Microbial Fuel Cell For Generation Research Articles

Model-based Evaluation of the Effect of Temperature on Electric Power Generation in Microbial Fuel Cells

Model-based Evaluation of the Effect of Temperature on Electric Power Generation in Microbial Fuel Cells

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.

Effect of lignite activated coke packing on power generation and phenol degradation in microbial fuel cell treating high strength phenolic wastewater

Microbial fuel cell (MFC) is commonly used for easily biodegradable substances, yet its application for high strength phenolic wastewater treatment remains a challenge. This study incorporates lignite activated coke (LAC) into MFC to alleviate the inhibition of phenol and facilitate power generation of MFC. The power generation and phenol degradation in both LAC-MFC and control MFC were investigated at phenol concentrations of 500 mg/L, 700 mg/L and 1000 mg/L. The results showed that the maximum power density in LAC-MFC was maintained in the range of 252.3–278.7 mW/m2 when the phenol concentration increased from 500 mg/L to 1000 mg/L, whereas it was decreased from 246.5 mW/m2 to 167.5 mW/m2 in control-MFC. This corresponds to a high phenol removal of 89.4% to 94.5% in LAC-MFC but a significant decrease from 80.7% to 50.8% in control MFC. The inhibition coefficient (Ki) calculated from Haldane inhibition model decreased by 24.3% in LAC-MFC compare with control MFC, suggesting that the stress of high concentrations of phenol on MFC was largely relieved. In addition, the phenol degradation intermediate products of 2-hydroxymuconic semialdehyde, 4-hydroxybenzoic acid, 4-hydroxy-3-methylbenzoic acid were apparently lower in LAC-MFC than control MFC, indicating that the biodegradation of phenol was enhanced in LAC-MFC. High-throughput sequencing analysis revealed that Pseudomonas, Desulfuromonas, and Hydrogenophaga might be associated with phenol degradation and power generation in LAC-MFC. Because of its effectiveness in alleviating the toxic effects of phenol, LAC packing is a promising MFC technology for high strength phenolic wastewater treatment.

Degradation and biotoxicity of azo dyes using indigenous bacteria-acclimated microbial fuel cells (MFCs)

This study explored a bioenergy platform of biodegradability and toxicity evaluation through microbial fuel cells (MFCs) modules for simultaneous decolorization and bioelectricity generation. The most appropriate decolorizer consortia NIU pond exhibited the extent of decolorization: Sunset Yellow FCF (93 %), Allura Red (96.6 %), and Tartrazine (91.41 %) in 3, 8, 12 h respectively. The ranking for bioelectricity generation in MFCs (unit: mW m−2) (Sunset Yellow FCF Degradation) was hot spring water (46.42) > hot spring soil (22.17) > NIU pond (17.75) > NIU soil (7.89). In the presence of the dye, power density was increased by 88 %, 84 % and 27 % for NP, HS, and HW, respectively. Acclimation process was inspected in terms of bioenergy-extracting capability to evaluate toxicity potency of model dyes. According to metagenomics analysis upon microbial populations before and after acclimation, indigenous microbial community was only predominated by Pseudomonas monteilii and of Bacillus pumilus. Significant increased biodiversity was evolved under selection of dye stress. After acclimation, community ecology in the consortia contained Klebsiella, Citrobacter, Enterococcus faecalis, Lactobacillus lactis, and Escherichia shigella. Tandem mass spectrometric analysis pointed out sunset yellow ECF was gradually degraded and decolorized intermediates steadily accumulated. MFC modules were promising platforms to select candidate biodecolorizers from microbial populations.

Enhancing the Performance of Microbial Fuel Cell by Using Chloroform Pre-treated Mixed Anaerobic Sludge to Control Methanogenesis in Anodic Chamber.

