastewater (OMW) as a substrate in SCMFCs. It investigates the performance of activated biochar derived from olive pomace coated on stainless-steel mesh (ACB/SSM) as a low-cost cathode material. A synthetic media was used as a control. Electrochemical performance was assessed using voltage profiles, polarization analysis, power density, chemical oxygen demand (COD%) removal, and coulombic efficiency (CE%). The synthetic media achieved higher peak voltage (0.647 ± 0.026 V) and power density (46.05 mW m⁻²), whereas OMW showed more stable voltage output and lower internal resistance. OMW exhibited superior initial COD removal (74%) and a gradual increase in CE% up to 63% over successive cycles. In contrast, synthetic media exhibited a consistent COD% of 64%; its CE% removal improved to 61%. These results demonstrate that, despite lower peak power, OMW provides a more stable and sustainable substrate for long-term SCMFC operation. The use of waste-derived biochar cathodes further enhances system feasibility by reducing cost and supporting circular economy principles. This study highlights the potential of OMW-based SCMFCs as a practical approach for simultaneous wastewater treatment and renewable energy recovery. Full article

This study presents a low-cost, small-scale single-chamber microbial fuel cell (MFC) toxicity biosensor fabricated on a printed circuit board (PCB) and a 3D-printed chamber with a volume of 120 μL. The anode consists of a screen-printed carbon electrode on the PCB, while the air cathode is a carbon paper electrode. To address poor adhesion of microorganisms to the smooth anode surface, femtosecond laser processing was used to fabricate a micropore array with 40 μm pores on the electrode. This method can create micropores on the anode surface without damaging the screen-printed electrodes, the PCB substrate, or the pads. These micropores increase the anode’s surface area and hydrophilicity, allowing more microbial coatings to firmly adhere to its surface. In this study, the MFC utilised Rhizobium rosettiformans W3, extracted from activated sludge at a wastewater treatment plant, as the anode microorganism. Its aerobic nature simplifies the design of MFCs, enabling a single-chamber structure and miniaturisation. Using formaldehyde solution as a toxicity sample to test the biosensor’s performance, a 0.1% concentration significantly reduced the sensor’s output power. Full article

Hexavalent chromium (Cr(VI)) is a high-priority environmental pollutant due to its strong oxidizing properties, which cause DNA damage and other severe health effects. Conventional detection methods are often costly and lack real-time monitoring capabilities, creating a strong demand for cost-effective, real-time biosensors that meet industrial requirements. In this study, we developed a novel biosensor for continuous Cr(VI) monitoring using a single-chamber microbial fuel cell (MFC). The biological element is an engineered Escherichia coli strain (ChrA-ChrB-E. coli), constructed by introducing Cr(VI)-resistant (ChrA) and Cr(VI)-reducing (ChrB) genes. The presence of Cr(VI) affects bacterial metabolism and electron transfer within the MFC, generating a measurable signal proportional to the contaminant’s concentration. The biosensor demonstrated robust performance and characteristics. The recombinant strain retained functional activity after 450 days of storage at −20 °C. The system exhibited high sensitivity and excellent linearity (R² ≥ 0.999) across a broad Cr(VI) concentration range of 0.015–200 mg/L. During continuous monitoring of chrome tanning and electroplating wastewater, measurements deviated by less than 2.33% from the standard diphenylcarbazide (DPC) method; electroplating deviation was further reduced to −0.69% with EDTA pretreatment. In fishery water, the deviation was higher (−7.12%) due to dissolved oxygen (DO) interference but was reduced to −0.75% after mechanical stirring to remove DO. The biofilm bacterial community remained highly stable over six months in both wastewater types, with the inoculated ChrA-ChrB-E. coli strain maintaining dominance (>99.6%). These results substantiate the feasibility of using this biosensor for continuous, online, real-time detection of Cr(VI) in actual wastewater environments. Full article

