Search Results (495)

Salt-bridge kefir-derived microbial fuel cells (MFCs) provide a low-cost platform for studying fermentation-linked electrical output, but their behavior is often evaluated through isolated current or voltage traces rather than integrated reactor-state evidence. This study assessed laboratory-scale double-chamber MFCs operated under fed-batch conditions with a kefir-derived mixed consortium and molasses-based substrate. Thirty-three independent reactors, including graphite- and graphene-anode configurations, were monitored from day 0 to day 20, generating 693 reactor-day observations. Electrical, redox, temperature, substrate-related, UV–Vis soluble-phase, baseline sequencing, endpoint SEM, FTIR functional-group evidence, and semimechanistic descriptors were integrated to diagnose reactor evolution and predict fixed-condition current output. Current declined from 0.8985 to 0.1133 mA, residual glucose-equivalent decreased from 5.3124 to 0.0127 g L⁻¹, and the glucose-consumption fraction reached 0.9977. Fixed-condition apparent power decreased from 0.8636 to 0.0856 mW, while cumulative charge and cumulative apparent energy averaged 595.02 C and 456.69 J per reactor. FTIR bands supported carbohydrate/EPS, organic-acid, and proteinaceous-matrix signatures consistent with a fermentation–redox–biofilm cascade. The random-forest model showed strong grouped cross-validation performance (R² = 0.956, RMSE = 0.082 mA, MAE = 0.060 mA, slope = 1.009, r = 0.978). This work supports state-aware current and fixed-condition power-output prediction in kefir-driven MFCs without claiming maximum power-density or complete electrochemical characterization. Full article

Geobacter sulfurreducens is a model bacterium widely used in microbial fuel cell (MFC) research due to its efficient extracellular electron transfer. However, the high cost of synthetic media limits the scalability of these systems, making agro-industrial byproducts like cheese whey a sustainable alternative. This study evaluated cheese whey as a growth medium for G. sulfurreducens and its influence on biofilm development on graphite bars electrodes. Bacterial growth kinetics and biofilm architecture were characterized using Atomic Force Microscopy (AFM) as the primary quantitative tool, supplemented by Scanning Electron Microscopy (SEM). Growth curves revealed a diauxic-like transition within the first 48 h, with high cell viability (94%). AFM analysis demonstrated a non-linear topographical evolution: an initial attachment phase was followed by a peak in structural heterogeneity at 14 days (S_q = 683.08 nm), eventually reaching a mature, confluent state at 21 days with a maximum thickness of ~8 μm. Energy-Dispersive Spectroscopy (EDS) confirmed an organic and mineral matrix consistent with bacterial biomass and whey components. These results demonstrate that cheese whey effectively supports the growth of G. sulfurreducens and the formation of structurally complex biofilms, highlighting its potential as a low-cost substrate for microbial cultivation and dairy waste valorization. Full article

Pig farming generates high-strength piggery wastewater (PWW) with extreme organic and nutrient concentrations. This research evaluated an integrated treatment system combining Vertical Flow Constructed Wetlands (VFCW), Microbial Fuel Cells (MFC), and Microalgae Photobioreactors (PBR) to enhance resource recovery, evaluate bio-electrochemical activity, and produce microalgal biomass. Findings showed that hydraulic saturation in the VFCW–MFC stage enhanced the open-circuit voltage response, reaching a maximum of 539 mV, indicative of bio-electrochemical activity. The optimized VFCW–MFC configuration, featuring pulsed feeding, achieved removals of total suspended solids (TSS, 83%) and chemical oxygen demand (COD, 69%). This integrated pretreatment mitigated ammonia toxicity and turbidity, enabling the subsequent cultivation of Tetradesmus obliquus microalga, reaching biomass yields of 1.1–1.3 g L⁻¹ while providing crucial tertiary polishing. Overall, the combined VFCW–MFC–PBR system achieved removal efficiencies exceeding 90% for total Kjeldahl nitrogen (TKN) and approximately 80% for COD. This synergistic approach successfully transforms PWW liabilities into valuable assets, including nutrient-rich biomass and bio-electrochemical activity, underscoring the potential of VFCW–MFC–PBR for sustainable wastewater management. Full article

