Leonor Morgado, Joana M. Dantas, Telma Simões et al.

Bioscience Reports • 2013

The bacterium Gs (Geobacter sulfurreducens) is capable of oxidizing a large variety of compounds relaying electrons out of the cytoplasm and across the membranes in a process designated as extracellular electron transfer. The trihaem cytochrome PpcA is highly abundant in Gs and is most probably the reservoir of electrons destined for the outer surface. In addition to its role in electron transfer pathways, we have previously shown that this protein could perform e−/H+ energy transduction. This mechanism is achieved by selecting the specific redox states that the protein can access during the redox cycle and might be related to the formation of proton electrochemical potential gradient across the periplasmic membrane. The regulatory role of haem III in the functional mechanism of PpcA was probed by replacing Met58, a residue that controls the solvent accessibility of haem III, with serine, aspartic acid, asparagine or lysine. The data obtained from the mutants showed that the preferred e−/H+ transfer pathway observed for PpcA is strongly dependent on the reduction potential of haem III. It is striking to note that one residue can fine tune the redox states that can be accessed by the trihaem cytochrome enough to alter the functional pathways.

Akihiro Okamoto, Ryuhei Nakamura, Kenneth H. Nealson et al.

ChemElectroChem • 2014

AbstractCertain microbes are capable of transporting electrons from the cell interior‐respiratory electron chain to insoluble electron acceptors located outside of the cell, a process referred to as extracellular electron transport (EET). Bacteria capable of EET are currently utilized as “living anode catalysts” in microbial fuel cells. Several EET mechanisms have been proposed, yet they lack molecular‐level consistency. Here, we review our recent work, presenting a “bound‐flavin cofactor” model, which we believe provides a suitable explanation for all of the published data to date for the model EET microbes of Shewanella oneidensis and Geobacter sulfurreducens. We discuss the interaction between free flavin and outer‐membrane c‐type cytochromes based on a protein–ligand binding model, the accumulation of cell‐secreted flavins in nanostructured electrodes, and EET through intermittent direct contacts or conductive extracellular appendages.

Jessica E Butler, Nelson D Young, Derek R Lovley

BMC Genomics • 2010

Geobacter species grow by transferring electrons out of the cell--either to Fe(III)-oxides or to man-made substances like energy-harvesting electrodes. Study of Geobacter sulfurreducens has shown that TCA cycle enzymes, inner-membrane respiratory enzymes, and periplasmic and outer-membrane cytochromes are required. Here we present comparative analysis of six Geobacter genomes, including species from the clade that predominates in the subsurface. Conservation of proteins across the genomes was determined to better understand the evolution of Geobacter species and to create a metabolic model applicable to subsurface environments.

Gemma Reguera

Biochemical Society Transactions • 2012

The in situ stimulation of Fe(III) oxide reduction in the subsurface stimulates the growth of Geobacter spp. and the precipitation of U(VI) from groundwater. As with Fe(III) oxide reduction, the reduction of uranium by Geobacter spp. requires the expression of their conductive pili. The pili bind the soluble uranium and catalyse its extracellular reductive precipitation along the pili filaments as a mononuclear U(IV) complexed by carbon-containing ligands. Although most of the uranium is immobilized by the pili, some uranium deposits are also observed in discreet regions of the outer membrane, consistent with the participation of redox-active foci, presumably c-type cytochromes, in the extracellular reduction of uranium. It is unlikely that cytochromes released from the outer membrane could associate with the pili and contribute to the catalysis, because scanning tunnelling microscopy spectroscopy did not reveal any haem-specific electronic features in the pili, but, rather, showed topographic and electronic features intrinsic to the pilus shaft. Pili not only enhance the rate and extent of uranium reduction per cell, but also prevent the uranium from traversing the outer membrane and mineralizing the cell envelope. As a result, pili expression preserves the essential respiratory activities of the cell envelope and the cell's viability. Hence the results support a model in which the conductive pili function as the primary mechanism for the reduction of uranium and cellular protection in Geobacter spp.

