Xavier Alexis Walter, Carlo Santoro, John Greenman et al.

International Journal of Hydrogen Energy • 2020

Self-stratifying microbial fuel cells with three different electrodes sizes and volumes were operated in supercapacitive mode. As the electrodes size increased, the equivalent series resistance decreased, and the overall power was enhanced (small: ESR = 7.2 Ω and Pmax = 13 mW; large: ESR = 4.2 Ω and Pmax = 22 mW). Power density referred to cathode geometric surface area and displacement volume of the electrolyte in the reactors. With regards to the electrode wet surface area, the large size electrodes (L-MFC) displayed the lowest power density (460 μW cm−2) whilst the small and medium size electrodes (S-MFC, M-MFC) showed higher densities (668 μW cm−2 and 633 μW cm−2, respectively). With regard to the volumetric power densities the S-MFC, the M-MFC and the L-MFC had similar values (264 μW mL−1, 265 μW mL−1 and 249 μW cm−1, respectively). Power density normalised in terms of carbon weight utilised for fabricating MFC cathodes-electrodes showed high output for smaller electrode size MFC (5811 μW g−1-C- and 3270 μW g−1-C- for the S-MFC and L-MFC, respectively) due to the fact that electrodes were optimised for MFC operations and not supercapacitive discharges. Apparent capacitance was high at lower current pulses suggesting high faradaic contribution. The electrostatic contribution detected at high current pulses was quite low. The results obtained give rise to important possibilities of performance improvements by optimising the device design and the electrode fabrication.

Swati Das, Rishabh Raj, Sovik Das et al.

Frontiers in Sustainability • 2021

With the plausible depletion of fossil fuels in the near future and its associated environmental impacts, researchers have instigated the search for eco-friendly renewable bioenergy. Moreover, the increase in water pollution by industrial and anthropogenic activities is another alarming global concern. In this regard, the production of renewable and sustainable green bioenergy utilizing wastewater through microbial electrochemical technologies (METs) can alleviate these crucial problems by providing a sustainable solution to meet both the demands of energy and fresh water supply. Moreover, different bio-centered techniques such as nitrification and denitrification for nitrogen removal, and elimination of carcinogenic metals, pathogens, and organic components utilizing microbiota followed by toxicity sensing of different pollutants have been efficaciously exhibited through METs. However, inferior bioenergy production and recovery of low biomass yield in METs with high operational cost are noteworthy bottlenecks that hinder the scalability of this technology. Therefore, this review elaborates different physicochemical factors affecting the performance of METs, microbial interaction for the development of stable biofilm and so forth. Moreover, a broad overview on the production of bioenergy, along with the removal of pollutants from wastewater through different types of METs are also highlighted. Furthermore, the production of biofuels like ethanol, methanol, biodiesel, and gaseous fuel like bio-H 2 coupled with power generation using photosynthetic microorganisms via CO 2 sequestration through METs are also discussed. Additionally, recent developments with future scope for the field-scale implementation of METs along with their bottlenecks have been discussed, which has not been critically reviewed to date.

M H K Sangili, K Thangavel, B Alagirisamy et al.

Plant Science Today • 2025

Microbial fuel cells (MFCs) are an innovative, eco-friendly bioelectrochemical technology that simultaneously treats wastewater and generates renewable electricity by harnessing the metabolic activity of electroactive microbes. This review surveys advancements in MFC research from 2015 to 2025, highlighting key performance metrics, including power densities that typically range from 100 to 2000 mW/m² and chemical oxygen demand (COD) removal efficiencies between 60 % and 90 % across various organic substrates. MFCs generally consist of an anode chamber, where electrogenic bacteria oxidize organic matter, a cathode chamber that facilitates oxygen reduction and a proton exchange membrane (PEM) separating these compartments. Both pure cultures and mixed microbial communities play vital roles, with electrogenic microbes such as Geobacter sulfurreducens, Shewanella oneidensis and Pseudomonas aeruginosa being particularly important for electricity production. The technology effectively degrades a wide range of pollutants, including heavy metals (HMs), dyes, pharmaceuticals and nutrients, while utilizing waste streams such as domestic wastewater, industrial effluent, agricultural runoff and sludge to generate bioelectricity. Recent advances focus on improving electrode materials, exploring membrane alternatives and optimizing reactor designs to enhance electron transfer efficiency, increase power output and reduce costs. Despite challenges such as low power density, technical complexity, high material costs and scalability limitations, MFCs align with global sustainability goals, particularly the United Nations Sustainable Development Goals (SDGs) 6 and 7, offering potential for decentralized wastewater treatment and clean energy generation. Future research should prioritize interdisciplinary collaboration, policy support and industry engagement to bridge current gaps and advance the commercial deployment of MFC technology.

