Electrodes In Microbial Fuel Cells Research Articles

Impact of CeO2 modified cathode and PANI modified anode on tannery wastewater fed microbial fuel cell performance

Microbial fuel cell (MFC) technology is getting acceptance as an emphatic, sustainable and energy efficient alternative of conventional wastewater treatment strategies. MFCs utilize exoelectrogens as biocatalysts to degrade the complex organic substances present in wastewater with simultaneous power generation. The present study was aimed at investigating the impact of MFC electrode’s modification with CeO2 nanoparticles and polyaniline (PANI) on its performance characteristics. The hydrothermal approach was employed for the synthesis of CeO2 nanoparticles followed by their deposition on carbon cloth (CC) as MFC cathode, whereas MFC’s anode i.e., CF/NF was modified by in-situe deposition of PANI. The synthesized material was characterized with FTIR, XRD, SEM, EDX and BET analysis. The experiments were performed using dual chambered MFC fed with leather tannery wastewater using modified and unmodified electrodes. The highest outcomes of power density and corresponding current density were observed with PANI@NF composite anode and CeO2@CC as cathode i.e., 279.3 mW/m2 corresponding to the current density of 581.8 mA/m2. The same MFC electrode configuration resulted in highest COD reduction, i.e., 80 % and coulombic efficiency of 19.86 %. On the other hand, MFC equipped with PANI@CF anode and CeO2@CC cathode also displayed comparable results. It was ascertained that modification of NF/CF anode with PANI (conductive polymer) and CC cathode with CeO2 nanoparticles have significantly improved the overall MFC operational performance regarding tannery wastewater treatment and bioelectricity generation.

Renewable Carbonaceous Materials from Biomass in Catalytic Processes: A Review.

This review paper delves into the diverse ways in which carbonaceous resources, sourced from renewable and sustainable origins, can be used in catalytic processes. Renewable carbonaceous materials that come from biomass-derived and waste feedstocks are key to developing more sustainable processes by replacing traditional carbon-based materials. By examining the potential of these renewable carbonaceous materials, this review aims to shed light on their significance in fostering environmentally conscious and sustainable practices within the realm of catalysis. The more important applications identified are biofuel production, tar removal, chemical production, photocatalytic systems, microbial fuel cell electrodes, and oxidation applications. Regarding biofuel production, biochar-supported catalysts have proved to be able to achieve biodiesel production with yields exceeding 70%. Furthermore, hydrochars and activated carbons derived from diverse biomass sources have demonstrated significant tar removal efficiency. For instance, rice husk char exhibited an increased BET surface area from 2.2 m2/g to 141 m2/g after pyrolysis at 600 °C, showcasing its effectiveness in adsorbing phenol and light aromatic hydrocarbons. Concerning chemical production and the oxidation of alcohols, the influence of biochar quantity and pre-calcination temperature on catalytic performance has been proven, achieving selectivity toward benzaldehyde exceeding 70%.

Percolation-Modeling Comparison Between the Conductivities of Zinc-Graphene Quantum Dot Nanocomposite and Graphite during Extracellular Electron Transfer in Microbial Fuel Cell Electrodes

Percolation-Modeling Comparison Between the Conductivities of Zinc-Graphene Quantum Dot Nanocomposite and Graphite during Extracellular Electron Transfer in Microbial Fuel Cell Electrodes

Bi-directional regulation of electroactive microbial community using Au/antimicrobial peptide nanocomposite

The power generation and pollutants removal efficiencies of mixed electroactive microbial community rely on the effective electron transfer between outer membrane proteins of electroactive electricigens. However, the poor conductivity of protein and various non-electrogenic bacteria greatly hinder the electron transfer and effective contact between electricigens. Herein, we report a novel “bi-directional” microbial community regulation method that can selectively inhibit Gram-positive non-electrogenic bacteria and enhances the conductivity and electron transfer between electrogenic bacteria and the electrode in MFC by taking the advantages of the excellent conductive and bacteriostatic properties of Au/Nisin nanocomposite. The Au/Nisin stimulation endows microbial fuel cell (MFC) a high-efficiency functional community, which increases the power density and decolorization rate by 103 % and 33 %, respectively. The high conductivity, and selectivity and antimicrobial activity of the nanocomposite improve the electrochemical activity of the bioanode, hereby promoting the microbial extracellular electron transfer and increasing the proportion of electrogenic bacteria such as Proteobacteria, Bacteroidetes and Desulfovibrio in the biofilm. Our work successfully demonstrates that the construction of multifunctional metallic peptide nanocomposite can effectively regulate microbial community to improve the electrochemical performance of MFC.

