Activity Of Microbial Fuel Cell Research Articles

Enrichment Media Selection and Co-Culture Potential among Exoelectrogen Bacteria Vary with Ecological Factors

Staphylococcus saprophyticus ICBB 9554 and Citrobacter freundii ICBB 9763 are exoelectrogen bacteria applied as microbial fuel cells (MFC). We selected enrichment media for both these exoelectrogen bacteria, characterized their synergistic traits, and evaluated the growth conditions under different ecological factors. In this study, different enrichment media, such as those containing sugar, molasses, and palm sugar (2, 4, and 6% w/v) were tested for S. saprophyticus ICBB 9554. Meanwhile, technical sodium acetate (NaAc), commercial vinegar 25%, and cider vinegar (5, 10, and 15 mM acetate concentration) were tested for C. freundii ICBB 9763. Both the exoelectrogen bacteria were tested for the synergistic trait by inhibitory test, metabolic activity, and electricity generation performance in MFC. Different ecological factors, including salinity (2, 3, and 4 dS/m), culture media pH (5.8, 6.5, and 6.9), and temperature (20 °C, 27 °C, and 31 °C) were investigated for bacterial growth. The selective enrichment medium ingredient for S. saprophyticus ICBB 9554 was 2% molasses while that for C. freundii ICBB 9763 was 0.05 M technical sodium acetate. Both bacteria were suspected to grow synergistically and could be inoculated simultaneously as a co-culture in MFC. The effect of different ecological factors indicated that co-culture could grow better than pure culture. This study's findings provide important data on potential enrichment media for exoelectrogen bacteria that are beneficial for scale-up to reduce the operational cost.

Poly (acrylamide-co-acrylonitrile) hydrogel-derived iron-doped carbon foam electrocatalyst for enhancing oxygen reduction reaction in microbial fuel cell

Developing advanced non-precious metal catalysts for oxygen reduction reaction (ORR) is critical for microbial fuel cells (MFCs). Fe–N–C catalysts are considered the best successor to platinum-based catalysts for ORR. Herein, we have synthesized environmental friendly, cost-effective Fe–N-doped carbon foam catalyst [Fe-embedded poly (acrylamide-co-acrylonitrile) hydrogel-based carbon foam(Fe@Am-co-An/CF)] by using Fe-embedded poly (Am-co-An) hydrogel for MFCs. Poly(Am-co-An) hydrogel is used as a carbon and nitrogen precursor. The synthesized catalysts are characterized by FTIR, SEM, TEM, XRD and XPS. Furthermore, four different catalysts based on different ratios of the metal such as Fe@Am-co-An/CF (1:22), Fe@Am-co-An/CF (2:22), Fe@Am-co-An/CF (3:22), and Am-co-An/CF have been prepared. Results indicate that the Fe@Am-co-An/CF (2:22) catalyst exhibits the highest power density (736.06 mWm−2 at the current density of 1132.04 mAm−2) compared to the other catalysts. The results of CV, LSV, EIS, and chronoamperometry indicate that Fe@Am-co-An/CF (2:22) is the most promising catalyst for ORR activity in MFCs.

Nitrogen-doped graphene oxide with enhanced bioelectricity generation from microbial fuel cells for marine sewage treatment

With the increasing demand for clean water and energy, microbial fuel cell (MFC) as a promising technology for obtaining energy from wastewater has attracted great research interest in the last two decades. The performance of the anode electrode is the most critical factor limiting the large-scale application of MFC. Graphene materials as a suitable candidate have been successfully used as the anode due to their excellent biocompatibility and efficient extracellular electron transfer (EET) ability. Here, nitrogen-doped graphene oxide (NGO) was prepared by a simple one-step hydrothermal method. X-ray photoelectron spectroscopy (XPS) was used to analyse the valence states of the surface chemical elements and their associated molecular species. Fourier transform infrared spectroscopy (FTIR) was used to identify the surface functional groups, and Raman spectroscopy was used to analyse the information about surface defects. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) revealed the increased electrochemical activity and rapid EET ability from the NGO electrodes. Scanning electron microscopy demonstrated the two-dimensional layered structure of the NGO with some wrinkled texture. MFCs equipped with the modified NGO anode achieved the highest power density of 708.3 mW/m2 with an output voltage of 498.6 mV in comparison with the other graphene-based electrodes, i.e., graphene and graphene oxide. Moreover, the chemical oxygen demand (COD) removal rate increased significantly from 18.1% to 45.6%. The analysis of the bacterial community using a high-throughput sequencing indicated that the relative abundance of the electricigens increased on the NGO electrode biofilim, and the relative expression of ccoN gene coding cytochrome-c oxidase (Cco) was markedly up-regulated. These results demonstrated that NGO modification effectively enhanced the bio-electrocatalytic activity of MFC with improved wastewater treatment capacity.

Catalytic advancements in carbonaceous materials for bio-energy generation in microbial fuel cells: a review.