Thobeka Pearl Makhathini

Water • 2026

Microbial electrochemical technologies (METs) have emerged as promising approaches for coupling wastewater treatment with energy and resource recovery. Considerable progress has been made in elucidating extracellular electron transfer, biofilm behavior, and electrode development, enabling laboratory systems to achieve high removal efficiencies under controlled conditions. Despite these advances, implementation in real treatment infrastructure remains limited. This review evaluates the progression of METs from laboratory studies to pilot-scale and field applications within the wider landscape of electrochemical wastewater treatment. The effects of reactor setup, material strength, and operational difficulty on performance at different scales are emphasized. Evidence from recent pilots consistently shows reduced energy recovery, along with challenges such as internal resistance, mass-transfer constraints, fouling, and cathode degradation. Laboratory-scale MFC systems have reported peak power densities of up to 23,000 mW/m2 and normalized energy recoveries of up to 1.2 kWh/kg COD removed under optimized, controlled conditions; however, pilot-scale systems typically recover only 0.01–0.05 kWh/kg COD removed, representing one to two orders of magnitude below laboratory-reported values. This contrast underscores the persistent gap between controlled experimental performance and operational reality. Proposed solutions, such as modular scale-out, membrane simplification, and the use of low-cost, replaceable materials, are assessed based on their maturity and practical applicability. Techno-economic and life-cycle analyses indicate that component longevity and integration strategy are often more decisive than peak electrochemical output. METs are therefore most likely to provide near-term benefits in hybrid or niche applications rather than as standalone replacements. Advancement toward wider implementation will require standardized metrics, long-term demonstrations, and engineering designs prioritizing robustness and maintainability.

Khaya Pearlman Shabangu, Nhlanhla Mthembu, Manimagalay Chetty et al.

Fermentation • 2023

In this present study, the potential application of DCMFC for the treatment of three different sourced industrial wastewater streams: biorefinery, dairy and mixed streams was investigated. Operating conditions were optimised using the Box Behnken design in response surface methodology (RSM) with three validation experimental runs. The effect of process variables, i.e., HRT (48 h), catholyte dose (0.1 gmol/L) and electrode surface area (three carbon rods argumentation-m2) on the production of electricity as voltage yield (mV), power density (mW/m2), current density (mA/m2), Columbic efficiency (%) CE and Gibbs free energy correlation with the electromotive force of the DCMFC system. Experimental results obtained were a positive response towards the predictive values according to the DoE numerical optimisation sequence. At numerical optimum MFC conditions stated above, validation experimental responses of voltage yield by biorefinery wastewater were 645.2 mV, mixed wastewater was 549 mV, and dairy wastewater was 358 mV maximum yields. The power densities and current densities were attained, for biorefinery, mixed wastewater and dairy wastewater sources respectively as; 62 mW/m2, 50 mW/m2 and 27.2 mW/m2, then current densities of 50 mA/m2, 44,008 mA/m2 and 18 mA/m2. The coulombic efficiencies of 0.34%, 0.75% and 0.22%, respectively, were achieved. The validation of predicted optimum operating conditions was successfully attained, especially through the biorefinery wastewater organic substrate. This article articulates that it is highly imperative to choose the most suitable wastewater source as the viable electron donor towards scaling up and maximising the efficiency of generating electricity in the double chamber microbial fuel cell (DCMFC). Moreover, the findings of the current study demonstrate that the DCMFC can be further upscaled through a series connection in a fed-batch mode of operation using a well-designed and simulated process control system that has been computationally designed and modelled using first order MFC model bioenergy generating models MATLAB Simulink and Simscape electrical software. These findings of the simulations were successful and illustrated that an MFC power output can be successfully stepped to be a viable bio-electrochemical technology for both industrial wastewater (IWW) treatment and simultaneous sustainable power generation.