S. Veer Raghavulu, P.N. Sarma, S. Venkata Mohan

Journal of Applied Microbiology • 2011

To study the bioelectrochemical behaviour of Pseudomonas aeruginosa (MTCC 17702) and Escherichia coli (MTCC 10436) and to assess their potential to act as anodic biocatalyst with the function of anaerobic consortia for microbial (bio) fuel cell (BFC) application.

Kengo Sasaki, Masahiko Morita, Norio Matsumoto et al.

Journal of Bioscience and Bioengineering • 2012

The aim of this study was to show the effectiveness of the membrane free bioelectrochemical system (BES) using three electrodes on inhibition of methanogenesis and construction of hydrogen fermentation from the artificial garbage slurry. The electrical redox-potential on the working electrode was adjusted to -1.0V (vs. Ag/AgCl) that has positive effect on methanogenesis. The redox-potential on the counter electrode was measured to be 1.6V. The pH in the effluents was 5.5-6.4. Hydrogen production rate at the cathode side was similar to that at the anode side and much higher than that calculated from current, and reached a maximum of 2445±815 (average±standard deviation) mL L(-1) d(-1) at an organic loading rate of 58.7g dichromate chemical oxygen demand per L d(-1). Methane production was negligible throughout the experiment. Acetate and butyrate were the main products of the fermentation using a BES; these offered favorable conditions for hydrogen production. The bacterial community in the bioelectrochemical hydrogen fermentor differed from that in the methanogenic seed sludge and included hitherto unknown species. These results show that high redox-potential on the anodic electrode and acidic pH in the membrane free BES can be utilized for hydrogen fermentation from the artificial garbage slurry by avoiding methanogenesis.

Iain S. Michie, Jung Rae Kim, Richard M. Dinsdale et al.

Bioresource Technology • 2014

In this study three different tubular helical anode designs are compared, for each helical design the pitch and nominal sectional area/liquid flow channel between the helicoids was varied and this produced maximum power densities of 11.63, 9.2 and 6.73Wm(-3) (small, medium and large helical flow channel cross-sections). It is found that the level of mixing and the associated shear rates present in the anodes affects both the power development and biofilm formation. The small helical flow channel carbon anode produced 40% more biofilm and this result was related to modelling data which determined a system shear rate of 237s(-1), compared to 52s(-1) and 47s(-1) for the other reactor configurations. The results from computational fluid dynamic modelling further distinguishes between convective flow conditions and supports the influence of helical structure on system performance, so establishing the importance of anodic design on the overall electrogenic biofilm activity.

Stephen J. Andersen, Ilje Pikaar, Stefano Freguia et al.

Environmental Science & Technology • 2013

Microbial bioelectrochemical systems (BESs) use microorganisms as catalysts for electrode reactions. They have emerging applications in bioenergy, bioproduction, and bioremediation. BESs can be scaled up as a linked series of units or cells; however, this may lead to so-called cell reversal. Here, we demonstrate a cell balance system (CBS) that controls individual BES cells connected electrically in series by dynamically adapting the applied potential in the kilohertz frequency range relative to the performance of the bioanode. The CBS maintains the cell voltage of individual BES cells at or below a maximum set point by bypassing a portion of applied current with a high-frequency metal oxide semiconductor field-effect transistor switch control system. We demonstrate (i) multiple serially connected BES cells started simultaneously and rapidly from a single power source, as the CBS imparts no current limitation, (ii) continuous, stable, and independent performance of each stacked BES cell, and (iii) stable BES cell and stack performance under excessive applied currents. This control system has applications for not only serially stacked BESs in scaled-up stacks but also rapidly starting individual- and/or lab-scale BESs.

Ahmed ElMekawy, Sandipam Srikanth, Karolien Vanbroekhoven et al.

Journal of Power Sources • 2014

Deyong Kong, Bin Liang, Duu-Jong Lee et al.

