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.

Young Ho Ahn

Advanced Materials Research • 2013

This paper provides feasibility estimation for actual domestic wastewater treatment under assumptions of a flow of 10,000 m3/d (about 40,000 capita), when air cathode MFCs configurations were adopted. Temperature-phased (mesophilic-ambient) process configurations in which can achieve either better effluent quality (i.e. maximizing treatment) or high energy recoveries is schematized. The performance used in the mass balance analysis of the treatment process conducted here compared with typical values in conventional biological wastewater treatment. Various advantages of using MFCs for wastewater treatment, including energy saving, less sludge production (and perhaps the lack of a need for a secondary clarifier), and no need for sludge handling, etc., were also addressed.

D. J. Juang

2012 IEEE International Conference on Power System Technology (POWERCON) • 2012

B Erable, E Blanchet, L. Etcheverry et al.

ECS Meeting Abstracts • 2014

The removal of the total organic load (COD) from urban wastewater was studied in different bio-electrochemical systems (BES): microbial electrolysis, microbial fuel cell (MFC), and microbial electrochemical snorkel (MES). Here is presented the concept of MES [1], a simplified design of a “short-circuited” MFC. The MES cannot provide current but it is optimized for wastewater treatment. Technically, the MES concept can simply consist of a single piece of conductive material on which there are (i) one end colonised by an electro-active biofilm acting as a microbial anode (anaerobic zone), and (ii) one end covered with oxygen (bio- or not) electro-catalyst that ensures electron removal to the final electron acceptor and allows bacteria “snorkelling” to oxygen. Unlike MFCs, a MES does not divert energy to produce electricity but it ensures maximum efficiency for the oxidation of organic matter. COD removal comparison with the different BES was made starting from optimized graphite based microbial anodes already working at steady state rate of oxidation. Optimization of microbial anodes consisted of immersing a microbial anode already colonized with electoactive microorganisms together with a second polarized clean electrode resulting in the formation of an electroactive biofilm on the clean electrode that became more effective than the initial one. This strategy multiplied the current provided by the second electrode by a factor ranging from 2 to 20 in respect to the initial one. Comparative analysis of microbial diversity on electrodes was performed by pyrosequencing technology. Then, the comparative study using microbial anodes in different BES for the treatment of urban wastewater validated the MES concept since the MES process ensured about 75% of wastewater COD removal in less than 24 hours as well as a “short-circuited” MFC. In conclusion, the MES technology, which aims at maximizing the reaction rates by elimination of current generation, provided degradation performance far higher than the MFCs that operated at optimum power. This demonstration opens a new route for the design of extremely simple electro-microbial devices for wastewater treatment. [1] B. Erable et al., 2011. Biofouling 27(3):319-326. doi: 10.1080/08927014.2011.564615.

Udayarka Karra, Elizabeth Troop, Michael Curtis et al.

Proceedings of the Water Environment Federation • 2012

Dan Gong, Gang Qin

Desalination and Water Treatment • 2012

S. Venkata Mohan, G. Mohanakrishna, S. Srikanth et al.

Fuel • 2008

Yevgenia Ulyanova, Sameer Singhal

ECS Meeting Abstracts • 2014

According to a number of reports about 90% of “used” water or wastewater remains untreated, and is pumped back into the environment, causing global pollution. Proper treatment is needed prior to releasing this water back into the ecosystem or re-purposing it for alternate uses. To meet the above-described need, a microbial fuel cell (MFC) has been developed, that can simultaneously generate energy from wastewater while also removing contaminants and allowing for its reuse, thereby greatly offsetting the net energy costs of water treatment. A MFC is a device that directly converts chemical energy, derived through microbial metabolism, to electrical energy. Specifically for this system the organic contaminants are processed at the anode, while heavy metal (ex. hexavalent chromium) contamination is removed at the cathode. This configuration of the MFC presents the novelty in the system’s design as compared to existing MFC technologies. The method for bioremediation of organic and heavy metal contaminants in wastewater is different. Organic contaminants are oxidized during wastewater treatment to carbon dioxide, whereas heavy metals are typically reduced to a safe metallic form. Therefore, separate types of bacteria are employed for anode and cathode fabrication. The bioanode bacteria, Shewanella oneidensis strain MR-1 [ 1 ], has been widely studied[ 2 ] for the use in MFC. Bacterial attachment is facilitated by entrapment in biopolymers with carbon nanomaterials (including high surface area porous carbons and graphene) followed by incubation to allow for biofilm growth. Previous work has shown that these composite electrodes form very stable bioelectrodes that can be used for months without degradation[ 3 ]. Spectroscopic activity assays (Figure 1) along with amperometric activity assays for oxidation of organic substrates are employed to study the effects of bacterial immobilization and catalytic performance at modified bioelectrodes.