Shilpa Padmanabhan, Anbazhagi Muthukumar, M. Muthuchamy

Green Energy and Environmental Technology • 2026

Microbial fuel cells (MFCs) are a sustainable method of treating wastewater and producing electricity simultaneously. The current study utilizes graphite, aluminium, stainless steel, galvanized iron, and brass electrodes to assess the performance of MFCs using a variety of real-world wastewater samples, including those from slaughterhouses, fish markets, and dairy farms. The wastewater from dairy plants loaded into MFCs with graphite electrodes performed better than other metal-based electrodes, with an open-circuit voltage of 289 mV, a power density of 412 W/m 2 , and a current density of 1,450 mA/m 2 . The results of other reactors varied: Fish market wastewater with graphite electrode (270 mV, 87.78 mW/m 2 , 325.13 mA/m 2 ), slaughterhouse wastewater (SWMFC) with graphite electrode (4.05 mV, 279.19 mW/m 2 , 1080 mA/m 2 ), and SWMFC with brass electrode (4.23 mV, 1211 mW/m 2 , 460 mA/m 2 ). When considering chemical oxygen demand, SWMFC achieved maximum removal efficiency of 90% for graphite and 88% for brass. Additionally, the electrogenic activity of Raoultella ornithinolytica and Comamonas testosteroni in MFCs that treat wastewater from slaughterhouse sources was assessed. Graphite electrodes coated with R. ornithinolytica generated more power and current, while brass electrodes coated with C. testosteroni generated higher voltage. To guide future scale-up processes and component optimization, these results highlight the critical roles that microbial populations and electrode material play in MFC efficiency.

Khaya Pearlman Shabangu, Maggie Chetty, Babatunde Femi Bakare

Bioengineering • 2025

This study evaluates the potential of biorefinery and dairy wastewater as substrates for electricity generation in double chamber Microbial Fuel Cells (DCMFC), focusing on their microbial taxonomy and electrochemical viability. Taxonomic analysis using 16S/18S rDNA-targeted DGGE and high-throughput sequencing identified Proteobacteria as dominant in biorefinery biomass, followed by Firmicutes and Bacteriodota. In dairy biomass, Lactobacillus (77.36%) and Clostridium (15.70%) were most prevalent. Biorefinery wastewater exhibited the highest bioelectrochemical viability due to its superior electrical conductivity and salinity, achieving a voltage yield of 65 mV, compared to 75.2 mV from mixed substrates and 1.7 mV from dairy wastewater. Elevated phosphate levels in dairy wastewater inhibited bioelectrochemical processes. This study recommends Biorefinery wastewater as the most suitable purely organic substrate for efficient bioelectricity generation and scaling up of MFCs, emphasising the importance of substrate selection for optimal energy output for practical and commercial viability.

Yanzhen Fan, Anthony Janicek, Hong Liu

The European Chemistry and Biotechnology Journal • 2024

The voltage output of a single MFC is normally less than 0.8 V, often less than 0.3 V at maximum power output, which greatly limits the application of MFCs. When MFCs are scaled up, however, increasing reactor size has typically resulted in decreased power density. In this study, we developed a novel MFC configuration that contains multiple cloth electrode assemblies in which the MFCs were internally connected in series (iCiS-MFC). The iCiS-MFC, equivalent to 3 CEA-MFCs, produced a high voltage output over 1.8 V and a maximum power density of 3.5 W m-2 using carbon cloth cathodes containing activated carbon as the catalyst. This power density is 6% higher than that reported for a similar smaller CEA-MFC, indicating that power can be maintained during scale-up with a greater than 33-fold increase in total cathode surface area and greater than 20-fold increase in reactor volume. High stability was also demonstrated based on the performance of the iCiS-MFC over a period of one year of operation. The high power and stability is likely due, in part, to a more efficient means of current collection through the internal series connection, which also avoids the use of expensive current collectors. These results clearly demonstrate the great potential of this MFC design for further scaling-up.