Journal of Environmental Sciences • 2014

Exposure to chloramphenicol (CAP), a chlorinated nitroaromatic antibiotic, can induce CAP-resistant bacteria/genes in diverse environments. A biocathode bioelectrochemical system (BES) was applied to reduce CAP under switched operational temperatures. When switching from 25 to 10°C, the CAP reduction rate (kCAP) and the maximum amount of the dechlorinated reduced amine product (AMCl, with no antibacterial activity) by the biocathode communities were both markedly decreased. The acetate and ethanol yield from cathodophilic microbial glucose fermentation (with release of electrons) was also reduced. Formation of the product AMCl was enhanced by the biocathode dechloridation reaction compared with that produced from pure electrochemical or microbial dechloridation processes. The electrochemical and morphological analyses of cathode biofilms demonstrated that some cathodophilic microbes could adapt to low temperature and play a key role in CAP degradation. The resilient biocathode BES has a potential for the treatment of CAP-containing wastewater in temperature fluctuating environments.

Sanath Kondaveeti, Sang-Hoon Lee, Hee-Deung Park et al.

Water Research • 2014

Pan Yu Wong, Ka Yu Cheng, Anna H. Kaksonen et al.

Water Research • 2014

We demonstrated the ability of a bio-anode to fix dinitrogen (N2), and confirmed that diazotrophs can be used to treat N-deficient wastewater in a bioelectrochemical system (BES). A two-compartment BES was fed with an N-deficient medium containing glucose for >200 days. The average glucose and COD removal at an anodic potential of +200 mV vs. Ag/AgCl was 100% and 76%, respectively. Glucose removal occurred via fermentation under open circuit (OC), with acetate as the key byproduct. Closing circuit remarkably reduced acetate accumulation, suggesting the biofilm could oxidise acetate under N-deficient conditions. Nitrogen fixation required an anode and glucose; removing either reduced N2 fixation significantly. This suggests that diazotroph utilised glucose directly at the anode or indirectly through syntrophic interaction of an N2-fixing fermenter and an anodophile. The enriched biofilm was dominated (68%) by the genus Clostridium, members of which are known to be electrochemically active and capable of fixing N2.

Tao Bo, Lixia Zhang, Xiaoyu Zhu et al.

RSC Adv. • 2014

Nikolaos Xafenias, Valeria Mapelli

International Journal of Hydrogen Energy • 2014

Fanying Kong, Aijie Wang, Hong-Yu Ren

Bioresource Technology • 2014

This study developed and optimized a modular biocathode materials design in bioelectrochemical system (BES) using composite metal and carbon-based materials. The 4-chlorophenol (4-CP) dechlorination could be improved with such composite materials. Results showed that stainless steel basket (SSB) filled with graphite granules (GG) and carbon brush (CB) (SSB/GG/CB) was optimum for dechlorination, followed by SSB/CB and SSB/GG, with rate constant k of 0.0418 ± 0.0002, 0.0374 ± 0.0004, and 0.0239 ± 0.0002 h(-1), respectively. Electrochemical impedance spectroscopy (EIS) demonstrated that the composite materials with metal can benefit the electron transfer and decrease the charge transfer resistance to be 80.4 Ω in BES-SSB/GG/CB, much lower than that in BES-SSB (1674.3 Ω), BES-GG (387.3 Ω), and BES-CB (193.8 Ω). This modular cathode design would be scalable with successive modules for BES scale-up, and may offer useful information to guide the selection and design of BES materials towards dechlorination improvement in wastewater treatment.

Fei Sun, Hao Liu, Bin Liang et al.

Bioresource Technology • 2013

Reductive degradation of choramphenicol (CAP) using Bioelectrochemical system (BES) with both abiotic cathode and biocathode was investigated. It was found that the CAP reduction efficiency during the first 24 h reached 86.3% of the biocathode group, while which was only 62.9% in the case of abiotic cathode. Except for the cathode potential, other indicators of the cathode performance as the cathode current, the current response of the cyclic voltammetry, the ohm resistance, and the polarization resistance of the biocathode group were all better than those of the abiotic group. Moreover, specific CAP reductive rate of the biocathode with sludge fermentation liquid (0.199 h(-1)) as carbon source was close to that of the glucose (0.215 h(-1)), but was about 3.2 times of the abiotic cathode group (0.062 h(-1)). It suggested that the introduction of biocathode would better the cathode performance, and then further increase the CAP reduction.