Formation of methane in the anodic chamber of a microbial fuel cell (MFC) indicates an energy inefficiency in electricity generation as the energy required for electrogenesis gets redirected to methanogenesis. The hypothesis of this research is that inhibition of methanogenesis in the mixed anaerobic anodic inoculum is associated with an enhanced activity of the electrogenic bacterial consortia. Hence, the primary objective of this investigation is to evaluate the ability of chloroform to inhibit the methanogenesis at different dosing to enhance the activity of electrogenic consortia in MFC. A higher methane inhibition and hence an enhanced performance of MFC was achieved when mixed anaerobic sludge, collected from septic tank, was used as inoculum after pre-treatment with 0.25% (v/v) chloroform dosing (MFC-0.25CF). The MFC-0.25CF attained a maximum power density of 8.51W/m3, which was more than twice as that of MFC inoculated with untreated sludge. Also, a clear correlation between the chloroform dosing, methane inhibition, wastewater treatment, and power generation was established, which demonstrated the effectiveness of the technique in enhancing power generation in MFC along with adequate biodegradation of organic matter present in wastewater at an optimum chloroform dosing of 0.25% (v/v) to inhibit methanogenesis.

Nitrogen oxide gas purification using carbon in water as reducing reagent with the aid of microbial fuel cell

Microbial Fuel Cell (MFC) can degrade the organic matter (OM) in wastewater at the anode and transfer electrons to the cathode. In this work, the harmful NOX gas was used as electron acceptor in MFC and converted to harmless N2. The OM in water was indirectly used as a zero-cost reducing agent for NOx removal. More than 80% of NOX was removed continuously by MFC at room temperature. The NOX was directly reduced to N2 at MFC cathode and the cathode activity played a key role on enhancing the NOX removal. The NOX removal efficiency by the cathode of high potential was 1.37 times that by the cathode of low potential. When O2 coexisting with NO as the electron acceptor, not only the NOX removal but also the power output of MFC was improved greatly. The presence of NOX did not decrease the power generation of MFC under the same O2 concentration. The MFCs showed good stability for NOX treatment and power output. Moreover, the possible pathways and advantages of NOX removal by MFC were discussed in detail. These results indicated that the MFC system has the potential to treat wastewater, purify flue gas and recover energy simultaneously.

Three-dimensional graphitic mesoporous carbon-doped carbon felt bioanodes enables high electric current production in microbial fuel cells

Microbial fuel cells (MFCs) represent a new approach that can simultaneously enhance the treatment of waste streams and generate electricity. Although MFCs represent a promising technology for renewable energy production, they have not been successfully scaled-up mainly due to the relatively-low electricity generation and high cost associated with MFCs operation. Here, we investigated whether graphitic mesoporous carbon (GMC) decoration of carbon felt would improve the conductivity and biocompatibility of carbon felt anodes, leading to higher biomass attachment and electricity generation in MFCs fed with an organic substrate. To test this hypothesis, we applied 3 different GMC loading (i.e., 2, 5, and 10 mg/cm2 of anode surface area) in MFCs compared to control MFCs (with pristine carbon felt electrodes). We observed that the internal resistances of modified anodes with GMC were 1.2–2.3-order of magnitude less than pristine carbon felt anode, leading to maximum power densities of 70.3, 33.3, and 9.8 mW/m2 for 10, 5, and 2 mg/cm2-doped anode, respectively compared to only 3.8 mW/m2 for the untreated carbon felt. High-throughput sequencing revealed that increasing the GMC loading rate was associated with enriching more robust anode-respiring bacteria (ARB) biofilm community. These results demonstrate that 3-D GMC-doped carbon felt anodes could be a potential alternative to other expensive metal-based electrodes for achieving high electric current densities in MFCs fed with organic substrates, such as wastewater. Most importantly, high electron transfer capability, strong chemical stability, low cost, and excellent mechanical strength of 3-D GMC-doped carbon felt open up new opportunities for scaling-up of MFCs using cheap and high-performance anodes.