Floating wetlands have emerged as a sustainable alternative for improving water quality, and although some studies have investigated their performance, there is still much to be understood regarding their integration with energy-generating technologies. This study evaluated a combined system of floating wetlands and microbial fuel cells (MFCs) for treating real wastewater and generating bioelectricity. Experiments were conducted in batch mode to simulate application in natural water bodies, using real wastewater collected on different dates. As a result of the natural variability of the influent, initial chemical oxygen demand (COD) concentrations of 405 and 289 mg/L were observed. Performance was assessed in terms of organic matter and nitrogen removal, as well as voltage generation. COD removal efficiencies reached 50% and 69% for the higher and lower organic loads, respectively, indicating improved treatment at reduced concentrations. Maximum removals of 56% for ammoniacal nitrogen (NH₃-N) and 40% for total nitrogen (TN) were achieved, reflecting moderate nutrient removal capacity. Voltage generation was sustained for approximately 21 days, confirming stable bioelectrochemical activity, and power output was found to depend on the organic load serving as substrate for electrogenic microorganisms. Overall, the system represents a viable approach for wastewater treatment with the added benefit of energy recovery, although its performance is influenced by influent characteristics and operation conditions. Full article

Microbial fuel cells (MFCs) are emerging as biomimetic bioelectrochemical systems that emulate naturally occurring microbial electron-transfer pathways for stimulus bioenergy generation and wastewater remediation. In this study, food–vegetable leachate (FVL) and sugarcane bagasse-derived biol were evaluated in combination with carbon fiber (CF) and biochar-modified carbon fiber (BCF) electrodes used as membrane components in MFCs. Four configurations, in duplicate, were constructed by coupling two substrates (biol or FVL) with two membrane types (CF and BCF). All systems exhibited progressive anodic acidification and up to a 55% increase in electrical conductivity. The highest voltage output was achieved in MFC-BL-2 (404.59 mV), followed by MFC-FL-1, driven by synergistic interactions between the substrate and biochar-enhanced conductive networks. MFC-FL-1 also demonstrated superior contaminant removal performance, achieving 60% COD reduction, 36% BOD reduction, and 50% NH₄⁺–N removal. SEM–EDS analysis confirmed that biochar-modified electrodes developed a porous structure and substantially enhanced microbial adhesion. FVL-fed systems formed dispersed electroactive biofilms that facilitated electron transfer, whereas biol-fed systems developed compact biofilms that constrained electron flux. By integrating waste-derived lignocellulosic materials with electroactive microbial consortia, this work advances a biomimetic circular bioengineering platform for sustainable bioelectrochemical recovery and wastewater remediation. Full article

The strategy of enhancing biocatalytic activity through the modification of natural cells with nanomaterials has overcome the intrinsic catalytic bottlenecks of bacteria, making significant contributions to energy production and pollution treatment. However, chemically engineered biocatalyst systems remain in their early stages of development. Herein, we report a simple and straightforward strategy for constructing an efficient biocatalyst by incorporating carbon quantum dots (CDs) into Escherichia coli (E. coli) to enhance the oxygen reduction reaction (ORR) at the cathode of microbial fuel cells (MFCs). The introduction of CDs significantly accelerates extracellular electron transfer and metabolic activity, markedly increases intracellular adenosine triphosphate (ATP) levels, and promotes substrate utilization. Furthermore, the engineered E. coli exhibits enhanced surface adhesion and increased electronegativity. Electrochemical measurements demonstrate superior ORR activity, delivering a maximum current density of 3.1 mA·cm⁻² and an onset potential of 0.67 V, outperforming many previously reported biocatalysts. When applied in an MFC system, the modified biocatalyst achieves a maximum power density of 325 μW·cm⁻², placing it among the highest-performing systems reported to date. This work provides a facile and cost-effective approach for improving MFC performance and offers a promising design strategy for next-generation biohybrid catalysts. Full article

