Reduced graphene oxide and biofilms as cathode catalysts to enhance energy and metal recovery in microbial fuel cell

Revolutionizing dairy waste: emerging solutions in conjunction with microbial engineering

The dairy industry is grappling with significant challenges in managing effluent due to environmental concerns and stringent regulatory demands, necessitating innovative solutions. The paper investigates how microbial engineering is transforming the treatment of dairy wastewater, offering advanced methods to minimize environmental impact and enhance sustainability. It delves into the current challenges faced by the dairy industry, such as regulatory compliance and the limitations of traditional treatment technologies, and introduces microbial engineering as a promising solution for effluent management. Microbial engineering leverages genetic engineering techniques and microorganisms to enhance the efficiency of treatment processes like bioaugmentation and bioremediation. The environmental and economic benefits of microbial engineering, highlighting its potential to reduce pollution and lower operational costs for the dairy industry. The specific figures can vary based on factors like farm size and location, studies suggest that microbial engineering can reduce wastewater pollution by up to 50% and nutrient runoff by 30%. It also identifies key challenges and there are still areas including strains for specific pollutants (drugs, hormones), enhance degradation pathways, and increase microbes' stability (stress tolerance, long-term viability) that require further innovation to maximize its benefits. Through case studies and success stories, the paper demonstrates practical applications of microbial engineering in managing dairy effluent, illustrating how it can revolutionize industrial practices for a more sustainable future.

Material modification of electrodes in microbial electrochemical system to enhance electrons utilization on the electrode and its impact on microorganisms

Previous research has established a MES embedding a microbial electrode to facilitate the degradation of antibiotics in water. We modified microbial electrodes in the MES with PEDOT and rGO to enhance electron utilization on electrodes and to further promote antibiotic degradation. Density functional theory calculations on the SMX molecule indicated that the C4-S8 and S8-N27 bonds are the most susceptible to electron attack. The introduction of various functional groups and multivalent elements enhanced the electrodes' capacitance and electron mediation capabilities. This led to enhance both electron utilization on the electrodes and the removal efficiency of SMX. After 120 h, the degradation efficiency of SMX by PEDOT and rGO-modified electrodes increased by 45.47 % and 25.19 %, respectively, compared to unmodified electrodes. The relative abundance of sulfate-reducing and denitrifying bacteria significantly increased in PEDOT and rGO-modified electrodes, while the abundance of nitrifying bacteria and potential antibiotic resistance gene host microbes significantly decreased. The impact of PEDOT modification positively influenced microbial Cellular Processes, including cell growth, death, and motility. This study provides insights into the mechanisms of direct electron involvement in antibiotic degradation steps in microbial electrochemistry, and provides a possible path for improved strategies in antibiotic degradation and sustainable environmental remediation.

Boron-doped reduced graphene oxide as an efficient cathode in microbial fuel cells for biological toxicity detection

Electrodes with superior stability and sensitivity are highly desirable in advancing the toxicity detection efficiency of microbial fuel cells (MFCs). Herein, boron-doped reduced graphene oxide (B-rGO) was synthesized and utilized as an efficient cathode candidate in an MFCs system for sensitive sodium dodecylbenzene sulfonate (SDBS) detection. Boron doping introduces additional defects and improves the dispersibility and oxygen permeability, thereby enhancing the oxygen reduction reaction (ORR) efficiency. The B-rGO-based cathode has demonstrated significantly improved output voltage and power density, marking improvements of 75 % and 58 % over their undoped counterparts, respectively. Furthermore, it also exhibited remarkable linear sensitivity to SDBS concentrations across a broad range (0.2-15 mg/L). Notably, the cathode maintained excellent stability within the test range and showed significant reversibility for SDBS concentrations between 0.2 and 3 mg/L. The highly sensitive and stable B-rGO-based cathode is inspiring for developing more practical and cost-effective toxicant sensing devices.