Microbial fuel cells (MFCs) convert the chemical energy of biomass into electricity through microbially driven redox reactions. We evaluated a single-chamber, membrane-less MFC fed with sugarcane molasses and inoculated with a two-member consortium: Saccharomyces cerevisiae (glucose → ethanol fermentation) and Acetobacter aceti (ethanol → acetate oxidation). Three anode–cathode pairs were tested—bronze–Zn, copper–Zn, and graphite–Zn—across 27 units and 20 operating cycles. During ethanol oxidation, A. aceti oxidizes ethanol to acetic acid and, in our configuration, this biocatalytic step is designed to contribute electrons to the bronze, copper, or graphite anodes. These electrons, together with those generated by galvanic reactions in the electrode pair, flow through the external circuit to the zinc cathode, where oxygen reduction closes the circuit. The cells reached open-circuit potentials > 0.8 V, with performance following the hierarchy graphite–Zn > copper–Zn > bronze–Zn, consistent with the superior biocompatibility and lower corrosion of carbonaceous anodes. Multivariate analysis using PLS-SEM confirmed that redox indicators and electrode composition were strong determinants of voltage output (R² = 0.911) and demonstrated high predictive relevance (Q² = 0.906) for the voltage construct. These findings show that coupling yeast fermentation with acetic acid–bacteria oxidation enables synthetic-mediator-free electron transfer in a simple single-chamber configuration and shows that electrode material selection is a primary lever for achieving stable potentials for biomass valorization. Full article

Microbial fuel cell (MFC) technology represents a promising bioelectrochemical approach for the simultaneous generation of electricity and treatment of high-strength wastewater. However, the performance of MFCs strongly depends on the metabolic potential and synergistic interactions of the inoculated microbial community. This study evaluated the electrochemical activity and COD removal efficiency of three individual bacterial strains, Lysinibacillus sphericus A1, Bacillus cereus A2 and Lactococcus lactis A4, compared with a developed consortium under long-term operation using poultry slaughterhouse wastewater as a substrate. All inocula were tested in dual-chamber MFCs for 30 days, and performance indicators included power output, voltage, and removal of chemical oxygen demand (COD). The consortium showed the highest power of 170 mW/m² and the optimal voltage–current ratio at a current of 900 mA/m² and 245 mV under decreasing external resistance from 1000 to 50 Ω. The highest COD removal (84.4%) was also recorded, surpassing all pure cultures and demonstrating a significant improvement compared with B. cereus A2 and L. lactis A4. Meanwhile, the lowest power of 52 mA/m² was recorded during testing of L. lactis A4, at 650 mA/m² and 120 mV. Compared with single cultures, the consortium produced approximately 15% higher power density than L. sphericus A1, about 29% higher than B. cereus A2, and more than threefold higher than L. lactis A4. This study highlights the potential of a consortium as an efficient biocatalyst for MFC-mediated wastewater treatment and suggests that selecting complementary strains with diverse metabolic functions can substantially improve system performance. Full article

This study developed a novel worm-assisted membrane bioelectrochemical reactor (W-MBER) that integrates aquatic worms and a single-chamber sediment microbial fuel cell into a membrane bioreactor (MBR) to address challenges in energy recovery, sludge reduction, and membrane fouling. The system achieved a stable output of 290 mV at an external resistance of 250 Ω and a maximum power density of 0.013 W/m² while maintaining high removal efficiencies for chemical oxygen demand (93.57%) and ammonia nitrogen (98.61%). Furthermore, the TN removal efficiency was 12.93% higher than that in the conventional MBR (C-MBR), attributed to the anodic anoxic microenvironment. The synergy of worm predation and the bioelectrochemical process reduced sludge production by 28.51% and extended the filtration cycle by 43.75%, indicating significant sludge reduction and membrane fouling mitigation. Mechanistic analysis revealed that the W-MBER system decreased protein content and protein/polysaccharide ratios in soluble microbial products (SMPs) and extracellular polymeric substances (EPSs), and the hydrophobicity of SMPs, EPSs, and sludge flocs was reduced, resulting in a lower free energy for their interaction with membrane. The foulants in the W-MBER encountered higher energy barriers and lower secondary energy minimums when approaching the membrane, indicating a lower membrane fouling propensity. These results demonstrate the promise of W-MBER for sustainable wastewater treatment. Full article