Microbial fuel cells (MFCs) are a sustainable alternative for wastewater treatment and clean energy generation. The efficiency of the technology is dependent on the cathodic oxygen reduction reaction, where the sluggish reaction kinetics hampers its propensity. Carbonaceous materials with high electrical conductivity have been widely explored for oxygen reduction reaction (ORR) catalysts. Here, incorporating transition metal (TM) and heteroatom into carbon could further enhance the ORR activity and power generation in MFCs. Nitrogen (N)-doped carbons have also been a popular research hotspot due to abundant active sites formed, resulting in superior conductivity, stability, and catalytic activity over carbons. This review summarizes the progress in the carbon-based materials (primary focus on the cathode) for ORR and their utilization in MFCs. Furthermore, we discussed the conceptualization of MFCs and carbonaceous materials to instigate the ORR kinetics and power generation in MFC. Furthermore, prospects of carbon-based materials for actual application in bio-energy generation have been discussed. Carbonaceous catalysts and biomass-derived carbons exhibit good potential to replace precious Pt catalysts for ORR. M-N-C catalysts were found to be the most suitable catalysts. Electrocatalysts with MNx sites are able to achieve excellent activity and high-power output by taking advantage of the active site exposure and rapid mass transfer rate. Moreover, the use of biomass-derived carbons/self-doped carbons could further reduce the overall cost of catalysts. It is anticipated that the research gaps and future perspectives discussed will show new avenues to develop excellent electrocatalysts for better performance and transformation of technology to industrial applications.

A freestanding carbon submicro fiber sponge as high-efficient bioelectrochemical anode for wastewater energy recovery and treatment

Microbial fuel cells (MFCs), as a typical kind of microbial electrochemical technologies (METs), can achieve energy recovery and wastewater treatment. Microbial adhesion on electrodes directly affects microbe-electrode interactions, determining the performance of electricity generation and organic degradation. The anode with suitable structure and operation mode can reduce the limitation of fiber diameter-structure-interface trade-off to enhance microbe-electrode interaction. Here, we fabricated a carbon submicro fiber sponge with fiber diameter close to the size of electrogenic microorganism and operated it in filtration mode to greatly improve energy conversion. The carbon submicro fiber sponge exhibits a superior current yield of 17.4 A m−2 in the polarization curve with high electrochemical activity in MFC, which is 74% higher than that of the commonly used carbon fiber cloth anode. A higher chemical oxygen demand removal rate of 2.9 kg m−3 d−1 is obtained with this novel anode (1.3-fold that of the benchmark). The linkage mechanism of electricity generation and organic degradation is analyzed. Moreover, a long-term stability is demonstrated with excellent current production after the operation over 2 years. Our results indicate that this carbon fiber sponge has remarkable application potential in microbial electrochemical technologies for energy recovery from wastewater.

A pyridine-Fe gel with an ultralow-loading Pt derivative as ORR catalyst in microbial fuel cells with long-term stability and high output voltage

A low-cost and high-efficiency oxygen reduction reaction (ORR) catalyst was fabricated using a pyridine-Fe gel with ultralow-loading of Pt nanoparticles and subsequently applied to air-cathode microbial fuel cells (MFCs). This novel catalyst (N3/Fe/C-Pt) exhibited excellent electrocatalytic activity with a positive onset potential of 0.19 V (vs Ag/AgCl) and half-wave potential of 0.03 V (vs Ag/AgCl), which is comparable to commercial PtC catalysts. More importantly, N3/Fe/C-Pt shows remarkable oxygen reduction activity in MFCs with a distinct output voltage (568 mV) and power density (504 mW m−2) for 400 h when it is fed with a culture medium containing 5 g L−1 sucrose in the phosphate buffer solution. This strategy, incorporating Pt nanoparticles uniformly into a conductive gel demonstrates significance for broadening the development and research of gel-based catalysts for applications in batteries.

Bioelectric Activity of Microbial Fuel Cell during Treatment of Old Corrugated Containerboard Discharges

The bioelectric activity of two lab scale microbial fuel cell (MFC) designs, MFCI (1,500 cm3) and MFCII (12,000 cm3) were examined using old corrugated containerboard (OCC) discharge for simultaneous effective treatment with greater power production. The decrease of MFC internal resistance (MFC-Rin) resulted in increased generated power output. The different parameters used in MFC included electrode conducting area (ECA), cathodic redox solution (CRS), MFC volume capacity, and MFCs connections. The generated current densities (CD) and power densities output (PD) at variables of external resistances (Rex) that ranged from 10 Ω to 20,000 Ω were calculated to estimate the MFC-Rin. In MFCI, using potassium ferri-cyanide as CRS, the change of ECA from 16 cm2 to 64 cm2 decreased the MFCI-Rin from 130 Ω to 110 Ω, and it was further decreased to 65 Ω when manganese dioxide was used as the CRS. Using Rex 100 Ω, MFCII exhibited lower Rin 18.46%, enhanced voltage 37.5%, and greater chemical oxygen demand removal 4.77% compared with MFCI. Series and parallel connections between four MFCI increased the generated PD by 286% and 258%, respectively, compared with that obtained by single MFCI.