Bruce Logan, Shaoan Cheng, Valerie Watson et al.

Environmental Science & Technology • 2007

To efficiently generate electricity in microbial fuel cells, the surface area of the anode must be maximized to support biofilm growth while minimizing total reactor volume. Graphite fiber brush electrodes provide high surface areas and porosities. A brush electrode placed in a single-chamber air-cathode MFC produced a maximum power density of 1430 mW/m² (73 W/m³) with ammonia-treated brush anodes and acetate substrate, exceeding previous reports for MFC power densities.

P. S. Kamble, Devanshu Kodhey, Rahul A. Bhende et al.

International Journal of Advanced Research in Science Communication and Technology • 2025

Dairy wastewater presents a significant environmental challenge due to its high concentrations of organic matter, nutrients, and suspended solids. Conventional treatment methods, while effective in pollutant removal, often involve energy-intensive processes that generate excess sludge and require substantial operational costs. With the growing demand for sustainable and energy-efficient technologies, integrating constructed wetlands (CWs) with microbial fuel cells (MFCs) emerges as a promising solution. The growing demand for sustainable wastewater treatment technologies has led to the exploration of hybrid systems that combine ecological treatment with energy recovery. Dairy wastewater, characterized by high organic load, nutrients, and suspended solids, presents a significant environmental challenge if discharged untreated. This study investigates an integrated system that combines a constructed wetland (CW) with a microbial fuel cell (MFC) to simultaneously treat dairy wastewater and generate electricity. The constructed wetland acts as a biofilter to reduce pollutants, while the microbial fuel cell harnesses the metabolic activity of electrogenic bacteria to convert organic matter into electrical energy. This study investigates the performance of a hybrid CW-MFC system in simultaneously treating dairy wastewater and generating electricity. The constructed wetland acts as a natural biofilter, facilitating the removal of contaminants through physical, chemical, and biological mechanisms, while the microbial fuel cell component utilizes electrogenic bacteria to oxidize organic matter and convert chemical energy into electrical energy. Experimental analysis was conducted using synthetic and real dairy wastewater under varying operational conditions, including different hydraulic retention times, electrode materials, and plant species.The results demonstrate that the CW-MFC system effectively reduces pollutants such as BOD, COD, and nutrients while generating a measurable amount of electricity. The hybrid system not only enhances wastewater treatment efficiency but also contributes to renewable energy generation. This integrated approach offers a cost-effective, environmentally friendly alternative to conventional wastewater treatment methods, with significant potential for scalability and rural application

Monolina Sarkar

Journal of Hazardous Materials Advances • 2023

The existence of micropollutants in wastewater is one of the most challenging environmental issues in the world today. Due to their high stability and resistance to physicochemical and biological degradation, pollutants like hormonally active substances, pesticides, industrial chemicals, pharmaceuticals, personal care products, doping substances, and narcotics among others are difficult to remove in wastewater treatment plants (WWTPs). A potential technology for treating pollutants is photocatalytic biodegradation. The advancements in light-responsive biodegradation technologies—namely, intimately coupled photocatalysis and biodegradation (ICPB), microbial fuel cells (MFCs), and photobiocatalysis are highlighted in this work. The article identifies opportunities for refining current methodologies. It aims to provide a perspective for future research devoted to assessing and improving pollutant removal.

Marwa M. Jiad, Ali H. Abbar, Zaid H. Jabbar

Environmental Technology Reviews • 2025

Abdollah Dargahi, Reza Shokoohi, Ghorban Asgari et al.

RSC Advances • 2021

Application for real wastewater, kinetics modelling, effect of operating parameters on removal of 2,4-D using MBBR–3DE processes, improvement of biodegradability and Identification of herbicide-degrading microorganisms.

