• KSBB Journal
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• v.16 no.3
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• pp.225-232
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• 2001

The hydrophobicity of the microbial cell surface is responsible for the various interactions between microorganisms and different surface, and results in the flocculation of microbial cells, their adhesion to liquid or solid materials, and the floatation of microorganisms at the air-water interface. Accordingly, cell surface hydrophobicity is important not only in medicine but in other areas of biotechnology. This article reviews the role of cell surface hydrophobicity and its applications.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.6
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• pp.883-888
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• 2012

Anode electrode is one of the most important factors in microbial fuel cell (MFC). This study was conducted to investigate the effects of mediator as methylene blue (MB) and electrode surface area on the power density of MFC with sponge and carbon nano tube (CNT) electrode (SC). The SC electrode with MB (MC) showed the maximum power density increased from 74.0 $mW/m^2$ to 143.1 $mW/m^2$. The grid shaped sponge and CNT (GSC) electrode showed the maximum power density of 209.2 $mW/m^2$ due to the increase of surface area from 88.0 to 152.0 $cm^2$. The GSC electrode with MB (GMC) revealed the maximum power density of 384.9 $mW/m^2$ which was 5.2 times higher than that obtained from the MFC with SC. Therefore MB and increase of surface area led to enhance the performance of microbial fuel cell such as power density.

• Journal of Microbiology and Biotechnology
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• v.17 no.1
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• pp.110-115
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• 2007

Electrochemically active bacteria were successfully enriched in an electrochemical cell using a positively poised working electrode. The positively poised working electrode (+0.7 V vs. Ag/AgCl) was used as an electron acceptor for enrichment and growth of electrochemically active bacteria. When activated sludge and synthetic wastewater were fed to the electrochemical cell, a gradual increase in amperometric current was observed. After a period of time in which the amperometric current was stabilized (generally 8 days), linear correlations between the amperometric signals from the electrochemical cell and added BOD (biochemical oxygen demand) concentrations were established. Cyclic voltammetry of the enriched electrode also showed prominent electrochemical activity. When the enriched electrodes were examined with electron microscopy and confocal scanning laser microscopy, a biofilm on the enriched electrode surface and bacterium-like particles were observed. These experimental results indicate that the electrochemical system in this study is a useful tool for the enrichment of an electrochemically active bacterial consortium and could be used as a novel microbial biosensor.

• Microbiology and Biotechnology Letters
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• v.24 no.6
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• pp.733-737
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• 1996

The formation of microbial films(biofilm) by a non-sulfur phototrophic bacteria, Rhodopseudomonas capsulata, on inorganic media was studied. Porous ceramic beads(PCB) were superior to other immobilizing media for the biofilm formation in a packed-bed reactor. It was found that the formation of microbial films favored a lower hydraulic retention time, showing a higher ratio of cells attatched to the media to those suspended in the solution. The cell concentration in the biofilm reactor was as high as 11,400mg/l, which is 8-folds of the cell concentration in an ordinary suspended treatment. It was observed that the formation of micribial film by R. capsulata followed a general serial process of cell attachment, microcolony formation, and biofilm formation. The microbial films thus formed was very stable even for an extremely high volumetric BOD loading rate of 15gBOD/l day. The scanning electron micrographs of the microbial films showed that the cells were attached to both the surface and pores of the media.

• Proceedings of the Microbiological Society of Korea Conference
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• 2003.05a
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• pp.132-133
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• 2003

• Journal of Korean Society of Environmental Engineers
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• v.32 no.1
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• pp.87-96
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• 2010

The electrode material is one of the factors affecting the power production of microbial fuel cell. In this study, effects of carbon electrode material, thickness and configuration on the power density, biofilm formation and microbial community diversity of microbial fuel cell were investigated. To optimize the anode-cathode electrode assembly, seven lab-scale reactors which had various carbon electrode constructions were operated in continuous mode. Under the steady state condition, the electrode combination of graphite felt (6 mm) with hole showed the highest cell voltage of 238 mV and the coulombic efficiency of 37%. As a result of SEM analysis, the bacteria growing on surface of knitted type of carbon cloth and graphite felt electrode ncreased significantly. The change of dominant species between seeding sludge and biofilm on the surface of anode electrode, microbial analysis with PCR-DGGE showed that the dominant species of seeding sludge are quite different from those of biofilm on the surface of each anode electrode. Especially Geobacter sp., a well known electrochemical bacteria, was found as the dominant species of the electrode combination with graphite felt.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.4
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• pp.591-596
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• 2011