This study addresses two critical challenges in rural Peru: the mismanagement of agro-industrial waste and the limited access to electricity. Over 40,000 tons of Cucumis sativus (cucumber) waste are generated annually in Peru, most of which is discarded without valorization. Microbial fuel cells (MFCs) offer a sustainable solution by converting organic waste into bioelectricity via electrogenic microorganisms. To evaluate the bioenergy potential of cucumber waste, three single-chamber MFCs were constructed using graphite and zinc electrodes under an external resistance of 100 ohms. The systems were inoculated with acclimated microbial consortia, and electrical, physicochemical, and microbiological parameters were monitored over 35 days. Results showed a maximum voltage of 0.589 V, a peak current of 2.292 mA, and a power density of 0.622 mW/m². Chemical oxygen demand (COD) was reduced by over 80%, and oxidation-reduction potential (ORP) reached 459.76 mV. Internal resistance was 24.515 ± 1.237 Ω, indicating high energy efficiency. Taxonomic analysis revealed a predominance of Gammaproteobacteria, Bacilli, Bacillus, Acetobacter, and Clostridium, confirming a functionally diverse and electroactive microbial community. These findings demonstrate that cucumber waste is a viable substrate for MFCs and support its potential for integrated waste valorization and decentralized bioenergy generation in rural Peruvian contexts. Full article

Aniline aerofloat (AAF) is a typical refractory organic regent residual in mineral processing wastewater (MPW). Microbial fuel cells (MFCs) have been proven highly effective in degrading organic contaminants and resource recovering in wastewater treatment processes. However, AAF biodegradation potential and the related mechanisms in MFC systems remain poorly understood. In this study, the degradation of AAF, electricity generation performance and microbial mechanisms in the single-chamber MFC (sMFC) were confirmed. Affecting factors including AAF concentration, operation resistor, and pH were analyzed. The results indicated that under initial sodium acetate/AAF concentration of 300/100 mg/L, pH 7.0 and an operation resistor of 200 Ω, the AAF removal efficiency achieved 72.7 ± 1.6% with an output voltage of approximately 232 mV. The existence of AAF increased the relative abundance of electroactive bacteria, especially Comamonas and Geobacter. Functional prediction analysis showed that carbohydrate metabolism pathways was the dominant process. The relative abundance of N-respiration and S-respiration functional groups significantly increased, thereby improving COD and AAF removal. This study demonstrated that the MFC anode was beneficial to AAF degradation and provided an alternative route for the biodegradation of organic mineral processing reagents. To our knowledge, this is the first study evaluating AAF biodegradation performance in the MFC system. Full article

This work investigated the use of microbial fuel cells (MFCs) for the degradation of polyethylene terephthalate (PET) and the simultaneous generation of electricity. The study implemented two separate single-chamber MFCs, one with a co-culture of Ideonella sakaiensis and Geobacter sulfurreducens (I.S-G.S) and the other with Ideonella sakaiensis and activated sludge (I.S-AS). The effectiveness of microplastic (MP) degradation was assessed based on the electroactivity of the anodic biofilm, the reduction in particle size, and the decrease in PET mass. Both systems achieved a significant reduction in MP size and mass, with the I.S-AS system notably surpassing the I.S-G.S in terms of efficiency and electricity generation. The I.S-AS system achieved a 30% mass reduction and 80% size reduction, along with a peak voltage of 222 mV. The study concludes that MFCs, particularly with the activated sludge co-culture, offer a viable and more environmentally friendly alternative for MP degradation and energy recovery. These findings suggest a promising direction for improving waste management practices and advancing the capabilities of bio-electrochemical systems in addressing plastic pollution. Further research is recommended to optimize the operational conditions and to test a broader range of MP sizes for enhanced degradation efficacy. Full article