Microbial Structure and Energy Generation in Microbial Fuel Cells Powered with Waste Anaerobic Digestate

Development of economical and environment-friendly Microbial Fuel Cells (MFCs) technology should be associated with waste management. However, current knowledge regarding microbiological bases of electricity production from complex waste substrates is insufficient. In the following study, microbial composition and electricity generation were investigated in MFCs powered with waste volatile fatty acids (VFAs) from anaerobic digestion of primary sludge. Two anode sizes were tested, resulting in organic loading rates (OLRs) of 69.12 and 36.21 mg chemical oxygen demand (COD)/(g MLSS∙d) in MFC1 and MFC2, respectively. Time of MFC operation affected the microbial structure and the use of waste VFAs promoted microbial diversity. High abundance of Deftia sp. and Methanobacterium sp. characterized start-up period in MFCs. During stable operation, higher OLR in MFC1 favored growth of exoelectrogens from Rhodopseudomonas sp. (13.2%) resulting in a higher and more stable electricity production in comparison with MFC2. At a lower OLR in MFC2, the percentage of exoelectrogens in biomass decreased, while the abundance of genera Leucobacter, Frigoribacterium and Phenylobacterium increased. In turn, this efficiently decomposed complex organic substances, favoring high and stable COD removal (over 85%). Independent of the anode size, Clostridium sp. and exoelectrogens belonging to genera Desulfobulbus and Acinetobacter were abundant in MFCs powered with waste VFAs.

Tuning of Surface Characteristics of Anodes for Efficient and Sustained Power Generation in Microbial Fuel Cells.

The present study reports about the fabrication of a three-dimensional (3D) macroporous steel-based scaffold as an anode to promote specifically bacterial attachment and extracellular electron transfer to achieve power density as high as 1184 mW m-2, which is far greater than that of commonly used 3D anode materials. The unique 3D open macroporous configuration of the anode and the microstructure generated by the composite coating provide voids for the 3D bacterial colonization of electroactive biofilms. This is attributed to the sizeable interfacial area per unit volume provided by the 3D corrugated electrode that enhanced the electrochemical reaction rate compared to that of the flat electrode, which favors the enhanced mass transfer and substrate diffusion at the electrode/electrolyte interface and thereby increases the charge transfer by reducing the electrode overpotential or interfacial resistance. In addition, bacterial infiltration into the interior of the anode renders large reaction sites for substrate oxidation without the concern of clogging and biofouling and thereby improves direct electron transfer. A very low overpotential (-27 mV) with a very low internal resistance (7.104 Ω cm2) is achieved with the fabricated microbial fuel cell (MFC) that has a modified 3D corrugated electrode. Thus, easier and faster charge transfer at the electrode-electrolyte interface is confirmed. The study presents a revolutionary practical approach in the development of highly efficient anode materials that can ensure easy scale-up for MFC applications.

Exploring community evolutionary characteristics of microbial populations with supplementation of Camellia green tea extracts in microbial fuel cells

This first-attempt study deciphered combined characteristics of species evolution and bioelectricity generation of microbial community in microbial fuel cells (MFCs) supplemented with Camellia green tea (GT) extracts for biomass energy extraction. Prior studies indicated that polyphenols-rich extracts as effective redox mediators (RMs) could exhibit significant electrochemical activities to enhance power generation in MFCs. However, the supplementation of Camellia GT extract obtained at room temperature with significant redox capabilities into MFCs unexpectedly exhibited obvious inhibitory effect towards power generation. This systematic study indicated that the presence of antimicrobial components (especially catechins) in GT extract might significantly alter the distribution of microbial community, in particular a decrease of microbial diversity and evenness. For practical applications to different microbial systems, pre-screening criteria of selecting biocompatible RMs should not only consider their promising redox capabilities (abiotic), but also possible inhibitory potency (biotic) to receptor microbes. Although Camellia tea extract was well-characterized as GRAS energy drink, some contents (e.g., catechins) may still express inhibition towards organisms and further assessment upon biotoxicity may be inevitably required for practice.