Enhanced performance of microbial fuel cell using carbon microspheres modified graphite anode

AbstractIn the present work, dual‐chamber microbial fuel cell (MFC) was constructed, in which anaerobic sludge was used as the inoculum and potassium ferricyanide as the electron acceptor. We have investigated the untapped potential of carbon microspheres modified graphite anode (CGA) fabricated by hydrothermal and calcinations method in the MFCs operation. The results showed that the CGA could be utilized as a novel and efficient MFC anode. The output power of the MFC involved with CGA is approximately 358 mW·m−2, which is 3.1 times of the counterpart MFC with graphite anode (GA). Furthermore, this MFC showed a 68% chemical oxygen demand (COD) removal rate of the wastewater. Through further analysis, the CGA could improve the specific surface area and enhance the adsorption of microorganism, which could efficiently favor the electron transfer rate between the microorganism and external circuit, resulting in the increase of the electrochemical activity of MFC.

Improving performance of microbial fuel cell while controlling methanogenesis by Chaetoceros pretreatment of anodic inoculum

Loss of substrate due to methanogenesis reduces Coulombic efficiency (CE) of the microbial fuel cell (MFC) significantly. Hexadecatrienoic acid present in the marine algae Chaetoceros inhibits the growth of methanogenic archaea. Influence of Chaetoceros pre-treated mixed anaerobic sludge on the electrogenic activity of MFC was evaluated. A MFC inoculated with Chaetoceros pre-treated mixed anaerobic sludge demonstrated maximum CE of 45.18%, with volumetric power density of 21.43W/m3 and current density of 93A/m3. Cyclic voltammetry indicated higher electron discharge on the anode surface due to suppression of methanogenesis. Tafel analysis also showed a higher exchange current density and a lower Tafel slope and charge transfer resistance, indicating advantage of this pre-treatment method in reducing the cell internal losses. A 60% reduction in specific methanogenic activity was observed in anaerobic sludge pre-treated with Chaetoceros; emphasizing significance of this pretreatment for suppressing methanogenesis and its utility for enhancing electricity generation in MFC.

Employing a Central Composite Rotatable Design to Define and Determine Significant Toxic Levels of Heavy Metals on Shewanella putrefaciens in Microbial Fuel Cell

Microbial fuel cells (MFCs) are a unique technology that takes advantage of bacterial metabolism to generate electricity and remove chemical oxygen demand (COD) from organic pollutants. Existence of heavy metals in fuel affects vitally bacterial activity in MFC. Present study aimed to define the negative effect of three most toxic heavy metals, namely mercury (HgCl2), lead (Pb(NO3)2), and cadmium (CdCl2), on the activity of bacterium Shewanella putrefaciens with respect to electricity generation and COD removal in MFC from food industry wastewater. A central composite rotatable design was employed to determine the significant toxic levels of used heavy metals. The results indicted that the main effect of HgCl2, Pb(NO3)2, and CdCl2 was −62.17, −58.55, and −31.65 %, respectively, with respect to electricity generation, as well as −34.32, −32.25, and −18.95 %, respectively, with respect to COD removal, at 95 % confidence. The statistical design determined the significant toxic levels for each factor of heavy metals alone as (mg/100 mL) HgCl2 23.45, Pb(NO3)2 34.38, and CdCl2 48.31, with respect to electricity generation, as well as 26.34, 31.84, and 52.56, respectively, with regard to COD removal at 95 % confidence. The coefficient of determination (R2) was found to be 0.93 and 0.98 for electricity generation and COD removal, respectively. The confirmatory experiments showed closeness of predicted and observed values.

Air-cathode microbial fuel cell array: A device for identifying and characterizing electrochemically active microbes

Microbial fuel cells (MFCs) have generated excitement in environmental and bioenergy communities due to their potential for coupling wastewater treatment with energy generation and powering diverse devices. The pursuit of strategies such as improving microbial cultivation practices and optimizing MFC devices has increased power generating capacities of MFCs. However, surprisingly few microbial species with electrochemical activity in MFCs have been identified because current devices do not support parallel analyses or high throughput screening. We have recently demonstrated the feasibility of using advanced microfabrication methods to fabricate an MFC microarray. Here, we extend these studies by demonstrating a microfabricated air-cathode MFC array system. The system contains 24 individual air-cathode MFCs integrated onto a single chip. The device enables the direct and parallel comparison of different microbes loaded onto the array. Environmental samples were used to validate the utility of the air-cathode MFC array system and two previously identified isolates, 7Ca ( Shewanella sp.) and 3C ( Arthrobacter sp.), were shown to display enhanced electrochemical activities of 2.69 mW/m 2 and 1.86 mW/m 2, respectively. Experiments using a large scale conventional air-cathode MFC validated these findings. The parallel air-cathode MFC array system demonstrated here is expected to promote and accelerate the discovery and characterization of electrochemically active microbes.