Li Xiao, Erica B. Young, John A. Berges et al.

Environmental Science & Technology • 2012

An integrated photobioelectrochemical (IPB) system was developed by installing a microbial fuel cell (MFC) inside an algal bioreactor. This system achieves the simultaneous removal from a synthetic solution of organics (in the MFC) and nutrients (in the algal bioreactor), and the production of bioenergy in electricity and algal biomass through bioelectrochemical and microbiological processes. During the one-year operation, the IPB system removed more than 92% of chemical oxygen demand, 98% of ammonium nitrogen, and 82% of phosphate and produced a maximum power density of 2.2 W/m(3) and 128 mg/L of algal biomass. The algal growth provided dissolved oxygen to the cathode reaction of the MFC, whereas electrochemical oxygen reduction on the MFC cathode buffered the pH of the algal growth medium (which was also the catholyte). The system performance was affected by illumination and dissolved oxygen. Initial energy analysis showed that the IPB system could theoretically produce enough energy to cover its consumption; however, further improvement of electricity production is desired. An analysis of the attached and suspended microbes in the cathode revealed diverse bacterial taxa typical of aquatic and soil bacterial communities with functional roles in contaminant degradation and nutrient cycling.

S. Srikanth, M. Venkateswar Reddy, S. Venkata Mohan

Bioresource Technology • 2012

Microaerophilic microenvironment at biocathode was evaluated for electrogenesis along with the polyhydroxyalkanoates (PHA) accumulation in bio-electrochemical system (BES). The electrogenic activity (512 mV; 15.2 mW/m(2)) was extended for longer periods (144 h) which might be attributed to the lowering of losses due to the controlled microbial metabolism. Growth limiting stress at cathode due to lower oxygen levels and its effective utilization by the protons and electrons coming from anode, might have diverted the microbial metabolism towards PHA synthesis instead of oxidation. PHA accumulation (19% of dry cell weight (DCW)) was observed with higher hydroxy butyrate (HB) (89%) concentration at 48 th h in the cathodic biocatalyst and was re-utilized by the end of experiment. Bio-electro kinetics studied through voltammetry and Tafel analysis further supported the observed electrogenesis in microaerophilic reduction microenvironment, in terms of redox catalytic currents, Tafel slopes, exchange current densities and polarization resistance.

Suyun Zeng, Sujun Wang, Li Wang et al.

Sensors • 2012

CD105 is a well-known tumor metastasis marker and useful for early monitoring of metastasis and cancer relapse. It is important to generate rapid, reliable and precise analytical information regarding CD105 levels. To establish a simple, selective and sensitive detection method, we prepared an immunosensor with novel bioconjugates based on Pt nanoparticles, thionin acetate and antibodies. The proposed immunosensor displayed a broader linear response to CD105, with a working range of 1.3 to 200.0 ng/mL and a detection limit of 0.9 ng/mL under optimal conditions. Moreover, the studied immunosensor exhibited high sensitivity, fast analysis and adequate stability. The proposed methodology could readily be extended to other clinical- or environment-related biospecies.

Sanath Kondaveeti, Booki Min

Bioprocess and Biosystems Engineering • 2013

Electrochemical treatment of nitrate ions was attempted using different catalysts on the cathode in bioelectrochemical denitrification systems. The carbon cathode coated by biofilm (biocathode) could remove 91 % of nitrate ions at 1.0 V, which was almost same as the Pt-coated electrode (90 %). The exchange current density of biocathode was 0.0083 A/m(2), which was almost 22 times higher than with an abiotic plain carbon cathode. The formation of intermediate products in nitrate reduction varied depending on the cell voltage. At 0.5 V, a large portion of nitrate was converted to ammonia, but at more increased cell voltage (0.7 and 1 V) a high amount of nitrite ions was found with little ammonia formation in cathodic solution. The maximum nitrate removal rate was 0.204 mg NO(3)-N/cm(2)d by biocathode, while plain carbon paper showed only 0.176 mg NO(3)-N/cm(2)d. Electrochemical analysis of chronoamperometry showed a higher stable current generation for biocathode (3.1 mA) and Pt-coated cathode (2.8 mA) as compared to plain carbon (0.6 mA) at 0.7 V of poised voltage.