Surface floating air cathode microbial fuel cell (MFC) having horizontal flow was developed for the application of MFC technology. RVC (Reticulated vitreous carbon) coated with anyline was used as anode electrode and carbon cloth coated with Pt (5.0 g Pt/$m^2$, GDE LT250EW, E-TEK) was used as cathode electrode. As results of continuous operation with changing the flow rate from 4.3 mL/min to 9.5 mL/min, maximum power density of 4.5 W/$m^3$ was acquired at 5.4 mL/min, which was at 0.35 m/hr of flow velocity under anode electrode. When the ratio of cathode surface area to anode surface area($A_c/A_a$) was changed to 1.0, 0.5, and 0.25, the maximum power density of 2.7 W/$m^3$ was shown at the ratio of 1.0. As the ratio decreased from 1.0 to 0.25, the power density also decreased, which is caused by increasing the internal resistance resulted from reducing the surface area to contact with oxygen. Actually, internal resistances of the ratio of 1.0, 0.5, and 0.25 were 63.75${\Omega}$, 142.18${\Omega}$, and 206.12${\Omega}$, respectively.

• Journal of Electrochemical Science and Technology
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• v.12 no.3
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• pp.297-301
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• 2021

Microbial fuel cells (MFCs) convert chemical energy to electrical energy via electrochemically active microorganisms. The interactions between microbes and the surface of a carbon electrode play a vital role in capturing the respiratory electrons from bacteria. Therefore, improvements in the electrochemical and physicochemical properties of carbon materials are essential for increasing performance. In this study, a microwave and sulfuric acid treatment was used to modify the surface structure of graphite granules. The prepared expandable graphite granules (EGG) exhibited a 1.5 times higher power density than the unmodified graphite granules (1400 vs. 900 mW/m³). Scanning electron microscopy and Fourier transform infrared spectroscopy revealed improved physical and chemical characteristics of the EGG surface. These results suggest that physical and chemical surface modification using sulfuric acid and microwave heating improves the performance of electrode-based bioprocesses, such as MFCs.

• Applied Chemistry for Engineering
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• v.20 no.2
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• pp.213-217
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• 2009

Microbial fuel cells (MFCs) have been known as a new alternative energy conversion technology for treating wastewater and producing electricity simultaneously. A MFC converts the chemical energy of the organic compounds to electrical energy through microbial catalysis at the anode under anaerobic conditions. To examine the performance of MFC, in this work, the characteristics of the efficiency of wastewater treatment and generation of electricity was evaluated for sewage. When acetate as a carbon source was added into the sewage, the removal efficiency of COD was increased from 75.7% to 88.2% and the voltage was increased significantly from 0.22 V to 0.4 V. The influence of distance between anode and cathode was examined and the effect of the surface area of anode was investigated under the various external resistances. It was found that the maximum power density was $610mW/m^2$ and power generation was effective when the distance between the electrodes was shorter and the surface area of the anode was smaller.

• Journal of Microbiology and Biotechnology
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• v.19 no.9
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• pp.1019-1027
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• 2009

A noncompartmented microbial fuel cell (NCMFC) composed of a Mn(IV)-carbon plate and a Fe(III)-carbon plate was used for electricity generation from organic wastewater without consumption of external energy. The Fe(III)-carbon plate, coated with a porous ceramic membrane and a semipermeable cellulose acetate film, was used as a cathode, which substituted for the catholyte and cathode. The Mn(IV)-carbon plate was used as an anode without a membrane or film coating. A solar cell connected to the NCMFC activated electricity generation and bacterial consumption of organic matter contained in the wastewater. More than 99% of the organic matter was biochemically oxidized during wastewater flow through the four NCMFC units. A predominant bacterium isolated from the anode surface in both the conventional and the solar cell-linked NCMFC was found to be more than 99% similar to a Mn(II)-oxidizing bacterium and Burkeholderia sp., based on 16S rDNA sequence analysis. The isolate reacted electrochemically with the Mn(IV)-modified anode and produced electricity in the NCMFC. After 90 days of incubation, a bacterial species that was enriched on the Mn(IV)-modified anode surface in all of the NCMFC units was found to be very similar to the initially isolated predominant species by comparing 16S rDNA sequences.