Fei Zhang, Zhen He

Process Biochemistry • 2012

Feng Zhu, Wancheng Wang, Xiaoyan Zhang et al.

Bioresource Technology • 2011

A novel membrane-less microbial fuel cell (MFC) with down-flow feeding was constructed to generate electricity. Wastewater was fed directly onto the cathode which was horizontally installed in the upper part of the MFC. Oxygen could be utilized readily from the air. The concentration of dissolved oxygen in the influent wastewater had little effect on the power generation. A saturation-type relationship was observed between the initial COD and the power generation. The influent flow rate could affect greatly the power density. Fed by the synthetic glucose wastewater with a COD value of 3500 mg/L at a flow rate of 4.0 mL/min, the developed MFC could produce a maximum power density of 37.4 mW/m(2). Its applicability was further evaluated by the treatment of brewery wastewater. The system could be scaled up readily due to its simple configuration, easy operation and relatively high power density.

Bin Hou, Jian Sun, Yong-you Hu

Bioresource Technology • 2011

Different microfiltration membrane (MFM), proton exchange membrane (PEM) and ultrafiltration membranes (UFMs) with different molecular cutoff weights of 1K (UFM-1K), 5K (UFM-5K) and 10K (UFM-10K) were incorporated into air-cathode single-chamber microbial fuel cells (MFCs) which were explored for simultaneous azo dye decolorization and electricity generation to investigate the effect of membrane on the performance of the MFC. Batch test results showed that the MFC with an UFM-1K produced the highest power density of 324 mW/m(2) coupled with an enhanced coulombic efficiency compared to MFM. The MFC with UMF-10K achieved the fastest decolorization rate (4.77 mg/L h), followed by MFM (3.61 mg/L h), UFM-5K (2.38 mg/L h), UFM-1K (2.02 mg/Lh) and PEM (1.72 mg/Lh). These results demonstrated the possibility of using various membranes in the system described here, and showed that UFM-1K was the best one based on the consideration of both cost and performance.

Seo Ha Na

Journal of Microbiology and Biotechnology • 2009

Qing Wen, Fanying Kong, Hongtao Zheng et al.

Chemical Engineering Journal • 2011

Chiu Yu Cheng, Fang Yu Liang, Ying Chien Chung

Advanced Materials Research • 2013

Microbial fuel cell (MFC) provides a new opportunity for the sustainable production of energy from the textile wastewater. However, limited studies revealed the high electricity generation using a single-chambered MFC in treating crystal violet (CV) containing wastewater. This study isolated an exoelectrogen Aeromonas hydrophila YC 57, inoculated to a single-chambered MFC and intended to achieve a high power output. The results showed that the removal efficiency of CV and coulombic efficiency of MFC by A. hydrophila YC 57 were achieved at 82.5±0.7% and 57.2±0.5% at initial CV concentration of 100 mg/L, respectively. The maximum power generation of MFC was 240±5.6 mW/m2. Results of cyclic voltammogram hinted the intermediate products of CV dye played roles of mediators. Toxicity studies revealed that metabolites of CV produced by A. hydrophila YC 57 were nontoxic. To our knowledge, this is the first time to demonstrate the electricity characteristics of a single-chambered MFC inoculated A. hydrophila YC 57.

Xiaoying Kong, Yongming Sun, Ying Li et al.