Tope Oyebade, Oluwatoyin Adekoya

GSC Biological and Pharmaceutical Sciences • 2022

Pharmaceutical residues have emerged as persistent micropollutants in aquatic ecosystems, posing ecological, toxicological, and public health challenges due to their bioaccumulation and resistance to conventional wastewater treatment. Advanced oxidation processes (AOPs) have gained prominence for degrading such complex compounds, yet individual techniques often suffer from operational inefficiencies, incomplete mineralization, or high energy demands. This study explores the integration of electrochemical oxidation (EO) and photocatalysis as a synergistic treatment pathway capable of addressing these limitations under variable environmental conditions. The hybrid system combines the anodic generation of reactive oxygen species (•OH, O₂•–) with photoexcited semiconductor catalysts such as TiO₂ or doped ZnO, enabling simultaneous oxidation and photodegradation of pharmaceutical contaminants. The integration enhances electron–hole separation, improves mass transfer, and extends the oxidative potential beyond either process alone. Experimental simulations under varying pH, temperature, and light intensity demonstrate that the combined EO–photocatalytic process achieves higher degradation efficiency and total organic carbon (TOC) removal than standalone systems. Mechanistic analysis reveals that environmental conditions critically influence radical formation kinetics, electrode stability, and catalyst photoreactivity, thereby dictating the overall mineralization rate. Furthermore, the process exhibits resilience against matrix interferences such as chloride, bicarbonate, and natural organic matter. The study concludes that optimized hybrid EO–photocatalytic configurations represent a scalable and sustainable route for removing persistent pharmaceuticals from wastewater, contributing to circular water management and pollution mitigation. Future work should focus on energy recovery, reactor design optimization, and real effluent validation to ensure full-scale applicability in diverse climatic contexts.

Chengzhi Wang, Yi Xing, Kangning Zhang et al.

Journal of Power Sources • 2023

A photocathode-microbial electrochemical coupling system (PC-MFC) using black phosphorus-doped titanium dioxide nanobelt (BP/TB) as a photocatalyst is constructed for the degradation of hydroxychloroquine (HCQ, used to treat COVID-19). The degradation efficiency of HCQ (100 mg/L) in coupling system is 73.7% within 8 h, higher than that of photocatalysis (69.5%), MFC (25.6%), and adsorption (9.6%). The photocathode coupling facilitates subsequent bioelectric treatment, resulting in complete degradation of HCQ (100 mg/L) within 96 h in PC-MFC, much higher than in MFC (51.1%). Illumination of PC-MFC significantly increases the cathodic abundance of Pseudomonadales ord. (from 1.83% to 66.30%), accumulates biomass, improves the electrochemical behaviors of photocathode and bioanode, and finally increases the maximum power from 241 to 280 mW/m 2 . The electron transfer pathways depende on nicotinamide adenine dinucleotide dehydrogenase , succinate dehydrogenase and terminal oxidase . The coupled system enhances the dechlorination reduction of HCQ and reduces the biotoxicity of its degradation pathway. PC-MFC represents a new strategy for the treatment and energy recovery of refractory organic compounds in wastewater. • A single-chamber microbial fuel cell with a coupled photocathode was constructed. • The system increased the removal of hydroxychloroquine (HCQ) by 52.0%. • The system facilitated electrochemical behaviors and electricity production. • Photocathode increased the abundance of Pseudomonadales ord. and enriched biomass. • The photocathode enhanced the dechlorination and reduced the toxicity of HCQ.

Nuno Jorge, Ana R. Teixeira, Marco S. Lucas et al.

Environmental Research • 2025

Xinying Zhang, Yan Wu, Gao Xiao et al.