The increasing worldwide demand for sustainable energy and effective waste management has heightened interest in solutions. Microbial fuel cells (MFCs) represent a potential category of bioelectrochemical systems that directly transform the chemical energy contained in organic waste into electrical energy via the metabolic processes of electroactive microorganisms. In the last twenty years, significant advancements have occurred in the comprehension of extracellular electron transfer (EET) mechanisms, biofilm formation, microbial community dynamics, electrode material engineering, and reactor design, resulting in marked enhancements in power density and wastewater treatment efficacy. Despite these breakthroughs, the extensive deployment and commercialization of MFC technology are constrained by various hurdles, including inadequate energy recovery, elevated material and fabrication expenses, operational instability, and the intricacies of system scale-up. This cutting-edge analysis offers a thorough evaluation of recent advancements in MFCs and their incorporation with sophisticated technology for waste management and energy generation. Focus is directed towards essential bioelectrochemical principles, microbial and biofilm engineering techniques, sophisticated electrode and membrane materials, reactor designs, and hybrid MFC systems integrated with anaerobic digestion, microbial electrolysis, and advanced oxidation methods. Ultimately, emerging trends, significant knowledge deficiencies, and future research goals are defined to inform the advancement of next-generation MFC systems that support circular economy and net-zero energy initiatives. Full article

Microbial fuel cells (MFCs) are promising bioelectrochemical systems for simultaneous wastewater treatment and energy recovery. However, their practical application is still limited by insufficient power output and weak transient energy-supply capability under fluctuating operational conditions. Herein, a bifunctional CF/MXene/FeS composite anode was fabricated through a one-step hydrothermal strategy to simultaneously enhance electricity generation and capacitive charge storage in MFCs. Unlike conventional bioanode modifications that primarily target conductivity enhancement alone, the constructed hierarchical composite integrates conductive MXene nanosheets and electroactive FeS phases to synergistically improve extracellular electron transfer and interfacial charge-storage behavior. The modified electrode exhibited enhanced surface roughness, abundant electroactive sites, and improved biofilm-supporting interfaces. Benefiting from the integrated conductive and electroactive composite framework, the CF/MXene/FeS anode achieved a maximum power density of 1.69 W/m², which was 70.7% higher than that of pristine CF, together with an increased open-circuit voltage of 0.711 V. In addition, the composite electrode delivered a high total charge density of 13,192.09 C/m² under the C900/D900 condition. Microbial community analysis further revealed substantial enrichment of electroactive bacteria, with the relative abundance of Geobacter increasing from 0.0058% to 22.84%. This work provides a promising strategy for integrating electricity generation and transient energy storage in bioelectrochemical systems, offering potential applications for energy-buffered MFCs under fluctuating power-demand conditions. Full article

Demographic growth and the global environmental crisis have intensified the need to reconcile energy generation with the protection of terrestrial ecosystems. Traditional organic waste management systems are inefficient in handling high pollutant loads, leading to uncontrolled methane emissions and degradation of soil and water. In response to this challenge, the present study aimed to conduct a critical review of how Microbial Fuel Cells (MFCs) valorize biomass to align climate action (SDG 13) with the protection of terrestrial life (SDG 15). Through a bibliometric analysis of the Scopus database (2010–2026), supported by tools such as Bibliometrix, 460 documents were examined, complemented by a systematic literature review addressing biomass types, microbial interactions, and electrode modifications. The main findings indicate that MFC research is currently in an exponential growth phase (R² = 0.99954), with Environmental Sciences (23%) and Chemical Engineering (15%) as the predominant fields. Industrial and plant residues exhibit the highest bioelectric potential, while mixed microbial consortia—particularly fungal–bacterial synergies—outperform pure cultures in degradative efficiency and energy generation, reaching up to 1760 mW/m² with Geobacter sulfurreducens bioaugmentation. Electrode modification with nanomaterials such as NiO or MWCNTs substantially enhances charge transfer. Standardization of measurement protocols, ecological impact assessment of nanomaterials, and evaluation of the economic–environmental feasibility of MFC-integrated biorefineries are recommended to ensure scalability and effective contributions to SDGs 13 and 15. Full article