Nitrogen-doped Zn/Fe@PCN derived from metal-organic frameworks activating persulfate to efficiently degrade rhodamine B

The Zn/Fe@N-doped porous graphitic carbon catalyst (Zn/Fe@PCN) was successfully produced through one-step pyrolysis of g-C3N4 and Zn/Fe-MOF and was used for the activation of persulfate (PS) for the degradation of RhB. The Zn/Fe@PCN/PS system was able to degrade 95.92% of RhB in 30 min at a rate of 0.6453 min-1 when RhB was concentrated at 50 mg L-1. The efficient degradation of RhB is primarily realized through the synergistic activation of PS by Zn, Fe, and N to produce reactive oxygen species 1O2, [Formula: see text], [Formula: see text], and ·OH. Zn0/Fe0 in Zn/Fe@PCN forms a galvanic cell with carbon to release electrons to join in the activation of PS. The doping of Zn not only provides sufficient electrons for the activation of PS but also promotes the effective reduction of Fe2+ and thus the Fe2+/Fe3+ cycle. The N doping accelerates the electron transfer during the reaction progress.

Graphene-based RRAM devices for neural computing

Resistive random access memory is very well known for its potential application in in-memory and neural computing. However, they often have different types of device-to-device and cycle-to-cycle variability. This makes it harder to build highly accurate crossbar arrays. Traditional RRAM designs make use of various filament-based oxide materials for creating a channel that is sandwiched between two electrodes to form a two-terminal structure. They are often subjected to mechanical and electrical stress over repeated read-and-write cycles. The behavior of these devices often varies in practice across wafer arrays over these stresses when fabricated. The use of emerging 2D materials is explored to improve electrical endurance, long retention time, high switching speed, and fewer power losses. This study provides an in-depth exploration of neuro-memristive computing and its potential applications, focusing specifically on the utilization of graphene and 2D materials in RRAM for neural computing. The study presents a comprehensive analysis of the structural and design aspects of graphene-based RRAM, along with a thorough examination of commercially available RRAM models and their fabrication techniques. Furthermore, the study investigates the diverse range of applications that can benefit from graphene-based RRAM devices.

Microbial Biofilms for Environmental Bioremediation of Heavy Metals: a Review

Heavy metal pollution caused due to various industrial and mining activities poses a serious threat to all forms of life in the environment because of the persistence and toxicity of metal ions. Microbial-mediated bioremediation including microbial biofilms has received significant attention as a sustainable tool for heavy metal removal as it is considered safe, effective, and feasible. The biofilm matrix is dynamic, having microbial cells as major components with constantly changing and evolving microenvironments. This review summarizes the bioremediation potential of bacterial biofilms for different metal ions. The composition and mechanism of biofilm formation along with interspecies communication among biofilm-forming bacteria have been discussed. The interaction of biofilm-associated microbes with heavy metals takes place through a variety of mechanisms. These include biosorption and bioaccumulation in which the microbes interact with the metal ions leading to their conversion from a highly toxic form to a less toxic form. Such interactions are facilitated via the negative charge of the extracellular polymeric substances on the surface of the biofilm with the positive charge of the metal ions and the high cell densities and high concentrations of cell-cell signaling molecules within the biofilm matrix. Furthermore, the impact of the anodic and cathodic redox potentials in a bioelectrochemical system (BES) for the reduction, removal, and recovery of numerous heavy metal species provides an interesting insight into the bacterial biofilm-mediated bioelectroremediation process. The review concludes that biofilm-linked bioremediation is a viable option for the mitigation of heavy metal pollution in water and ecosystem recovery.