2011 International Conference on Remote Sensing, Environment and Transportation Engineering • 2011

Two different microbial fuel cell (MFC) configurations were investigated for electricity production from ethanol and methanol: a two-chambered, aqueous-cathode MFC; and a single-chamber direct-air cathode MFC. Electricity was generated in the two-chamber system at a maximum power density typical of this system (40+/-2 mW/m2) and a Coulombic efficiency (CE) ranging from 42% to 61% using ethanol. When bacteria were transferred into a single-chamber MFC known to produce higher power densities with different substrates, the maximum power density increased to 488+/-12 mW/m2 (CE = 10%) with ethanol. The voltage generated exhibited saturation kinetics as a function of ethanol concentration in the two-chambered MFC, with a half-saturation constant (Ks) of 4.86 mM. Methanol was also examined as a possible substrate, but it did not result in appreciable electricity generation. Analysis of the anode biofilm and suspension from a two-chamber MFC with ethanol using 16S rDNA-based techniques indicated that bacteria with sequences similar to Proteobacterium Core-1 (33.3% of clone library sequences), Azoarcus sp. (17.4%), and Desulfuromonas sp. M76 (15.9%) were significant members of the anode chamber community. These results indicate that ethanol can be used for sustained electricity generation at room temperature using bacteria on the anode in a MFC.

Satish S. Rikame, Alka A. Mungray, Arvind K. Mungray

International Biodeterioration & Biodegradation • 2012

Zhuwei DU, Qinghai LI, Meng TONG et al.

Chinese Journal of Chemical Engineering • 2008

Microbial fuel cells have gained popularity in recent years due to its promise in converting organic wastewater into renewable electrical energy. In this study, a membrane-less MFC with a biocathode was developed to evaluate its performance in electricity generation while simultaneously treating wastewater. The MFC fed with a continuous flow of 2g/day acetate produced a power density of 30 mW/m(2) and current density of 245 mA/m(2). A substrate degradation efficiency (SDE) of 75.9% was achieved with 48.7% attributed to the anaerobic process and 27.2% to the aerobic process. Sequencing analysis of the microbial consortia using 16S rDNA pryosequencing showed the predominance of Bacteroidia in the anode after one month of operation, while the microbial community in the cathode chamber was dominated by Gamma-proteobacteria and Beta-proteobacteria. Coulombic efficiencies varied from 19.8% to 58.1% using different acetate concentrations, indicating power density can be further improved through the accumulation of electron-transferring bacteria.

Z Yavari, H Izanloo, K Naddafi et al.

International Journal of Renewable Energy Development • 2013

Renewable energy will have an important role as a resource of energy in the future. Microbial fuel cell (MFC) is a promising method to obtain electricity from organic matter and wastewater treatment simultaneously. In a pilot study, use of microbial fuel cell for wastewater treatment and electricity generation investigated. The bacteria of ruminant used as inoculums. Synthetic wastewater used at different organic loading rate. Hydraulic retention time was an effective factor in removal of soluble COD and more than 49% removed. Optimized HRT to achieve the maximum removal efficiency and sustainable operation could be regarded 1.5 and 2.5 hours. Columbic efficiency (CE) affected by organic loading rate (OLR) and by increasing OLR, CE reduced from 71% to 8%. Maximum voltage was 700mV. Since the microbial fuel cell reactor considered as an anaerobic process, it may be an appropriate alternative for wastewater treatment

M.H. Cho, S. Kalathil, S.-H. Shim et al.

Journal of Biotechnology • 2010

Jiexun Huang, Baolin Sun, Xiaobo Zhang

Applied Microbiology and Biotechnology • 2009

Increasing the ionic strength of the electrolyte in a microbial fuel cell (MFC) can remarkably increase power output due to the reduction of internal resistance. However, only a few bacterial strains are capable of producing electricity at a very high ionic strength. In this report, we demonstrate a newly isolated strain EP1, belonging to Shewanella marisflavi based on polyphasic analysis, which could reduce Fe(III) and generate power at a high ionic strength of up to 1,488 mM (8% NaCl) using lactate as the electron donor. Using this bacterium, a measured maximum power density of 3.6 mW/m(2) was achieved at an ionic strength of 291 mM. The maximum power density was increased by 167% to 9.6 mW/m(2) when ionic strength was increased to 1,146 mM. However, further increasing the ionic strength to 1,488 mM resulted in a decrease in power density to 5.2 mW/m(2). Quantification of the internal resistance distribution revealed that electrolyte resistance was greatly reduced from 1,178 to 50 Omega when ionic strength increased from 291 to 1,488 mM. These results indicate that isolation of specific bacterial strains can effectively improve power generation in some MFC applications.