Assessing the efficacy of bio-composite starch/biochar based microbial fuel cell Pb(II) removal from contaminated seawater

The efficient removal of toxic chemicals from wastewater using effective sorbents has gained significant attention in recent years. In this study, a starch/biochar composite was synthesized from rice straw to achieve the removal of Pb(II) from wastewater. The highest performing starch/biochar composite was then utilized as a microbial fuel cell electrode for generating electricity in synthetic seawater contaminated with Pb(II) and petroleum hydrocarbons. Results showed that the maximal power density and current density were 2.18±0.20 W/m3 and 8.33±0.50 A/m3, respectively, and that the composite achieved removal rates of 95.10±1.50% for Pb(II) and 55.10±2.20% for petroleum hydrocarbons. These findings suggest that the starch/biochar composite can serve as an effective sorbent for remediating environmental contamination, while also having potential for use in sustainable energy generation.

Urethane-based electrode material for microbial fuel cells

Nowadays, global warming and fossil fuel depletion are two unsolved problems. Research is underway on renewable energies, which are new energy sources. This study aims to improve the performance of microbial fuel cells (MFCs), a renewable energy generation method. Urethane was used as the electrode material for MFC. Urethane is an excellent material suitable for use as MFC electrodes because of its durability, porosity, and other properties. However, urethane itself is not conducive. This study used conductive urethane, which is coated with activated carbon powder, as the electrode material. This material is used in deodorizing filters, air conditioning filters, and air cleaner filters. To improve the performance of MFC, carbon nanotubes and activated carbon powder were added to the urethane electrodes. PTFE was also used to improve cathodic function. PTFE is used as a binder in many microbial fuel cells. The performance of the electrodes was compared. The analysis included power density measurements and discharge characteristics. It was confirmed that the use of PTFE improves the power density by a factor of two or more. The MFC generated a maximum power density of 28.27 μW/cm2. SEM image analysis of the electrode after the experiment confirmed that PTFE could reduce the adhesion of microorganisms on the cathode surface. These results imply that the use of conductive urethanes as electrodes in MFCs is effective. The addition of carbon nanotubes, activated carbon powder, and PTFE has enabled the use of urethane as an electrode material for microbial fuel cells.

Impact of Self-Fabricated Graphene–Metal Oxide Composite Anodes on Metal Degradation and Energy Generation via a Microbial Fuel Cell

Microbial fuel cells (MFCs) are thought to be ecologically friendly, despite electron transport and generation challenges. In order to address this, the efficiency of MFCs was investigated using two different anode electrodes made from biomass: graphene oxide (GO) and graphene oxide-metal oxide (GO-MO) (GO-ZnO). After 18 days of operation, the maximum power density for GO was 0.69 mW/m2, whereas the maximum power density for GO-ZnO was 1.05 mW/m2. Furthermore, the ability of MFCs to transform the soluble metal ions (Cd2+, Cr3+, Pb2+, and Ni2+) into an insoluble state was investigated, which is a secondary use of MFCs with significant benefits. In the soluble state of metal ion transformation into an insoluble state, the rate of GO-ZnO was higher (92.71%) than that of GO (81.20%). The outcomes of material, analytical, and biological tests undertaken to validate the efficiency of anodes are presented. It has been shown that using innovative materials as electrodes in MFCs is a potential method for improving electron transport. Furthermore, as an organic substrate, food waste seems to be a viable alternative to more traditional options. In light of these discoveries, we investigate various unanswered issues and possibilities for MFCs. Organic substrate evaluation trials were also included in the present results to demonstrate that organic waste may be a reliable source of MFC performance. This article also has a thorough discussion of food waste oxidation, as well as challenges and future recommendations.