Graphene and biochar-based cathode catalysts for microbial fuel cell: Performance evaluation, economic comparison, environmental and future perspectives

Microbial fuel cells (MFCs) have been the prime focus of research in recent years because of their distinctive feature of concomitantly treating and producing electricity from wastewater. Nevertheless, the electrical performance of MFCs is hindered by a protracted oxygen reduction reaction (ORR), and often a catalyst is required to boost the cathodic reactions. Conventional transition metals-based catalysts are expensive and infeasible for field-scale usage. In this regard, carbon-based electrocatalysts like waste-derived biochar and graphene are used to enhance the commercialisation prospects of MFC technology. These carbon-catalysts possess unique properties like superior electrocatalytic activity, higher surface area, and high porosity conducive to ORR. Theoretically, graphene-based cathode catalysts yield superior results than a biochar-derived catalyst, though at a higher cost. In contrast, the synthesis of waste-extracted biochar is economical; however, its ability to catalyse ORR is debatable. Therefore, this review aims to make a side-by-side techno-economic assessment of biochar and graphene-based cathode catalyst used in MFC to predict the relative performance and typical cost of power recovery. Additionally, the life cycle analysis of the graphene and biochar-based materials has been briefly discussed to comprehend the associated environmental impacts and overall sustainability of these carbo-catalysts.

Simultaneous treatment of chromium-containing wastewater and electricity generation using a plant cathode-sediment microbial fuel cell: investigation of associated mechanism and influencing factors

A novel plant cathode-sediment microbial fuel cell (P-SMFC) was constructed to treat Cr-containing wastewater, and the effects of the plants used, initial concentrations of Cr(VI) employed, and the external resistance on the treatment of wastewater and generation of electricity were investigated. The results showed that the system achieved the best performance when Acorus calamus was the cathode plant, the external resistance was 2000 Ω, and the initial Cr (VI) concentration of the overlying water of is 230 mg/L. A maximum power density of 40.16 mW/m² was reached, and Cr (VI) and COD removal efficiencies in the overlying water were 99.94% and 98.21%, respectively. The closed-circuit installation promoted the attachment of many microorganisms to the cathode, anode and sediment, increased species abundance, and reduced species diversity. The P-SMFC is inexpensive to construct, it consumes no energy, and it can generate bioelectricity; it thus has great application development value as a chromium-containing wastewater treatment method.

Bioelectrochemical systems-based metal removal and recovery from wastewater and polluted soil: Key factors, development, and perspective

Bioelectrochemical systems (BES) are considered efficient and sustainable technologies for bioenergy generation and simultaneously removal/recovery metal (loid)s from soil and wastewater. However, several current challenges of BES-based metal removal and recovery, especially concentrating target metals from complex contaminated wastewater or soil and their economic feasibility of engineering applications. This review summarized the applications of BES-based metal removal and recovery systems from wastewater and contaminated soil and evaluated their performances on electricity generation and metal removal/recovery efficiency. In addition, an in depth review of several key parameters (BES configurations, electrodes, catalysts, metal concentration, pH value, substrate categories, etc.) of BES-based metal removal and recovery was carried out to facilitate a deep understanding of their development and to suggest strategies for scaling up their specific application fields. Finally, the future intervention on multifunctional BES to improve their performances of mental removal and recovery were revealed.

Microbial fuel cells for mineralization and decolorization of azo dyes: Recent advances in design and materials

Microbial fuel cells (MFCs) exhibit tremendous potential in the sustainable management of dye wastewater via degrading azo dyes while generating electricity. The past decade has witnessed advances in MFC configurations and materials; however, comprehensive analyses of design and material and its association with dye degradation and electricity generation are required for their industrial application. MFC models with high efficiency of dye decolorization (96-100%) and a wide variation in power generation (29.4-940 mW/m²) have been reported. However, only 28 out of 104 studies analyzed dye mineralization - a prerequisite to obviate dye toxicity. Consequently, the current review aims to provide an in-depth analysis of MFCs potential in dye degradation and mineralization and evaluates materials and designs as crucial factors. Also, structural and operation parameters critical to large-scale applicability and complete mineralization of azo dye were evaluated. Choice of materials, i.e., bacteria, anode, cathode, cathode catalyst, membrane, and substrate and their effects on power density and dye decolorization efficiency presented in review will help in economic feasibility and MFCs scalability to develop a self-sustainable solution for treating azo dye wastewater.