Microbial synergistic interactions enhanced power generation in co-culture driven microbial fuel cell

An understanding of the inter-species relationships, especially their metabolic network in a mixed-culture system, is crucial to design an effective inoculum for enhancing the power generation of wastewater fed microbial fuel cell (MFC). In the present study, the influence of microbial mutualistic interactions on the power generation of palm oil mill effluent fed MFCs has been widely investigated by designing several co-culture and mixed culture inoculums. Among the different inoculum compositions, the highest power density of 14.8 W/m3 was achieved by Pseudomonas aeruginosa and Klebsiella variicola co-culture inoculum due to their synergistic relationships which were inter-linked via fermentation-based metabolites. Besides, the interaction of K. variicola and Bacillus cereus positively influenced the power generation resulting in a maximum power density of 11.8 W/m3 whereas the antagonistic relationship between B. cereus and P. aeruginosa resulted in a lower power generation of 1.9 W/m3. The microbial mutualistic interactions were investigated with polarization, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), as well as by using metabolite and biofilm analysis. It was observed that the synergism between bacteria enhanced power generation through the production of higher electron shuttling mediators and efficient biofilm formation as evidenced by polarization, CV and EIS analysis. In contrast, the antagonistic relationship resulted in production of cell inhibiting metabolites leading to the formation of ineffective biofilm. These findings demonstrate that the synergistic interaction between or within microorganisms is emergent in designing co-culture or mixed-culture inoculum for achieving maximum power generation in MFCs.

Bioelectricity generation using iron(II) molybdate nanocatalyst coated anode during treatment of sugar wastewater in microbial fuel cell

Microbial Fuel Cell (MFC) acts as an auspicious technology that converts chemical energy into electricity and removes the pollutants from wastewater by means of catalytic action of microorganisms. Recently, advances in nanofabrication provide a unique opportunity to develop an efficient electrode for the MFC with remarkable structural, electrical and chemical properties. The main aim of the present work was to investigate the effect of Iron(II)molybdate (FeMoO4) as a novel anode catalyst on improving power generation in MFC using sugar wastewater as a substrate. XRD and SEM analyses were done for nanocatalyst confirmation and to understand the morphology of the FeMoO4 coated electrodes. The MFC performance was investigated and compared with the nanocomposite coated electrode and control (plain) electrode, respectively. The experimental results indicated that the FeMoO4 coated electrode achieved the maximum power density of 106 ± 3 mW/m2, coloumbic efficiency of 21.3 ± 0.5% and COD removal efficiency of 79.8 ± 1.5% respectively. The results demonstrated that the synthesized nanoparticles could act as an efficient anode catalyst for enhancing the MFC performance.

Co-metabolism for enhanced phenol degradation and bioelectricity generation in microbial fuel cell

Co-metabolism is one of the effective approaches to increase the removal of refractory pollutants in microbial fuel cells (MFCs), but studies on the links between the co-substrates and biodegradation remain limited. In this study, four external carbon resources were used as co-substrates for phenol removal and power generation in MFC. The result demonstrated that acetate was the most efficient co-substrate with an initial phenol degradation of 78.8% and the voltage output of 389.0 mV. Polarization curves and cyclic voltammogram analysis indicated that acetate significantly increased the activity of extracellular electron transfer (EET) enzyme of the anodic microorganism, such as cytochrome c OmcA. GC-MS and LC-MS results suggested that phenol was biodegraded via catechol, 2-hydroxymuconic semialdehyde, and pyruvic acid, and these intermediates were reduced apparently in acetate feeding MFC. The microbial community analysis by high-throughput sequencing showed that Acidovorax, Geobacter, and Thauera were predominant species when using acetate as co-substrate. It can be concluded that the efficient removal of phenol was contributed to the positive interactions between electrochemically active bacteria and phenolic degradation bacteria. This study might provide new insight into the positive role of the co-substrate during the treatment of phenolic wastewater by MFC.

The inhibiting effect of oxygen diffusion on the electricity generation of three-chamber microbial fuel cells

Microbial fuel cell (MFC) as an emerging biotechnology is applied to generate electricity from the degradation of organic matter. This work explores the performance of the three-chamber MFCs in regard to oxygen diffusion with air aeration or radial oxygen swap (stream reaeration) cathodes during considerably prolonged operation (206 days). Results show that the oxygen diffusing from cathode chamber to anode chamber can accelerate the degradation of organic matter in anode chamber to some extent, and weaken the electricity generation of MFC. The electrogenesis for the radial oxygen swap cathode MFC (OSCMFC) is superior to air aeration cathode MFC (AACMFC), with the maximum voltage and power density of 0.855 V and 3.954 W m−3, respectively. Compared with radial oxygen swap, air aeration causes more oxygen diffusion from cathode to anode chamber, which facilitates the growth of facultative anaerobes to accelerate the hydrolysis and acidification of the substrate and inhibits the activities of electricigens, resulting in the redox reaction of the oxygen and electrons in micro scales. The inhibiting effect of oxygen diffusion on electrogenic bacteria results in that a fraction of hydrolyzed organic matters is not converted into electricity, but rather to be devoured by non-electrogenic bacteria for the self-metabolic consumption and reproduction.