Application of Low-Cost Plant-Derived Carbon Dots as a Sustainable Anode Catalyst in Microbial Fuel Cells for Improved Wastewater Treatment and Power Output

Microbial fuel cells (MFC) can generate electric energy from wastewater which can be enhanced further by anode catalysts. The recovery of electrons produced by oxidation of organics catalyzed by bacteria in the anode was enhanced when carbon dots(CDs) were added into the MFC. In this present study, a novel strategy for designing anode material and the fabrication of a high-efficient and environmentally friendly anode for energy generation from wastewater was reported. The CDs were synthesized by the pyrolysis of a peanut shell at the temperature of 250 °C for 2 h with a heating rate of 10 °C min−1. Thus synthesized CDs were characterized by transmission electron microscopy (TEM), UV/Vis spectroscopy, and fluorescence spectroscopy. The TEM analysis showed morphology with an average size of 1.62 nm. The UV/Vis absorbance of the CDs shows a wide absorption band without a characteristic peak. The excitation spectrum of CDs recorded at the emission wavelength of 440 nm exhibits a peak around 320 nm. CDs were investigated as an anode material in a MFC utilizing acetate as the organic substrate. The average chemical oxygen demand (COD) removal in closed circuit operation mode was 89%. The maximum power density production (7.2 W/m3) was observed in MFC containing 1 mg/cm2 CD-impregnated anode (CDsIA). The CDsIA provides the ability to promote efficient biofilm formation. These results emphasize the application of CD-based electrodes in MFCs for the simultaneous treatment of wastewater and electricity generation while also providing additional benefits.

Evaluation of the Datura peels derived biochar-based Anode for enhancing power output in microbial fuel cell application

Activated biochar utilizing Datura metel peel was synthesized using pyrolysis at 800oC and activated using KOH. The resulting biochar was investigated as an anode material in a Pseudomonas aeruginosa powered microbial fuel cell (MFC) utilizing acetate as the substrate for the first time. The average chemical oxygen demand (COD) elimination was 85.4% in closed circuit mode. The maximum power production was observed in MFC containing 1 mg/cm2 biochar impregnated anode with a peak power density measured at 584.2 mW/m2. The results of biochar characterization using Field Emission Scanning Electron Microscope (FE-SEM) illustrates the presence of spherical globular texture which indicates the nano spherical structure of carbon nanoparticles in the biochar. The porous texture and interlinked characteristics of carbon nano-spheres can significantly enhance the diffusion of electrolyte ions. The confocal laser scanning microscopy (CLSM) results show a high number of cell biomass on 1 mg/cm2 biochar impregnated anode, indicating that 1 mg/cm2 biochar promotes enhanced biofilm formation. These results emphasize the utilization of biochar as electrodes in MFCs to allow for simultaneous wastewater treatment and electricity generation .

Electrical discharge machining as a surface treatment process for improving the performance of microbial fuel cells

Microbial fuel cells (MFCs), which generate low-pollution power through feeding organic trace minerals to bacteria, are crucial for applications involving energy recovery and environmental protection. In MFCs, electrodes critically influence the electrocatalytic process. In this study, an electrical-discharge-machining (EDM)-based surface treatment method for MFC electrodes was applied to a stainless-steel mesh (SSM), which was selected as an anode substrate. The experimental results indicated that EDM surface treatment formed a recast layer on the SSM anode surface. A few defects such as cracks and notches were observed after EDM surface treatment, which increased the surface and surface roughness of the SSM anode. To verify the effectiveness of the proposed EDM treatment, an Escherichia coli (HB101)-based single-chamber MFC system was fabricated, and the electrochemical activity of the EDM-treated anode was investigated through electrochemical analysis. The maximum power density of the MFCs equipped with the untreated SSM anode and the EDM-treated SSM anode under a pulse current of 1.5 A were 101.37 and 205.94 mW m−2, respectively. Thus, EDM surface treatment increased the power generated by the MFC by a factor of approximately 2. The proposed novel EDM surface treatment, therefore, has potential for development as a standard processing procedure for metal electrode substrates.