Jin-Na Zhang, Qing-Liang Zhao, Peter Aelterman et al.

Biotechnology Letters • 2008

A microbial fuel cell using aerobic microorganisms as the cathodic catalysts is described. By using anaerobic sludge in the anode and aerobic sludge in the cathode as inocula, the microbial fuel cell could be started up after a short lag time of 9 days, generating a stable voltage of 0.324 V (R (ex) = 500 Omega). At an aeration rate of 300 ml min(-1) in the cathode, a maximum volumetric power density of up to 24.7 W m(-3) (117.2 A m(-3)) was reached. This research demonstrates an economic system for recovering electrical energy from organic compounds.

Ergin Taskan, Halil Hasar, Bestamin Ozkaya

Applied Mechanics and Materials • 2013

Microbial fuel cell (MFC) provides the generation of electricity as bacteria on anode electrode oxidize organic content present in wastewater. This study presents simultaneously the electricity generation from two different synthetic wastewater mixtures using a new electrode in both anode and cathode compartments. Results showed that power output increased excessively in the case of Ti-TiO2 electrode. MFC reactors were mainly dominated by Geobacter, Shewanella, Pseudomonas and Clostridium species. The molecular results also demonstrated that Ti-TiO2 electrode is biocompatibility and able to be used in MFC because these species are electricity producing bacteria.

Booki Min, Bruce E. Logan

Environmental Science & Technology • 2004

A microbial fuel cell (MFC) is a device that converts organic matter to electricity using microorganisms as the biocatalyst. Most MFCs contain two electrodes separated into one or two chambers that are operated as a completely mixed reactor. In this study, a flat plate MFC (FPMFC) was designed to operate as a plug flow reactor (no mixing) using a combined electrode/proton exchange membrane (PEM) system. The reactor consisted of a single channel formed between two nonconductive plates that were separated into two halves by the electrode/PEM assembly. Each electrode was placed on an opposite side of the PEM, with the anode facing the chamber containing the liquid phase and the cathode facing a chamber containing only air. Electricity generation using the FPMFC was examined by continuously feeding a solution containing wastewater, or a specific substrate, into the anode chamber. The system was initially acclimated for 1 month using domestic wastewater orwastewater enriched with a specific substrate such as acetate. Average power density using only domestic wastewater was 72+/-1 mW/m2 at a liquid flow rate of 0.39 mL/min [42% COD (chemical oxygen demand) removal, 1.1 h HRT (hydraulic retention time)]. At a longer HRT = 4.0 h, there was 79% COD removal and an average power density of 43+/-1 mW/m2. Power output was found to be a function of wastewater strength according to a Monod-type relationship, with a half-saturation constant of Ks = 461 or 719 mg COD/L. Power generation was sustained at high rates with several organic substrates (all at approximately 1000 mg COD/L), including glucose (212+/-2 mW/ m2), acetate (286+/-3 mW/m2), butyrate (220+/-1 mW/ m2), dextran (150+/-1 mW/m2), and starch (242+/-3 mW/ m2). These results demonstrate the versatility of power generation in a MFC with a variety of organic substrates and show that power can be generated at a high rate in a continuous flow reactor system.