PLoS ONE • 2017

Azo dyes are very resistant to light-induced fading and biodegradation. Existing advanced oxidative pre-treatment methods based on the generation of non-selective radicals cannot efficiently remove these dyes from wastewater streams, and post-treatment oxidative dye removal is problematic because it may leave many byproducts with unknown toxicity profiles in the outgoing water, or cause expensive complete mineralization. These problems could potentially be overcome by combining photocatalysis and biodegradation. A novel visible-light-responsive hybrid dye removal agent featuring both photocatalysts (g-C3N4-P25) and photosynthetic bacteria encapsulated in calcium alginate beads was prepared by self-assembly. This system achieved a removal efficiency of 94% for the dye reactive brilliant red X-3b and also reduced the COD of synthetic wastewater samples by 84.7%, successfully decolorized synthetic dye-contaminated wastewater and reduced its COD, demonstrating the advantages of combining photocatalysis and biocatalysis for wastewater purification. The composite apparently degrades X-3b by initially converting the dye into aniline and phenol derivatives whose aryl moieties are then attacked by free radicals to form alkyl derivatives, preventing the accumulation of aromatic hydrocarbons that might suppress microbial activity. These alkyl intermediates are finally degraded by the photosynthetic bacteria.

Chun Zhao, Weijie Yang, Qianyong Zhang et al.

Frontiers in Science and Engineering • 2025

This study addresses the problems of high energy consumption, high cost, and incomplete removal existing in traditional treatment methods for oily wastewater from ships, and proposes and constructs a Photocatalytically-assisted Microbial Fuel Cells (PMFC) device for efficient and green treatment. The device couples photocatalysis with Microbial Fuel Cell (MFC) technology, utilizing ⋅OH and ⋅O2− generated by semiconductor photocatalysts under illumination to synergistically degrade oil pollutants with microbial metabolism. Specifically, pine cone shell biochar (PBC) modified by high-temperature carbonization (350°C) and H₂O₂ oxidation (HPBC) is used as the anode substrate, which significantly improves its hydrophilicity (contact angle reduced to 44.637°) to facilitate the attachment of photocatalysts and microorganisms. Then, a TiO₂/g-C₃N₄ heterojunction photocatalyst (TiO₂/g-C₃N₄@HPBC) is loaded to construct a composite photoanode. A two-chamber PMFC reactor is built, using an emulsified diesel solution prepared with an inorganic salt medium as the anolyte, a potassium ferricyanide solution as the catholyte, and a composite microbial community as the anode microorganisms. The results show that the maximum output voltage of 0.6389V and oil degradation rate of 76.34% of PMFC under illumination are significantly higher than the maximum output voltage of 0.5832V and oil degradation rate of 71.72% under dark conditions, confirming that the photocatalytic effect effectively improves the power generation performance and pollutant degradation efficiency of the system. The PMFC device provides an energy-saving and efficient potential solution for the treatment of oily wastewater from ships.

Rajanandini Meher, M. Matheshwaran, Naresh Kumar Sharma

Environmental Technology • 2025

The growing demand for surgical cotton in the healthcare sector has led to increased production in southern Tamil Nadu, generating effluents that pose environmental risks due to their chemical composition. Unlike conventional textile effluents, surgical cotton processing wastewater is distinct for its lack of colour additive, but it exhibits high chemical oxygen demand (COD) and contains significant inorganic pollutants, necessitating tailored treatment strategies. Despite extensive research on textile wastewater, effective solutions for surgical cotton effluents remain underexplored. This research bridges this gap by exploring a novel synergic method, algae-bacterial symbiosis combined with photocatalytic degradation for real surgical cotton effluent, in order to ultimately improve the removal ability of the contaminants. The general aim was to study the performance of three continuous reactor, a photocatalytic reactor, a biological rector and coupled biological-photocatalytic (CBPCR) reactor in the degradation of surgical cotton processing effluent during 30 days. The treatment efficacy was measured by observing the removal rates of inorganic nutrient, COD, and microbial growth. It was concluded that the CBPCR system successfully removed nitrate, phosphate, ammonia, and COD by 90%, 87%, 75%, and 93% respectively. In particular, the system fostered vigorous growth of both microalgae and bacteria, as indicated by a total chlorophyll concentration of 20.1 ± 0.91 mg/L and a dry cell weight of 1.81 ± 0.09 g/L. This paper shows the feasibility of the CBPCR system as a green, sustainable strategy for the treatment of surgical cotton effluent and as such fills a gap in current practice of industrial wastewater treatment.

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