(Digital Presentation) Electrochemical Single Impact Method for Electroactive Bacterial Detection Onto Carbon Ultramicroelectrode

This work aims to design a high sensitivity and selectivity biosensor based on the electrochemistry of single impacts onto ultramicroelectrode (UME) to detect and identify various bacterial strains. The main objective is to establish a unique electrochemical signature for each bacterial cell through the individual impact event signal on the surface of the UME [1, 2]. First, we focus on the detection of well-known electroactive Gram-negative bacteria such as Shewanella oneidensis in order to be able to selectively detect these different single cells. In this case, the strategy currently used is to record a chronoamperometric curve in an aqueous potassium phosphate buffer (pH = 7.4) solution containing a redox probe at an UME polarized at the oxidation or reduction potential of the electrochemical active aqueous species and to observe a “current step” when one bacterium impacts the UME, corresponding to a “blocking effect” [3] (Figure A). The response signal expected from single bacterium collision may also be a “current spike” corresponding to either the own electrochemical activity of the bacterium toward the redox probe and the UME applied potential or a “bouncing effect” of the bacterium which does not stick onto UME surface (Figure B).In order to be able to identify the type of bacterial cell striking the UME surface, an adapted functionalization (covalent grafting via reduction of diazonium aryl salts) with appropriate affinity (bio)chemical species such as antibodies or aptamers could be performed. This strategy could confer to the UME surface a selectivity of the signal generated during single impacts. For example, the electro-grafting of diazo-pyridinium cations for microbial fuel cell electrodes showed to promote and improve the development of bacterial electroactive films [4].[1] E. Lebègue, N. L. Costa, R. O. Louro, F. Barrière, J. Electrochem. Soc. 16 (2020) 105501[2] A. T. Ronspees, S. N.Thorgaard, Electrochimica Acta. 278 (2018) 412-420[3] G. Guanyue, W. Dengchao, B. Ricardo, Z. Jinfang, M. Michael V. Anal. Chem. 90 (2018) 12123−12130[4] H. Smida, E. Lebègue, J-F. Bergamini, F. Barrière, C. Lagrost, Bioelectrochemistry. 120 (2018) 157-165 Figure 1

Metal mixed biochar electrodes for the generation of electricity with high power density in microbial fuel cell

The current analysis points on the available resources of lessening the expense of electrodes and diminishing climate contamination utilizing waste materials. The microbial fuel cell (MFC) ability was evaluated by utilizing electrodes made from Biochar. For scaling up low cost MFC electrodes were modified by using less expensive materials like Biomass. Electrodes were made of Copper (Cu), Cobalt (Co) extends blended in with groundnut shell wastes biochar materials after the carbonization process. Power output of electrodes were AC-Cu 173.20 mW m−2) and AC-Co 205.49 mW m−2). The open circuit potential of cobalt oxide modified electrodes showed 0.843 V. Our results showed that the activated groundnut shell wastes with AC-Co metal anode gives the greatest power yield. Subsequently, CS-Cu anodes are progressively suitable, have more prominent biocompatibility, viable and versatile for application in the microbial energy unit. Among these two proposed anodes, CS-Co electrode has a tremendous potential for most extreme performances and development a practical maintainable MFC.

(Digital Presentation) Electrochemical Characterization of Microbial Fuel Cell Electrodes Using Cyclic Voltammetry and Electrochemical Impedance Spectroscopy

Renewable energy sources are required to lessen energy generation's reliance on fossil fuels. Microbial fuel cells (MFC) exploit microbial metabolic processes to oxidize organic matter to generate energy from wastewater; they serve as a low-cost, sustainable form of wastewater management. Despite the development of effective MFCs, low efficiency and power density have prevented their widespread adoption over traditional fuel cells. Modification of MFC electrodes has been investigated as a means to improve their limited power output. Here we assessed the MFC carbon cloth electrodes and compared them to a traditional glassy carbon, and clean carbon cloth. The electrochemical properties of the electrode surfaces were explored using a three electrode cell consisting of a platinum wire counter electrode and Ag/ AgCl/ 1M KCl reference electrode. Electrolyte dependent studies were conducted in phosphate buffered saline (PBS) in the presence of ferri/ferrocyanide. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), differential pulse voltammetry (DPV), and square wave voltammetry (SWV) of the solution redox couple with various working electrode were performed in order to characterize electrode surface, prior, and post MFC use. The ultimate goal is to optimize the electrode surface chemistry to promote optimal MFC performance.

Dynamics of a Bacterial Community in the Anode and Cathode of Microbial Fuel Cells under Sulfadiazine Pressure.