A livestock farm in southern Taiwan produces wastewater with high concentrations of nitrogen and organics, which inhibit anaerobic methanogens and limit the efficiency of its biogas system. To enhance energy recovery, this study developed a liter-scale microbial fuel cell (MFC) system aimed at harvesting electricity from livestock wastewater, serving as a supplementary energy recovery pathway alongside the biogas process. According to the five analyses, the chemical oxygen demand (COD) of raw wastewater ranged from 14 to 21 g L⁻¹, with acetate concentrations ranging between 40 and 112 mM. Propionate and butyrate were consistently below 32 mM and 18 mM, respectively. Ammonium ranged from 1.1 to 1.7 g-N L⁻¹, indicating the wastewater’s high organic load and elevated nitrogen content. Two liter-scale MFCs, ch5 and ch7, were operated for over 70 d. From days 7 to 28, both MFCs employed a fill-and-draw mode, achieving optimal COD removal exceeding 80%. After resolving leakage issues between days 30 and 40, the system was restarted on day 40, yielding 76% (ch5) and 82% (ch7) of COD removal. Continuous operation began on day 59, and both reactors maintained COD removal rates above 80% for most of the subsequent two-week period. The best power outputs for ch5 and ch7 reached 1.11 and 0.82 W m⁻³, respectively. Although both liter-scale reactors achieved COD removal and measurable power output, the most important finding was obtained from the inoculum comparison experiments. After 54 days of acclimating to raw wastewater solids, no significant current was observed. In contrast, digestate solids acclimated with carbon powder for 22 d produced a peak current of 42.5 A m⁻³ at 147 h, with COD removal rates of 67–73% and complete removal of organic acids. The key conclusion of this study is that anaerobic digestate exhibits electroactive microbial potential, whether operated in liter-scale reactors or acclimated with carbon powder. Further investigation into the microbial community structure is warranted to optimize system performance. Full article

Microbial fuel cells (MFCs) offer a promising pathway for treating wastewater while simultaneously generating electricity; however, they remain largely pilot-scale technology due to persistent limitations, such as low power density. Microalgae can act as in situ oxygen suppliers in the cathode chamber of dual chamber MFCs, enhancing electricity generation while facilitating nutrient removal. This study compares the performance of cathodic microalgae in MFCs utilizing either a cation exchange membrane (CEM) or an anion exchange membrane (AEM). Raw municipal wastewater collected from the preliminary tank was used as the anodic substrate, while pre-cultivated Chlorella vulgaris (optical density ≈ 0.42) was introduced into the cathode chambers. The performance of both configurations was constantly monitored through various analytical methods. The AEM-based MFC produced significantly higher and more stable voltages (avg. 0.05 volts; peak ≈ 0.11 volts) and achieved a 0.95 mW/m² peak power density, compared to the CEM-based MFC, which produced lower voltages (avg. 0.01 volts; peak ≈ 0.06 volts) and achieved a 0.25 mW/m² peak power density. No significant differences in nutrient removal rates were found among the membranes. Findings demonstrate the superiority of AEM configurations for microalgae-assisted MFCs, establishing a more viable framework for potential large-scale wastewater treatment applications. Full article

The pulping and paper-making (P&P) industry is one of the world’s largest manufacturing sectors, yet it is plagued by high water/energy consumption and massive discharge of highly polluted wastewater. The effluents from pulping, bleaching and papermaking processes are characterized by high chemical oxygen demand (COD), intense color, toxic adsorbable organohalides (AOX) and abundant refractory lignin, which pose significant threats to aquatic ecology and human health. Although conventional physical, chemical and biological treatments have been widely applied, they are constrained by insufficient degradation efficiency toward recalcitrant organics, high cost and potential secondary pollution. In recent years, electrocatalytic technologies including electrocatalytic oxidation, electroreduction and their integrated processes, have demonstrated superior efficacy in specific scenarios of P&P wastewater treatment, such as lignin degradation, toxic side-streams treatment, pretreatment for enhancing biodegradability, and polishing steps in integrated treatment systems, which are not universally applicable solutions for P&P wastewater remediation. Meanwhile, biomass fuel cells typified by direct biomass fuel cells (DBFC) and microbial fuel cells (MFC) provide promising pathways for synchronous pollutant removal, energy production and resource recovery. Representative studies have reported COD removal efficiencies of 60–100% for electrochemical and advanced oxidation processes, while integrated electro-Fenton–biological treatment increased the BOD/COD ratio from 0.34 to 0.52 and achieved an overall COD removal of 94%. It should be noted that these advanced electrochemical technologies are still confronted with challenges in industrial scale-up, high energy and electrode material costs, and stable continuous operation. This review systematically elaborates on the physicochemical properties, generation mechanisms and environmental impacts of P&P wastewater, comprehensively summarizes the mainstream treatment technologies including physicochemical, biological, electrochemical and integrated processes, and analyzes their reaction mechanisms, efficiencies and applicable conditions. Particular emphasis is placed on electrocatalytic treatment and bio-electrochemical valorization strategies. This review is anticipated to provide a valuable reference for the efficient and targeted treatment as well as sustainable utilization of P&P wastewater, thereby supporting the green and low-carbon development of the P&P industry. Full article