A review on graphene / graphene oxide supported electrodes for microbial fuel cell applications: Challenges and prospects

Microbial Fuel Cell (MFC) has gained great interest as an alternative green technology for bioenergy generation along with reduced sludge production, nutrient recovery, removal of COD and color, etc. during wastewater treatment. However, the MFC has several challenges for real-time applications due to less power output and high ohmic resistance and fabrication (electrode and membrane) cost. Several kinds of research have been carried out to increase energy production by reducing various losses associated with electrodes in the MFC. Though, carbonaceous electrodes (carbon and graphite) are the key materials for the anode and cathode side, since these have a higher surface area, good biocompatibility, low cost, and good mechanical strength. Graphene or graphene oxide-based nanocomposite can be an ideal substitute for electrode modifications and an alternative for an expensive anode and cathode catalyst in MFC. Graphene oxide synthesis from waste material such as waste biomass, agricultural, plastic waste, etc. is added advantages of minimizing the cost of the electrodes. But, the synthesis of graphene is quite expensive and has limitations in economic feasibility for bioelectricity production in MFC. Hence, the present review deals with the anode and cathode electrode modification with graphene-based nanocomposites, synthesis of graphene/graphene oxide from various raw materials, and its application in MFC. The current challenges and future outlook on graphene-based composites on MFC performance are also discussed.

Nanoadsorbants for the Removal of Heavy Metals from Contaminated Water: Current Scenario and Future Directions

Heavy metal pollution of aquatic media has grown significantly over the past few decades. Therefore, a number of physical, chemical, biological, and electrochemical technologies are being employed to tackle this problem. However, they possess various inescapable shortcomings curbing their utilization at a commercial scale. In this regard, nanotechnology has provided efficient and cost-effective solutions for the extraction of heavy metals from water. This review will provide a detailed overview on the efficiency and applicability of various adsorbents, i.e., carbon nanotubes, graphene, silica, zero-valent iron, and magnetic nanoparticles for scavenging metallic ions. These nanoparticles exhibit potential to be used in extracting a variety of toxic metals. Recently, nanomaterial-assisted bioelectrochemical removal of heavy metals has also emerged. To that end, various nanoparticle-based electrodes are being developed, offering more efficient, cost-effective, ecofriendly, and sustainable options. In addition, the promising perspectives of nanomaterials in environmental applications are also discussed in this paper and potential directions for future works are suggested.

Miscanthus as a carbon precursor for graphene oxide: A possibility influenced by pyrolysis temperature

This study investigates the potential of producing graphene oxide (GO) from biomass via green (comparatively) processing and the impact of graphitization temperature on GO quality. Our findings show that it is possible to convert biomass into highly pyrolytic biochar, followed by shear exfoliation to produce few-layer GO. However, pyrolysis temperature is key in ensuring that the biochar is suited for effective exfoliation. Low temperatures (<1000 °C) would preserve undesirable heterogenous, complex cellular structure of biomass whilst excessive temperatures (≥1300 °C) result in uncontrolled melting, coalescence and loss of functional groups. Results show 1200 °C to be the optimum graphitization temperature for miscanthus, where the resultant biochar is highly aromatic with sufficient functional groups to weaken van der Waals forces, thus facilitating exfoliation to form 6-layer GO with specific surface area of 545.3 m²g^-1. This study demonstrates the potential of producing high quality, fit-for-purpose graphene materials from renewable sources.