Limited access to electricity and high levels of CO₂ emissions—over 35 billion metric tons in recent years—highlight the urgent need for sustainable energy solutions, particularly in rural areas dependent on polluting fuels. To address this challenge, three single-chamber microbial fuel cells (MFCs) with carbon anodes and zinc cathodes were designed and operated for 35 days in a closed circuit. Voltage, current, pH, conductivity, ORP, and COD were monitored. FTIR-ATR spectroscopy (range 4000–400 cm⁻¹) was applied to identify structural changes, and polarization curves were constructed to estimate internal resistance. The main FTIR peaks were observed at 1027, 1636, 3237, and 3374 cm⁻¹, indicating the degradation of polysaccharides and hydroxyl groups. The maximum voltage reached was 0.961 ± 0.025 V, and the peak current was 3.052 ± 0.084 mA on day 16, coinciding with an optimal pH of 4.977 ± 0.058, a conductivity of 194.851 ± 2.847 mS/cm, and an ORP of 126.707 ± 6.958 mV. Connecting the three MFCs in series yielded a total voltage of 2.34 V. Taxonomic analysis of the anodic biofilm revealed a community dominated by Firmicutes (genus Lactobacillus: L. acidophilus, L. brevis, L. casei, L. delbrueckii, L. fermentum, L. helveticus, and L. plantarum), along with Bacteroidota and Proteobacteria (electrogenic bacteria). This microbial synergy enhances electron transfer and validates the use of carrot waste as a renewable source of bioelectricity for low-power applications. Full article

Microalgae are promising candidates for renewable biofuel production and nutrient-rich animal feed. Cultivating microalgae using wastewater can lower production costs but often results in biomass contamination and increases downstream processing requirements. This study presents a novel system that integrates an algae cultivator (AC) with a single-chamber microbial fuel cell (MFC) equipped with photosynthetic and air-cathode functionalities, separated by a ceramic membrane. The system enables the generation of electricity and production of clean microalgae biomass concurrently, in both light and dark conditions, utilizing wastewater as a nutrient source and renewable energy. The MFC chamber was filled with simulated potato processing wastewater, while the AC chamber contained microalgae Chlorella vulgaris in a growth medium. The ceramic membrane allowed nutrient diffusion while preventing direct contact between algae and wastewater. This design effectively supported algal growth and produced uncontaminated, harvestable biomass. At the same time, larger particulates and undesirable substances were retained in the MFC. The system can be operated with synergy between the MFC and AC systems, reducing operational and pretreatment costs. Overall, this hybrid design highlights a sustainable pathway for integrating electricity generation, nutrient recovery, and algae-based biofuel feedstock production, with improved economic feasibility due to high-quality biomass cultivation and the ability to operate continuously under variable lighting conditions. 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

Plastic pollution is an increasingly pressing environmental concern due to its persistence in ecosystems. To address this issue, this study evaluates polyethylene biodegradation and bioelectricity generation using Aspergillus ochraceopetaliformis in microbial fuel cells (MFCs). Single-chamber MFCs were designed (three) with carbon and zinc electrodes, where the fungus was cultivated in a nutrient-rich medium to enhance its metabolic activity. Parameters such as pH, power density, and FTIR spectra were monitored to assess plastic biodegradation. The results demonstrated a significant reduction in polyethylene mass and structure, along with a maximum generation of 0.921 V and 4.441 mA on day 26, with a power density of 0.148 mW/cm² and a current of 5.847 mA/cm². The optimal pH for fungal activity in the MFC was recorded at 7.059. Furthermore, FTIR analysis revealed a decrease in peak intensity at 1470 cm⁻¹ and 723 cm⁻¹, indicating structural modifications in the treated plastics. Furthermore, microbial fuel cells connected in series successfully powered an LED bulb, generating a maximum voltage of 2.78 V. These findings confirm the feasibility of using Aspergillus ochraceopetaliformis for biodegradation and bioelectricity generation, although practical applications require further optimization of system conditions and improvements in long-term stability. This research contributes to the development of biotechnological strategies for plastic waste management, sustainable integrating approaches with energy potential. 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

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