The valorization of dairy industry by-products and simultaneous energy recovery remain important challenges in sustainable waste management. In this study, waste buttermilk was evaluated as a substrate for bioelectricity generation in a microbial fuel cell (MFC) equipped with a gas diffusion anode (GDE) and non-precious metal cathodes. Three electrode configurations were investigated: GDE/GDE, GDE/Cu–B, and GDE/Ni–Co. Stable operation was achieved for all MFC systems, confirming that waste buttermilk can support electroactive biofilm development. The GDE/Ni–Co configuration exhibited the highest performance, reaching a maximum power density of 25 mW·m⁻², compared to 22 mW·m⁻² and 17 mW·m⁻² for GDE/Cu–B and GDE/GDE, respectively. Coulombic efficiency ranged from 10.83% to 18.82%, depending on the electrode system. A cyclic performance decrease was observed, likely caused by membrane fouling and electrode surface blockage. The results indicate that waste buttermilk can be utilized for simultaneous waste treatment and energy recovery in MFC systems, although further optimization is required to improve long-term stability. Full article

Reverse osmosis (RO) membranes are widely applied in reuse facilities, but the management of RO concentrate remains a major sustainability challenge. Conventional brine disposal methods, such as deep well injection or evaporation ponds, are costly, energy intensive, and often ineffective at addressing the accumulation of contaminants of emerging concern (CEC) and per- and polyfluoroalkyl substances (PFAS). Bioelectrochemical systems, such as microbial fuel cells (MFCs), offer a promising pathway for sustainable brine organic load management by simultaneously reducing organic load and recovering energy. In this study, a pilot-scale MFC system (Aquacycl BETT^®, Escondido, CA, USA, unit, 12 modular reactors) was evaluated for treatment of RO concentrate produced by a combined ultrafiltration and closed-circuit reverse osmosis pilot train at the San Jacinto Valley Regional Water Reclamation Facility (San Jacinto, CA, USA). Operating with a 4-h hydraulic retention time, the MFC achieved an average chemical oxygen demand (COD) removal of 40% and biochemical oxygen demand (BOD₅) removal of 52%. Coulombic efficiency ranged from 2.8% to 15.5%, with an average energy recovery value of about 8.1 Wh per kg of COD removed. PFOS concentrations decreased by 36% across the MFC, and PFAS were not detected in the harvested anode biomass. The mechanism of PFOS attenuation (e.g., adsorption vs. transformation) was not directly evaluated. These findings highlight the potential of MFCs as a bioelectrochemical solution for sustainable water reuse RO brine management. Full article

Accelerated industrial development demands the search for efficient remediation technologies. Microbial fuel cells (MFCs) have the capacity to remediate organic matter-rich effluent by utilizing bacteria as biocatalysts capable of oxidizing organic material while simultaneously producing electricity. In this paper, a novel electrode is prepared through the carbonization of a tailored photopolymer with iron nanoparticles and carbon black (C-iNPCB) and its performance tested as an anode using dual chamber MFCs for the remediation of paper recycling plant effluent. Its efficiency is compared to a graphite rod (GR) and a carbon black-coated 3D-printed structure (3D-CB). The paper effluent containing chemical oxygen demand 5.0 g/L was used as feedstock in the MFCs. The GR anode (0.91 A/m²; 0.32 W/m²) and 3D-CB anode (0.88 A/m²; 0.30 W/m²) both achieved 56% COD removal, while the C-iNPCB-anode (5.71 A/m²; 3.75 W/m²) was the best performing, with over 80% COD removal. The photopolymerized doped anode exhibited superior performance in terms of both organic matter oxidation and conductivity, indicating higher effectiveness of this type of electrode in MFC technology. Full article