Sanath Kondaveeti, Sang-Hoon Lee, Hee-Deung Park et al.

Water Research • 2014

Electrochemical treatment of nitrate (NO3(-)), nitrite (NO2(-)) and mixtures of nitrate and nitrite was evaluated with microbial catalysts on a cathode in three different bioelectrochemical denitrification systems (BEDS). The removal rates and removal percentage of nitrogen (N) compounds varied during biotic and abiotic operations. The biotic cathode using NO3(-)-N as an electron acceptor showed enhanced removal percentages (88%) compared to the operation with NO2(-)-N (85%). The simultaneous reduction of NO3(-)-N and NO2(-)-N occurred in the operation with a mixture of N compounds. The bacterial diversity from the initial inoculum (return sludge) changed at the end of bioelectrochemical denitrification operation after 55 days. The microbial community composition was different depending on the type of electron acceptor. BEDS operation with NO3(-)-N and NO2(-)-N was enriched with Proteobacteria and Firmicutes respectively. BEDS with a mixture of N electron acceptors showed enrichment with Proteobacteria. There was no clear, distinct microbial community between the cathode biofilm and suspended biomass.

The Hai Pham, Peter Aelterman, Willy Verstraete

Trends in Biotechnology • 2009

In a bioelectrochemical system (BES) operated with a bioanode, the anode performance plays an important part in the overall performance. Fundamental aspects of bioanodes have been intensively investigated, enabling us to better understand the growth, kinetics functioning and interactions of anodophilic microorganisms. Recently, various technological advances have improved the properties and operation of anodes and have increased bioanode performance by up to tenfold. To further boost the performance of bioanodes by several orders of magnitude, practical microbiological approaches deserve more investigation. This article reviews the factors affecting bioanode performance, the recent advances and the prospective strategies for improving it. Future application perspectives of bioanodes are also proposed.

A. Bonmatí, A. Sotres, Y. Mu et al.

Bioresource Technology • 2013

The aim of this work was to investigate the feasibility of using oxalate at the anode in a continuous reactor. Complete oxalate removal was observed, albeit at a maximum coulombic efficiency of 33.9±0.4%. At the cathode side, there was an increase in pH from 8 to 11 showing production of caustic. Analysis of the microbial community demonstrated a clear shift during reactor start-up, resulting in enrichment of microorganisms belonging to Bacteroidetes, Firmicutes, Mollicutes, and β and γ-Proteobacteria. Methane was produced throughout the experiment; Archaea belonging to the Methanosarcinacea, Methanomicrobiaceae and Methanosaetaceae were identified as key representatives.

S. Venkata Mohan, S. Veer Raghavulu, P.N. Sarma

Biosensors and Bioelectronics • 2008

Biochemical functioning of single chambered microbial fuel cell (MFC) using glass wool as proton exchange membrane (PEM) operated with selectively enriched acidogenic mixed culture was evaluated in terms of bioelectricity production and wastewater treatment. Performance of MFC was studied at two different organic/substrate loading rates (OLR) (2.64 and 3.54 kg COD/m(3)) and operating pH 6 and 7 using non-coated plain graphite electrodes (mediatorless anode; air cathode). Applied OLR in association with operating pH showed marked influence on the power output and substrate degradation efficiency. Higher current density was observed at acidophilic conditions [pH 6; 98.13 mA/m(2) (2.64 kg COD/m(3)-day; 100 Omega) and 111.29 mA/m(2) (3.54 kg COD/m(3)-day; 100 Omega)] rather than neutral conditions [pH 7; 100.52 mA/m(2) (2.64 kg COD/m(3)-day; 100 Omega) and 98.13 mA/m(2) (3.54 kg COD/m(3)-day; 100 Omega)]. On the contrary, effective substrate degradation was observed at neutral pH. MFC performance was evaluated employing polarization curve, impedance analysis, cell potential, Coulombic efficiency and bioprocess monitoring. Sustainable power yield was calculated at stable cell potential.

Sunil A. Patil, Venkata Prasad Surakasi, Sandeep Koul et al.