Microbial fuel cells (MFCs) could achieve the removal of antibiotics and generate power in the meantime, a process in which the bacterial community structure played a key role. Previous work has mainly focused on microbes in the anode, while their role in the cathode was seldomly mentioned. Thus, this study explored the bacterial community of both electrodes in MFCs under sulfadiazine (SDZ) pressure. The results showed that the addition of SDZ had a limited effect on the electrochemical performance, and the maximum output voltage was kept at 0.55 V. As the most abundant phylum, Proteobacteria played an important role in both the anode and cathode. Among them, Geobacter (40.30%) worked for power generation, while Xanthobacter (11.11%), Bradyrhizobium (9.04%), and Achromobacter (7.30%) functioned in SDZ removal. Actinobacteria mainly clustered in the cathode, in which Microbacterium (9.85%) was responsible for SDZ removal. Bacteroidetes, associated with the degradation of SDZ, showed no significant difference between the anode and cathode. Cathodic and part of anodic bacteria could remove SDZ efficiently in MFCs through synergistic interactions and produce metabolites for exoelectrogenic bacteria. The potential hosts of antibiotic resistance genes (ARGs) presented mainly at the anode, while cathodic bacteria might be responsible for ARGs reduction. This work elucidated the role of microorganisms and their synergistic interaction in MFCs and provided a reference to generate power and remove antibiotics using MFCs.

Oxygen Reduction Reaction with Manganese Oxide Nanospheres in Microbial Fuel Cells.

Operating microbial fuel cells (MFCs) under extreme pH conditions offers a substantial benefit. Acidic conditions suppress the growth of undesirable methanogens and increase redox potential for oxygen reduction reactions (ORRs), and alkaline conditions increase the electrocatalytic activity. However, operating any fuel cells, including MFCs, is difficult under such extreme pH conditions. Here, we demonstrate a pH-universal ORR ink based on hollow nanospheres of manganese oxide (h-Mn3O4) anchored with multiwalled carbon nanotubes (MWCNTs) on planar and porous forms of carbon electrodes in MFCs (pH = 3–11). Nanospheres of h-Mn3O4 (diameter ∼ 31 nm, shell thickness ∼ 7 nm) on a glassy carbon electrode yielded a highly reproducible ORR activity at pH 3 and 10, based on rotating disk electrode (RDE) tests. A phenomenal ORR performance and long-term stability (∼106 days) of the ink were also observed with four different porous cathodes (carbon cloth, carbon nanofoam paper, reticulated vitreous carbon, and graphite felt) in MFCs. The ink reduced the charge transfer resistance (Rct) to the ORR by 100-fold and 45-fold under the alkaline and acidic conditions, respectively. The current study promotes ORR activity and subsequently the MFC operations under a wide range of pH conditions, including acidic and basic conditions.

Utilizing Biomass-Based Graphene Oxide-Polyaniline-Ag Electrodes in Microbial Fuel Cells to Boost Energy Generation and Heavy Metal Removal.

Although regarded as environmentally stable, bioelectrochemical fuel cells or, microbial fuel cells (MFCs) continue to face challenges with sustaining electron transport. In response, we examined the performance of two graphene composite-based anode electrodes—graphene oxide (GO) and GO–polymer–metal oxide (GO–PANI–Ag)—prepared from biomass and used in MFCs. Over 7 days of operation, GO energy efficiency peaked at 1.022 mW/m2 and GO–PANI–Ag at 2.09 mW/m2. We also tested how well the MFCs could remove heavy metal ions from synthetic wastewater, a secondary application of MFCs that offers considerable benefits. Overall, GO–PANI–Ag had a higher removal rate than GO, with 78.10% removal of Pb(II) and 80.25% removal of Cd(II). Material characterizations, electrochemical testing, and microbial testing conducted to validate the anodes performance confirmed that using new materials as electrodes in MFCs can be an attractive approach to improve the electron transportation. When used with a natural organic substrate (e.g., sugar cane juice), they also present fewer challenges. We also optimized different parameters to confirm the efficiency of the MFCs under various operating conditions. Considering those results, we discuss some lingering challenges and potential possibilities for MFCs.