Surface Modification of Reduced Graphene Oxide Beads: Integrating Efficient Endotoxin Adsorption and Improved Blood Compatibility

As a pathogenic toxin, endotoxins are the culprit for endotoxemia and can be generally removed from the blood by hemoperfusion. Reduced graphene oxide (rGO) is a promising endotoxin sorbent for hemoperfusion owing to its excellent adsorption capacity, but it has the side effect of nonspecific adsorption and low blood compatibility. Polymyxin B (PMB) acts as an organic affinity ligand that can specifically bind endotoxins. As a natural anticoagulant, heparin (Hep) can reduce the risk of coagulation and improve the blood compatibility of materials. Herein, an rGO bead adsorbent was prepared by coupling with PMB and Hep and used for endotoxin adsorption; in this, polydopamine (pDA) served as an active coating for immobilization of PMB and further coupling with Hep. The physicochemical characteristics indicated that PMB and Hep were successfully immobilized on rGO beads with a hierarchical pore structure. PMB endowed rGO beads with higher adsorption capacity (143.84 ± 3.28 EU/mg) and good adsorption selectivity for endotoxins. Hep significantly improved the blood compatibility of rGO beads. These modified rGO beads also achieved good adsorption capacity and adsorption selectivity for endotoxins in plasma, serum, or blood. Therefore, rGO/pDA/PMB/Hep beads are potential adsorbents for endotoxins in hemoperfusion.

From Microorganism-Based Amperometric Biosensors towards Microbial Fuel Cells

This review focuses on the overview of microbial amperometric biosensors and microbial biofuel cells (MFC) and shows how very similar principles are applied for the design of both types of these bioelectronics-based devices. Most microorganism-based amperometric biosensors show poor specificity, but this drawback can be exploited in the design of microbial biofuel cells because this enables them to consume wider range of chemical fuels. The efficiency of the charge transfer is among the most challenging and critical issues during the development of any kind of biofuel cell. In most cases, particular redox mediators and nanomaterials are applied for the facilitation of charge transfer from applied biomaterials towards biofuel cell electrodes. Some improvements in charge transfer efficiency can be achieved by the application of conducting polymers (CPs), which can be used for the immobilization of enzymes and in some particular cases even for the facilitation of charge transfer. In this review, charge transfer pathways and mechanisms, which are suitable for the design of biosensors and in biofuel cells, are discussed. Modification methods of the cell-wall/membrane by conducting polymers in order to enhance charge transfer efficiency of microorganisms, which can be potentially applied in the design of microbial biofuel cells, are outlined. The biocompatibility-related aspects of conducting polymers with microorganisms are summarized.

A nickel oxide-decorated in situ grown 3-D graphitic forest engrained carbon foam electrode for microbial fuel cells

Carbon foam was used as a substrate for NiO and growing carbon nanofibers. The synthesized NiO-CNF-CF electrode was successfully used as an efficient electrode for a microbial fuel cell.

Boosting oxygen reduction and permeability properties of doped iron-porphyrin membrane cathode in microbial fuel cells

To achieve a membrane cathode with excellent performance, iron-porphyrin (Fe(por)) was doped to boost the catalytic and permeability properties in microbial fuel cell (MFC). The membrane cathode with the optimal 0.05 g of Fe(por) (denoted as Fe(por)-0.05) had the highest current density of 10.3 A m^-2 and the lowest charge transfer resistance of 12.6 ± 0.3 Ω. The ring-disk electrode (RDE) results further proved that the oxygen reduction reaction (ORR) occurred on the Fe(por)-0.05 through a direct four-electron transfer pathway. Moreover, the membrane cathode performed better permeability properties under electric filed and the Fe(por)-0.05 + E (E was electric field) obtained the lowest flux attenuation ratio of 14.1 ± 0.2%, which was related to its superior hydrophilicity and strong electrostatic repulsion force. Iron-porphyrin can simultaneously enhance the ORR activity and permeability of membrane cathode, providing a new direction for the practical application in MFCs.

Anode Modification as an Alternative Approach to Improve Electricity Generation in Microbial Fuel Cells

Sustainable production of electricity from renewable sources by microorganisms is considered an attractive alternative to energy production from fossil fuels. In recent years, research on microbial fuel cells (MFCs) technology for electricity production has increased. However, there are problems with up-scaling MFCs due to the fairly low power output and high operational costs. One of the approaches to improving energy generation in MFCs is by modifying the existing anode materials to provide more electrochemically active sites and improve the adhesion of microorganisms. The aim of this review is to present the effect of anode modification with carbon compounds, metallic nanomaterials, and polymers and the effect that these modifications have on the structure of the microbiological community inhabiting the anode surface. This review summarizes the advantages and disadvantages of individual materials as well as possibilities for using them for environmentally friendly production of electricity in MFCs.