Bioresource Technology • 2009

Feasibility of using chocolate industry wastewater as a substrate for electricity generation using activated sludge as a source of microorganisms was investigated in two-chambered microbial fuel cell. The maximum current generated with membrane and salt bridge MFCs was 3.02 and 2.3 A/m(2), respectively, at 100 ohms external resistance, whereas the maximum current generated in glucose powered MFC was 3.1 A/m(2). The use of chocolate industry wastewater in cathode chamber was promising with 4.1 mA current output. Significant reduction in COD, BOD, total solids and total dissolved solids of wastewater by 75%, 65%, 68%, 50%, respectively, indicated effective wastewater treatment in batch experiments. The 16S rDNA analysis of anode biofilm and suspended cells revealed predominance of beta-Proteobacteria clones with 50.6% followed by unclassified bacteria (9.9%), alpha-Proteobacteria (9.1%), other Proteobacteria (9%), Planctomycetes (5.8%), Firmicutes (4.9%), Nitrospora (3.3%), Spirochaetes (3.3%), Bacteroides (2.4%) and gamma-Proteobacteria (0.8%). Diverse bacterial groups represented as members of the anode chamber community.

S. Venkata Mohan, R. Saravanan, S. Veer Raghavulu et al.

Bioresource Technology • 2008

The performance of aerated and ferricyanide catholytes on the bioelectricity production was evaluated in dual chambered microbial fuel cell (MFC) (mediatroless anode; graphite electrodes) employing selectively enriched H(2) producing mixed consortia as anodic inoculum. Two MFCs with aerated catholyte (MFC(AC)) and ferricyanide catholyte (MFC(FC)) were operated separately to elucidate the difference in power generation potential and carbon removal efficiency under similar operating conditions [ambient pressure; room temperature (28+/-2 degrees C); acidophilic microenvironment (pH 6)]. The experimental data demonstrated the feasibility of in situ bioelectricity generation along with wastewater treatment. Effective power generation and substrate removal efficiency was documented in the fuel cell operated with ferricyanide catholyte (586 mV; 2.37 mA; 0.559 kg COD/m(3) day) than aerated catholyte (572 mV; 1.68 mA; 0.464 kg COD/m(3) day). Maximum power yield (0.635 W/kg COD(R) and 0.440 W/kg COD(R)) and current density (222.59 mA/m(2) and 190.28 mA/m(2)) was observed at 100 Omega resistor with ferricyanide and aerated catholytes, respectively. The study documented both wastewater treatment and electricity production through direct conversion of H(2) in a single system.

Anil Ghadge, M.M. Ghangrekar, Soumya Pandit et al.

International Journal of Environmental Technology and Management • 2014

Surajbhan Sevda, Xochitl Dominguez-Benetton, Karolien Vanbroekhoven et al.

Applied Energy • 2013

Ho Il Park, Chenjie Wu, Lian-Shin Lin

Biotechnology and Bioprocess Engineering • 2012

Olivier Lefebvre, Zi Tan, Yujia Shen et al.

Bioresource Technology • 2012

Microbial fuel cell (MFC) for wastewater treatment is still hindered by the prohibitive cost of cathode material, especially when platinum is used to catalyze oxygen reduction. In this study, recycled scrap metals could be used efficiently as cathode material in a specially-designed MFC. In terms of raw power, the scrap metals ranked as follows: W/Co > Cu/Ni > Inconel 718 > carpenter alloy; however, in terms of cost and long term stability, Inconel 718 was the preferred choice. Treatment performance--assessed on real and synthetic wastewater--was considerably improved either by filling the anode compartment with carbon granules or by operating the MFC in full-loop mode. The latter option allowed reaching 99.7% acetate removal while generating a maximum power of 36 W m(-3) at an acetate concentration of 2535 mg L(-1). Under these conditions, the energy produced by the system averaged 0.1 kWh m(-3) of wastewater treated.