Potential of core-shell NiFe layered double hydroxide@Co3O4 nanostructures as cathode catalysts for oxygen reduction reaction in microbial fuel cells

To improve the activity of oxygen reduction reaction (ORR) of microbial fuel cell (MFC), the cathode was modified by using NiFe layered double hydroxide (LDH)@Co3O4 as catalyst to increase the power generation of MFC. The unique NiFe-LDH@Co3O4 core-shell structure was prepared by using NiFe-LDH as metal source, Co3O4 as support matrix and urea-doped nitrogen in LDH. XRD, FTIR, SEM and EDS showed that LDH was successfully grown on the surface of Co3O4, and had typical LDH nanostructure. The voltage output of NiFe-LDH@Co3O4-MFC was maintained at about 0.43 V, with insignificant variations over 8 d, which indicated that NiFe-LDH@Co3O4 catalyst has remarkable stability and durability. Moreover, the maximum power density was 467.35 ± 8.27 mW/m2, which was produced by NiFe-LDH@Co3O4. The results implied that the improvement of ORR activity of NiFe-LDH@Co3O4 was due to its high conductivity and abundant active sites, and therefore, the power generation capacity of MFC was improved. The electrode prepared by NiFe-LDH@Co3O4 modified air cathode was a promising material for fuel cell.

Adding Zero-Valent Iron to Enhance Electricity Generation during MFC Start-Up.

The low power generation efficiency of microbial fuel cells (MFCs) is always a barrier to further development. An attempt to enhance the start-up and electricity generation of MFCs was investigated by adding different doses of zero-valent iron into anaerobic anode chambers in this study. The results showed that the voltage (289.6 mV) of A2 with 0.5 g of zero-valent iron added was higher than the reference reactor (197.1 mV) without dosing zero-valent iron (A4). The maximum power density of 27.3 mW/m2 was obtained in A2. CV analysis demonstrated that A2 possessed a higher oxidation–reduction potential, hence showing a stronger oxidizing property. Meanwhile, electrochemical impedance analysis (EIS) also manifested that values of RCT of carbon felts with zero-valent iron supplemented (0.01–0.03 Ω) were generally lower. What is more, SEM images further proved and illustrated that A2 had compact and dense meshes with a hierarchical structure rather than a relatively looser biofilm in the other reactors. High-throughput sequencing analysis also indicated that zero-valent iron increased the abundance of some functional microbial communities, such as Acinetobacter, Ignavibacteriales, Shewanella, etc.

Electricity production of microbial fuel cells by degrading cellulose coupling with Cr(VI) removal

A facultative exoelectrogen strain Lsc-8 belonging to the Cellulomonas genus with the ability to degrade carboxymethyl cellulose (CMC) coupled with the reduction of Cr(VI), was successfully isolated from rumen content. The maximum output power density of the microbial fuel cells (MFCs) inoculated strain Lsc-8 was 9.56 ± 0.37 mW·m-2 with CMC as the sole carbon source. From the biomass analysis it can be seen that the electricity generation of the MFCs was primarily attributed to the planktonic cells of strain Lsc-8 rather than the biofilm attached on the electrode, which was different from Geobacter sulfurreducens. Especially, during electricity generation of the MFCs using CMC as carbon source in the anode chamber, the Cr(VI) reduction were simultaneously realized. And it is also found that the Cr(VI) reduction ratio by strain Lsc-8 is directly related to the initial Cr(VI) concentration, and it increased with the increase of initial Cr(VI) concentration at first, then started to decrease when the Cr(VI) concentration was above 21 mg ·L-1. Meanwhile, the highest output power density of 3.47 ± 0.28 mW·m-2 was observed coupling with 95.22 ± 2.72 % of Cr(VI) reduction. These data suggested that the strain Lsc-8 could reduce high toxicity Cr(VI) to low toxicity Cr(III) coupled with electricity generation in MFCs with CMC as the carbon source. Our results also suggested that this study will provide a possibility to simultaneously degrade Cr(VI) and generate electricity by using cellulose as the carbon source via MFCs.