An efficient system for electro-Fenton oxidation of pesticide by a reduced graphene oxide-aminopyrazine@3DNi foam gas diffusion electrode

A stable rGO-AmPyraz@3DNiF gas diffusion electrode was prepared via modification of 3D nickel foam (3D-NiF) with aminopyrazine functionalized reduced graphene oxide (rGO-AmPyraz) for the electro Fenton (EF) process. The generation capacity of H₂O₂ and OH radicals by this electrode was assessed relative to 3DNiF and rGO-AmPyraz@indium tin oxide (ITO) electrodes and with/without a coated Fe₃O₄ plate. The rGO-AmPyraz@3DNiF electrode showed the maximum production of these radicals at 2.2 mmol h^-1 and 410 μmol h^-1, respectively (pH 3) with the least leaching of Ni²⁺ such as < 0.5 mg L^-1 even after 5 cycles (e.g., relative to 3DNiF (24 mg L^-1). Such control on Ni ion leaching was effective all across the tested pH from 3 to 8.5. Its H₂O₂ generation capacity was far higher than that of the nanocarbon supported on commercially available ITO conductive glass. The mineralization of dichlorvos (at initial concentration: 50 mg L^-1) was confirmed with its complete degradation as the concentrations of the end products (e.g., free Cl^-1 (5.36 mg L^-1) and phosphate (12.89 mg L^-1)) were in good agreement with their stoichiometric concentration in dichlorvos. As such, the proposed system can be recommended as an effective electrode to replace nanocarbon-based product commonly employed for EF processes.

Outlook on the Role of Microbial Fuel Cells in Remediation of Environmental Pollutants with Electricity Generation

A wide variety of pollutants are discharged into water bodies like lakes, rivers, canal, etc. due to the growing world population, industrial development, depletion of water resources, improper disposal of agricultural and native wastes. Water pollution is becoming a severe problem for the whole world from small villages to big cities. The toxic metals and organic dyes pollutants are considered as significant contaminants that cause severe hazards to human beings and aquatic life. The microbial fuel cell (MFC) is the most promising, eco-friendly, and emerging technique. In this technique, microorganisms play an important role in bioremediation of water pollutants simultaneously generating an electric current. In this review, a new approach based on microbial fuel cells for bioremediation of organic dyes and toxic metals has been summarized. This technique offers an alternative with great potential in the field of wastewater treatment. Finally, their applications are discussed to explore the research gaps for future research direction. From a literature survey of more than 170 recent papers, it is evident that MFCs have demonstrated outstanding removal capabilities for various pollutants.

Simultaneous copper removal and electricity production and microbial community in microbial fuel cells with different cathode catalysts

With graphene oxide (GO), platinum carbon (Pt/C), and reduced graphene oxide (rGO) as cathode catalysts, three types of single-chamber microbial fuel cells (MFCs) were constructed for simultaneous Cu²⁺ removal and electricity production. Results indicated rGO-MFC and Pt/C-MFC had much better Cu²⁺-removing and electricity-generating performance than that of GO-MFC, and rGO-MFC presented preferable electrochemical characteristics compared with Pt/C-MFC. Microbial community analysis indicated Geobacter dominated anodic biofilms and was mainly responsible for organics degradation and electricity generation. The dual bio-selective effects by cathode catalyst and toxic Cu²⁺ resulted in different cathodic microbial communities. At high Cu²⁺ contents, Nitratireductor, Ochrobactrum, and Serratia as efficient Cu²⁺-removing genera played key roles in Pt/C-MFC, and Azoarcus predominant in cathodic biofilms of rGO-MFC might be important contributor for the favorable performance in this case.