Morio Miyahara, Kazuhito Hashimoto, Kazuya Watanabe

Journal of Bioscience and Bioengineering • 2013

Cassette-electrode microbial fuel cells (CE-MFCs) have been developed for the conversion of biomass wastes into electric energy. The present study modified CE-MFC for its application to wastewater treatment and examined its utility in a long-term (240 days) experiment to treat a synthetic wastewater, containing starch, yeast extract, peptone, plant oil, and a detergent (approximately 500 mg of total chemical oxygen demand [COD] per liter). A test MFC reactor (1 l in capacity) was equipped with 10 cassette electrodes with total anode and cathode projection areas of 1440 cm(2), and the operation was initiated by inoculating with rice paddy-field soil. It was demonstrated that CE-MFC achieved COD removal rates of 80% at hydraulic-retention times of 6 h or greater, and electricity was generated at a maximum power density of 150 mW m(-2) and Coulombic efficiency of 20%. Microbial communities established on anodes of CEs were analyzed by pyrosequencing of PCR-amplified 16S rRNA gene fragments, showing that Geobacter, Clostridium, and Geothrix were abundantly detected in anode biofilms. These results demonstrate the utility of CE-MFC for wastewater treatment, in which Geobacter and Geothrix would be involved in the electricity generation.

Krishna P. Katuri, Ann-Marie Enright, Vincent O'Flaherty et al.

Bioelectrochemistry • 2012

The ability of dual-chambered microbial fuel cell, fed with slaughterhouse wastewater with an anaerobic mixed-sludge as initial source of bacteria, to generate power is investigated. MFC voltage generation across a fixed 100 Ω load indicates power generation capability, with power production correlated to changes in anolyte VFA content. A maximum MFC power density of 578 mW/m(2) is obtained for an MFC developed under 100 Ω load, compared to a maximum power density of 277 mW/m(2) for an MFC developed under higher resistance (1 MΩ) control conditions. Voltammetry of the biofilm developed under 100 Ω load displays a current-voltage signal indicative of bioelectrocatalytic oxidation of feed at a potential of -0.35 V vs. Ag/AgCl, compared to negligible signals for biofilms developed under control conditions. Denaturing gradient gel electrophoresis of PCR amplified 16S rRNA gene fragments reveals that the anodic bacterial communities in reactors operated under 100 Ω load result in communities of lower diversity than for the control condition, with Geovibrio ferrireducens dominant in the anodic biofilm community. These results indicate that in MFC reactors, functionally stable electroactive bacteria are enriched under 100 Ω load compared to high resistance control conditions, and were able to sustain higher power in MFCs.

BK Pandey, V Mishra, S Agrawal

International Journal of Engineering, Science and Technology • 2011

Hong Liu, Ramanathan Ramnarayanan, Bruce E. Logan

Environmental Science & Technology • 2004

Microbial fuel cells (MFCs) have been used to produce electricity from different compounds, including acetate, lactate, and glucose. We demonstrate here that it is also possible to produce electricity in a MFC from domestic wastewater, while atthe same time accomplishing biological wastewater treatment (removal of chemical oxygen demand; COD). Tests were conducted using a single chamber microbial fuel cell (SCMFC) containing eight graphite electrodes (anodes) and a single air cathode. The system was operated under continuous flow conditions with primary clarifier effluent obtained from a local wastewater treatment plant. The prototype SCMFC reactor generated electrical power (maximum of 26 mW m(-2)) while removing up to 80% of the COD of the wastewater. Power output was proportional to the hydraulic retention time over a range of 3-33 h and to the influent wastewater strength over a range of 50-220 mg/L of COD. Current generation was controlled primarily by the efficiency of the cathode. Optimal cathode performance was obtained by allowing passive air flow rather than forced air flow (4.5-5.5 L/min). The Coulombic efficiency of the system, based on COD removal and current generation, was < 12% indicating a substantial fraction of the organic matter was lost without current generation. Bioreactors based on power generation in MFCs may represent a completely new approach to wastewater treatment. If power generation in these systems can be increased, MFC technology may provide a new method to offset wastewater treatment plant operating costs, making advanced wastewater treatment more affordable for both developing and industrialized nations.

Ramin Sedaqatvand, Mohsen Nasr Esfahany, Tayebeh Behzad et al.