Fabrication of polyaniline nanocomposites as electrode material for power generation in microbial fuel cells

Industrial revolution and population growth has resulted in the creation of energy scarcity. It is high time that there should be an efficient technique or source to derive sustaining electrical energy. Recent studies show that electrical energy can be generated using waste material through the fabrication of Microbial Fuel Cell (MFC). This study includes the fabrication of new MFC electrodes with nanocomposite coating in which the base material is a conducting polymer polyaniline (PANI). PANI is a highly conductive polymer and its nanocomposites will enhance the surface area of the electrodes and act as an efficient electro-catalyst. For the analysis, we had synthesized PANI, PANI - ZnO, and PANI - Cu/ZnO by methods of chemical polymerization, in-situ polymerization respectively. ZnO and Cu/ZnO nanoparticles were synthesized by co-precipitation method. The prepared samples were characterized by XRD analysis, FTIR analysis and UV–Visible spectroscopy. We have successfully fabricated dual chambered MFC using polyaniline nanocomposites coated electrodes and comparative study has been done for the power generation in MFC using these electrodes.

The Effect of Total Suspended Solids on the Electricity Generation in Microbial Fuel Cell Treating Actual Potato Chips Processing Wastewater

This study aimed to investigate the effect of total suspended solids (TSS) on the performance of a continuously operated dual-chamber microbial fuel cell (MFC) proceeded by primary clarifier to treat actual potato chips processing wastewater. The system was also tested in the absence of the primary clarifier and the results demonstrated a significant effect of TSS on the polarization curve of the MFC which was obtained by operating the graphite anodic electrode against Ag/AgCl reference electrode. The maximum observed power and current densities were decreased form 102.42 mW/m2 and 447.26 mA/m2 to 80.16 mW/m2 and 299.10 mA/m2, respectively due to the adverse effect of TSS. Also, the internal resistance increased from 40 to 70Ω.

Enhancing oxygen reduction reaction by using metal-free nitrogen-doped carbon black as cathode catalysts in microbial fuel cells treating wastewater

Microbial fuel cells (MFCs) is promising to combat environmental pollution by converting organic waste to electricity. One critical problem for practical application of MFCs treating wastewater is sluggish oxygen reduction reaction (ORR) on cathode. This study focused on developing novel metal-free cost-effective cathodic catalysts to enhance power generation of MFCs. Specifically, carbon powder (Vulcan XC-72R) was modified with acid treatment and pyrazinamide (as nitrogen precursor), and subsequently pyrolyzed at different temperatures. For CN-X (X=700-1000°C) materials, chemical compositions (the doping contents of nitrogen species, oxygen-containing groups, and sulfur-containing groups) were altered with pyrolysis temperature. Linear sweep voltammetry showed that CN-800 exhibited the highest ORR activity, with an onset potential of 0.215V and a half-wave potential of -0.096V (vs. Ag/AgCl). Electrochemical measurements clearly presented an enhancement of ORR activity by treating carbon powder with sulfuric acid and nitrogen doping, which was well correlated with voltage output in single chamber MFCs (SCMFCs). On the other hand, for the nitrogen-doped cathode catalysts, the best performance in SCMFCs was directly related with the amount of pyridinic nitrogen species and total nitrogen amount. The MFC operated with CN-800 exhibited a maximum power density of 371±3mW/m2 with the chemical oxygen demand (COD) removal of 77.2±1.5% and coulombic efficiency (CE) of 8.6±0.3%. Furthermore, the MFC with CN-800 exhibited an excellent stability over longer than 580h of operation with 1.5% voltage reduction. CN-800 possessed comparable COD removal efficiency to conventional costly Pt/C, and exhibited distinct cost-effectiveness for MFC practical applications in wastewater treatment.