Nanocoating of microbial fuel cell electrodes for enhancing bioelectricity generation from wastewater

Microbial fuel cells (MFCs) are devices where bacteria generate electrical energy by oxidizing organic matter in wastewater. The implementation of MFCs on a commercial scale is limited due to electrode resistances, which are one of the key factors limiting electricity generation. This study presents a method to maximize the electrical power production from MFCs by coating the electrodes using nanomaterials which leads to prototyping novel electrodes having higher electrical conductivity than common electrodes. The voltage reached 1.234 V directly after operating the MFCs, with nanocoated electrodes, and showed voltage stability till the end of the 140 h interval with a peak value of 1.367 V with a maximum areal power density of 116 mW m−2 and a maximum volumetric power density of 15.6 mW m−3. However, the voltage of the control (without coating) was steadily increased to 0.616 V after 22 h with a maximum areal power density of 23.6 mW m−2 and a maximum volumetric power density of 3.2 mW m−3 then showed voltage stability till the end of the 140 h interval. It was found that the coulombic efficiency of the MFCs where its electrodes are coated with graphitic carbon nitride nanosheets was higher than graphene, carbon nanotubes, and the control in a descending order, respectively. By this method, it is possible to improve the electrical conductivity of the MFCs which results in increasing the generated electrical power by 4.9 times the conventional method.

Wood carbon electrode in microbial fuel cell enhances chromium reduction and bioelectricity generation.

Microbial fuel cell (MFC) is a recommended treatment to remediate hexavalent chromium (Cr(VI)) in wastewater. In this study, a wood carbon (WC) electrode was introduced in MFC to enhance the Cr(VI) removal efficiency. WC electrode in MFC completely removed Cr(VI) as compared to the carbon cloth (31.12%) and carbon felt (34.83) within 48 h of operation at 20 mg L-1 of Cr(VI) concentration. The maximum power density of WC electrode was 62.59 mW m-2 higher than 0.115 and 3.154 mW m-2 of carbon cloth and felt respectively. The specific surface area of WC increased to 158.47 m-2 g-1 after high-temperature carbonization, and electrochemical tests indicate it has higher electrocatalytic ability. Therefore, WC might be a good electrode material to effectively remove Cr(VI) and generate bioelectricity simultaneously.

Generation of Bioelectricity from Organic Fruit Waste

This research proposes an alternative for companies and farmers through the production of electricity using microbial fuel cells (MFCs) using waste from export products. Nine MFCs were manufactured with zinc and copper electrodes; and as substrates, pineapple, potato and tomato pulp wastes were used in the anode chamber, and residual sludge in the cathode chamber. It was observed that the MFCs with pineapple substrate generated higher values of the electrical parameters, resulting in voltage and current values of 0.3484 ± 0.003 V and 27.88 ± 0.23 mA, respectively. It was also observed that the maximum power density was 0.967 ± 0.059 W/cm2 at a current density of 0.04777 A/cm2 for the same substrate. Acid pH values were observed in the three samples, while the conductivity reached its maximum value on day 23 (69.47 ± 0.91 mS/cm) which declined until the last day of monitoring; the turbidity values increased abruptly after day 22 until the last day where a value of 200.3 ± 2.52 UNT was observed for the pineapple substrate. The scanning electron microscopy for the pineapple substrate MFC electrodes shows the formation of a porous biofilm on the zinc and copper electrodes. These results show that a new form of electricity production has been achieved by generating high voltage and current values, using low-cost materials.

A sustainable approach towards utilization of plastic waste for an efficient electrode in microbial fuel cell applications

Microbial fuel cells (MFC) are a novel technique for power generation from wastewater. A number of approaches for the modification of physical as well as chemical properties of the electrodes can be employed to attain the maximum output power density and high power electricity. The use of an active organic linker, extracted from waste residue (plastic), for the synthesis of porous nanostructured materials would be beneficial in the fabrication of electrodes for MFC. Herein, terephthalic acid monomer (t) derived from plastic waste was successfully applied as an electrochemically active linking unit to form an iron-based metal-organic framework (Fe-t-MOF: MIL-53(Fe)). The synthesized Fe-t-MOF was further modified with conducting polymer (polyaniline (PANI)). The produced nanocomposite (Fe-t-MOF/PANI) was coated on stainless steel (SS) disk (as a current collector) for use as an electrode component of the MFC system. The power density, open circuit potential (OCP), and a limiting current density of the MFC are 680 mW/m2, 0.67 V, and 3500mA/m2, respectively. The technique opted here should help search a novel, efficient, sustainable, and cost-effective route for the modification of the plastic waste into an MFC electrode to achieve bioenergy production through wastewater treatment.