Bioresource Technology • 2013

In this study, for the first time, the conduction-based model is extended, and then combined with Genetic Algorithm to estimate the design parameters of a MFC treating dairy wastewater. The optimized parameters are, then, validated. The estimated half-saturation potential of -0.13 V (vs. SHE) is in good agreement while the biofilm conductivity of 8.76×10(-4) mS cm(-1) is three orders of magnitude lower than that previously-reported for pure-culture biofilm. Simulations show that the ohmic and concentration overpotentials contribute almost equally in dropping cell voltage in which the concentration film and biofilm conductivity comprise the main resistances, respectively. Thus, polarization analysis and determining the controlling steps will be possible through that developed extension. This study introduces a reliable method to estimate the design parameters of a particular MFC and to characterize it.

Ya Li Zhan, Xuan Guo, Bei Bei Zheng et al.

Advanced Materials Research • 2012

A two-chambered MFC packed with activated carbon and used acrylic fiber wastewater as carbon source was constructed to study the electrical and anolyte change characteristics of the cell, the influence of activated carbon packing materials on electricity generation performance was analysed. The results indicated that microbial fuel cell could be upstart successfully when anaerobic sludge taken from wastewater treatment plants of acrylic fiber companies was used as inoculation; the maximum power density output of MFC was 211W/m3, and the internal resistance was 1311; N-contained aromatic compounds in anolyte was absorbed by activated carbon which made the cell could stably operated for a long time without renewing anolyte; anaerobic metabolism process was occurred in anode chamber, and during which N-contained aromatic compounds was degraded to amide, carboxylic acid, ammonia, etc.

Mohammad Mahdi Mardanpour, Mohsen Nasr Esfahany, Tayebeh Behzad et al.

Biosensors and Bioelectronics • 2012

This study reports on the fabrication of a novel annular single chamber microbial fuel cell (ASCMFC) with spiral anode. The stainless steel mesh anode with graphite coating was used as anode. Dairy wastewater, containing complex organic matter, was used as substrate. ASCMFC had been operated for 450 h and results indicated a high open circuit voltage (about 810 mV) compared with previously published results. The maximum power density of 20.2 W/m(3) obtained in this study is significantly greater than the power densities reported in previous studies. Besides, a maximum coulombic efficiency of 26.87% with 91% COD removal was achieved. Good bacterial adhesion on the spiral anode is clearly shown in SEM micrographs. High power density and a successful performance in wastewater treatment in ASCMFC suggest it as a promising alternative to conventional MFCs for power generation and wastewater treatment. ASCMFC performance as a power generator was characterized based on polarization behavior and cell potentials.

Nattakarn Prasertsung, Chavalit Ratanatamskul

Desalination and Water Treatment • 2013

Tyler Huggins Paul H Fallgren

Journal of Microbial & Biochemical Technology • 2013

S. Venkata Mohan, S. Srikanth, P.N. Sarma

Bioelectrochemistry • 2009

Single chambered mediatorless microbial fuel cell (MFC Nafion-117 membrane) fabricated with non-catalyzed electrodes was operated with open-air cathode to evaluate bioelectricity generation from domestic wastewater under acidogenic conditions (pH, 6) using anaerobic mixed consortia as anodic biocatalyst. Experimental data illustrated the feasibility of bioelectricity generation from domestic wastewater treatment. A steady increase in MFC performance was observed from the first cycle (0.248 V; 27.3 mW/m(2); 1.06 W/kg COD(R)) during the startup phase prior to stabilization on fourth cycle (0.449 V; 144.6 mW/m(2); 4.64 W/kg COD(R)). Sharp increase in power generation was observed after the fourth hour (125.4 mW/m(2); 289.61 mA/m(2)) which continued up to the sixth hour (155.92 mW/m(2); 325.51 mA/m(2)) and gradually decreased thereafter. Voltammogram evidenced clear redox peaks (E(0)', -0.334 V) related to redox mediator NAD(+)/NADH (E(0)', -0.32 V) suggesting a strong reducing phase. Higher energy (1.33 J) was observed at the fourth hour in concurrence with the effective electron discharge and higher substrate degradation.