Recent Advances in Anodes for Microbial Fuel Cells: An Overview

The recycling and treatment of wastewater using microbial fuel cells (MFCs) has been attracting significant attention as a way to control energy crises and water pollution simultaneously. Despite all efforts, MFCs are unable to produce high energy or efficiently treat pollutants due to several issues, one being the anode's material. The anode is one of the most important parts of an MFC. Recently, different types of anode materials have been developed to improve the removal rate of pollutants and the efficiency of energy production. In MFCs, carbon-based materials have been employed as the most commonly preferred anode material. An extensive range of potentials are presently available for use in the fabrication of anode materials and can considerably minimize the current challenges, such as the need for high quality materials and their costs. The fabrication of an anode using biomass waste is an ideal approach to address the present issues and increase the working efficiency of MFCs. Furthermore, the current challenges and future perspectives of anode materials are briefly discussed.

Advances in heavy metal removal by sulfate-reducing bacteria

Industrial development has led to generation of large volumes of wastewater containing heavy metals, which need to be removed before the wastewater is released into the environment. Chemical and electrochemical methods are traditionally applied to treat this type of wastewater. These conventional methods have several shortcomings, such as secondary pollution and cost. Bioprocesses are gradually gaining popularity because of their high selectivities, low costs, and reduced environmental pollution. Removal of heavy metals by sulfate-reducing bacteria (SRB) is an economical and effective alternative to conventional methods. The limitations of and advances in SRB activity have not been comprehensively reviewed. In this paper, recent advances from laboratory studies in heavy metal removal by SRB were reported. Firstly, the mechanism of heavy metal removal by SRB is introduced. Then, the factors affecting microbial activity and metal removal efficiency are elucidated and discussed in detail. In addition, recent advances in selection of an electron donor, enhancement of SRB activity, and improvement of SRB tolerance to heavy metals are reviewed. Furthermore, key points for future studies of the SRB process are proposed.

Microbial fuel cell system: a promising technology for pollutant removal and environmental remediation

The microbial fuel cell (MFC) system is a promising environmental remediation technology due to its simple compact design, low cost, and renewable energy producing. MFCs can convert chemical energy from waste matters to electrical energy, which provides a sustainable and environmentally friendly solution for pollutant degradations. In this review, we attempt to gather research progress of MFC technology in pollutant removal and environmental remediation. The main configurations and pollutant removal mechanism by MFCs are introduced. The research progress of MFC systems in pollutant removal and environmental remediation, including wastewater treatment, soil remediation, natural water and groundwater remediation, sludge and solid waste treatment, and greenhouse gas emission control, as well as the application of MFCs in environmental monitoring have been reviewed. Subsequently, the application of MFCs in environmental monitoring and the combination of MFCs with other technologies are described. Finally, the current limitations and potential future research has been demonstrated in this review.

Potential applications of algae in the cathode of microbial fuel cells for enhanced electricity generation with simultaneous nutrient removal and algae biorefinery: Current status and future perspectives

Production of biofuels and other value-added products from wastewater along with quality treatment is an uttermost necessity to achieve environmental sustainability and promote bio-circular economy. Algae-Microbial fuel cell (A-MFC) with algae in cathode chamber offers several advantages e.g. photosynthetic oxygenation for electricity recovery, CO₂-fixation, wastewater treatment, etc. However, performance of A-MFC depends on several operational parameters and also on electrode materials types; therefore, enormous collective efforts have been made by researchers for finding optimal conditions in order to enhance A-MFC performance. The present review is a comprehensive snapshot of the recent advances in A-MFCs, dealing two major parts: 1) the power generation, which exclusively outlines the effect of different parameters and development of cutting edge cathode materials and 2) wastewater treatment at cathode of A-MFC. This review provides fundamental knowledge, critical constraints, current status and some insights for making A-MFC technology a reality at commercial scale operation.