Elangovan Mahendiravarman, Dharmalingam Sangeetha

International Journal of Hydrogen Energy • 2013

Farzaneh Rezaei, Tom L. Richard, Bruce E. Logan

Biotechnology and Bioengineering • 2008

AbstractElectricity can be directly generated by bacteria in microbial fuel cells (MFCs) from a variety of biodegradable substrates, including cellulose. Particulate materials have not been extensively examined for power generation in MFCs, but in general power densities are lower than those produced with soluble substrates under similar conditions likely as a result of slow hydrolysis rates of the particles. Cellulases are used to achieve rapid conversion of cellulose to sugar for ethanol production, but these enzymes have not been previously tested for their effectiveness in MFCs. It was not known if cellulases would remain active in an MFC in the presence of exoelectrogenic bacteria or if enzymes might hinder power production by adversely affecting the bacteria. Electricity generation from cellulose was therefore examined in two‐chamber MFCs in the presence and absence of cellulases. The maximum power density with enzymes and cellulose was 100 ± 7 mW/m2 (0.6 ± 0.04 W/m3), compared to only 12 ± 0.6 mW/m2 (0.06 ± 0.003 W/m3) in the absence of the enzymes. This power density was comparable to that achieved in the same system using glucose (102 ± 7 mW/m2, 0.56 ± 0.038 W/m3) suggesting that the enzyme successfully hydrolyzed cellulose and did not otherwise inhibit electricity production by the bacteria. The addition of the enzyme doubled the Coulombic efficiency (CE) to CE = 51% and increased COD removal to 73%, likely as a result of rapid hydrolysis of cellulose in the reactor and biodegradation of the enzyme. These results demonstrate that cellulases do not adversely affect exoelectrogenic bacteria that produce power in an MFC, and that the use of these enzymes can increase power densities and reactor performance. Biotechnol. Bioeng. © 2008 Wiley Periodicals, Inc.

H. Liu, T.J. Hu, G.M. Zeng et al.

International Biodeterioration & Biodegradation • 2012

Yujie Feng, Qiao Yang, Xin Wang et al.

Bioresource Technology • 2010

Biodiesel production through transesterification of lipids generates large quantity of biodiesel waste (BW) containing mainly glycerin. BW can be treated in various ways including distillation to produce glycerin, use as substrate for fermentative propanediol production and discharge as wastes. This study examined microbial fuel cells (MFCs) to treat BW with simultaneous electricity generation. The maximum power density using BW was 487 ± 28 mW/m(2) cathode (1.5A/m(2) cathode) with 50mM phosphate buffer solution (PBS) as the electrolyte, which was comparable with 533 ± 14 mW/m(2) cathode obtained from MFCs fed with glycerin medium (COD 1400 mg/L). The power density increased from 778 ± 67 mW/m(2) cathode using carbon cloth to 1310 ± 15 mW/m(2) cathode using carbon brush as anode in 200 mM PBS electrolyte. The power density was further increased to 2110 ± 68 mW/m(2) cathode using the heat-treated carbon brush anode. Coulombic efficiencies (CEs) increased from 8.8 ± 0.6% with carbon cloth anode to 10.4 ± 0.9% and 18.7 ± 0.9% with carbon brush anode and heat-treated carbon brush anode, respectively.

Ngoc Trung Trinh, Jong Hyeok Park, Byung-Woo Kim

Korean Journal of Chemical Engineering • 2009

Qiao Yang, Xin Wang, Yujie Feng et al.

Fuel • 2012

Krishna P. Katuri, K. Scott

Biotechnology and Bioengineering • 2010

AbstractThe performance of a prototype up‐flow single‐chambered microbial fuel cell (MFC) for electrical power generation using brewery wastewater as fuel is reported. The designed reactor consisted of three zones, namely a lower anaerobic digestion zone, a central MFC zone, and an upper effluent clarifier zone. Tests were conducted in batch mode using a beer wastewater as the fuel/electron donor (COD concentration: 430 mg/L) and mixed consortia (both sewage microflora and anaerobic sludge) as a source of electrogenic bacteria. A stable current density of ∼2,270 mA/m2 was generated under continuous polarization with a constant external resistance (0.01 kΩ) and cell polarization gave a peak power density of 330 mW/m2 at a current density of 1,680 mA/m2. Electrochemical impedance analysis showed that the overall internal resistance of the reactor was quite low, that is, 8.0 Ω. Cyclic voltammetric analysis of the anodic biofilm at low scan rate revealed quite complex processes at the anode, with three redox peaks, at potentials of 116, 214, and 319 mV (vs. NHE). Biotechnol. Bioeng. 2010;107: 52–58. © 2010 Wiley Periodicals, Inc.