• Journal of Microbiology and Biotechnology
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• 제26권4호
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• pp.757-762
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• 2016

The group of Fe(III) oxide-reducing bacteria includes exoelectrogenic bacteria, and they possess similar properties of transferring electrons to extracellular insoluble-electron acceptors. The exoelectrogenic bacteria can use the anode in microbial fuel cells (MFCs) as the terminal electron acceptor in anaerobic acetate oxidation. In the present study, the anodic community was compared with the community using Fe(III) oxide (ferrihydrite) as the electron acceptor coupled with acetate oxidation. To precisely analyze the structures, the community was established by enrichment cultures using the same inoculum used for the MFCs. High-throughput sequencing of the 16S rRNA gene revealed considerable differences between the structure of the anodic communities and that of the Fe(III) oxide-reducing community. Geobacter species were predominantly detected (>46%) in the anodic communities. In contrast, Pseudomonas (70%) and Desulfosporosinus (16%) were predominant in the Fe(III) oxide-reducing community. These results demonstrated that Geobacter species are the most specialized among Fe(III)-reducing bacteria for electron transfer to the anode in MFCs. In addition, the present study indicates the presence of a novel lineage of bacteria in the genus Pseudomonas that highly prefers ferrihydrite as the terminal electron acceptor in acetate oxidation.

• 멤브레인
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• 제30권4호
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• pp.213-227
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• 2020

재생 불가능한 에너지 자원이 수년에 걸쳐 고갈됨에 따라, 재생 에너지 생산을 위한 보다 효과적인 방법에 대한 연구가 증가되었다. 연로전지 개발의 한 분야인 미생물 연료전지(MFC)는 이중 성능의 잠재력 덕분에 발전하였다. MFC는 박테리아와 같은 전극 감소 생물에서 전력을 모아서 전기 에너지를 생산한다. MFC는 폐수를 연료로 사용하여 에너지를 생산하고 폐수를 정화한다. 양성자 교환막(PEM)은 양극과 음극 챔버의 분리막으로, 양성자만 효과적으로 통과할 수 있게 하는 중요한 역할을 한다. Nafion은 MFC에 상업적으로 사용되는 PEM이지만 비용, 생산 시간, 양성자 전도성 차원에서 보완할 점들이 많다. 본 리뷰 논문에는 Nafion을 대체할 수 있는 새로 개발된 PEM 몇 가지를 논의하였다. 또한, PEM, 혼합 PEM 및 복합 PEM에 기반한 MFC를 요약하고자 한다.

• Environmental Engineering Research
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• 제18권3호
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• pp.145-150
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• 2013

Optimal preparation guidelines of a cathode catalyst layer by non-precious metal catalysts were evaluated based on electrochemical performance in single-chamber microbial fuel cells (MFCs). Experiments for catalyst loading rate revealed that iron(II) phthalocyanine (FePc) can be a promising alternative, comparable to platinum (Pt) and cobalt tetramethoxyphenylporphyrin (CoTMPP), including effects of substrate concentration. Results showed that using an optimal FePc loading of $1mg/cm^2$ was equivalent to a Pt loading of $0.35mg/cm^2$ on the basis of maximum power density. Given higher loading rates or substrate concentrations, FePc proved to be a better alternative for Pt than CoTMPP. Under the optimal loading rate, it was further revealed that 40 wt% of FePc to carbon support allowed for the best power generation. These results suggest that proper control of the non-precious metal catalyst layer and substrate concentration are highly interrelated, and reveal how those combinations promote the economic power generation of single-chamber MFCs.

• KSBB Journal
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• 제29권4호
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• pp.225-231
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• 2014

A microbial fuel cell (MFC) and bioelectrochemical systems are novel bioprocesses which employ exoelectrogenic biofilm on electrode as a biocatalyst for electricity generation and various useful chemical production. Previous reports show that electrogenic biofilms of MFCs are time varying systems and dynamically interactive with the electrically conductive media (carbon paper as terminal electron acceptor). It has been reported that maximum power point tracking (MPPT) method can automatically control load by algorithm so that increase power generation and columbic efficiency. In this study, we developed logic based control strategy for external load resistance by using $LabVIEW^{TM}$ which increases the power production with using flat-plate MFCs and MPPT circuit board. The flat-plate MFCs inoculated with anaerobic digester sludge were stabilized with fixed external resistance from $1000{\Omega}$ to $100{\Omega}$. Automatic load control with MPPT started load from $52{\Omega}$ during 120 hours of operation. MPPT control strategy increased approximately 2.7 times of power production and power density (1.95 mW and $13.02mW/m^3$) compared to the initial values before application of MPPT (0.72 mW and $4.79mW/m^3$).

• 한국물환경학회지
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• 제26권4호
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• pp.608-613
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• 2010

Electricity generation of microbial fuel cells (MFC) is greatly affected by the kind of feed substrates because substrates would change microbial community of electrochemically active bacteria (EAB) able to transfer electrons to electrode. The effect of different substrates on electricity generation and microbial community of MFC was investigated. Two-chamber MFCs fed with acetate (A-MFC), butyrate (B-MFC), propionate (P-MFC), glucose (G-MFC) and a mixture (M-MFC) of the 4 substrates (acetate : butyrate : propionate : glucose = 1 : 1 : 1 : 1 as $COD_{Cr}$ base) were operated under continuous mode. The maximum power density was found from the M-MFC ($190W/m^3$) which showed the lowest internal resistance ($89{\Omega}$). The maximum power densities of the pure substrates feed MFCs were in order of A-MFC ($25W/m^3$), P-MFC ($21W/m^3$), B-MFC ($20W/m^3$) and G-MFC ($9W/m^3$). In DGGE analysis, the microbial community structure in suspension was quite different from each others depending on feed substrates, while the community structure in the biofilm was relatively similar regardless of the substrates. This result suggests that the feed substrates would affect the microbial community of suspended growth bacteria than attached growth bacteria resulting in difference of electricity generation in MFCs.

• 한국수소및신에너지학회논문집
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• 제26권3호
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• pp.247-259
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• 2015

This study was performed to investigate the application of dark $H_2$ fermentation to two-stage bioprocesses for organic waste treatment and energy production. We reviewed information about the two-stage bioprocesses combining dark $H_2$ fermentation with $CH_4$ fermentation, photo $H_2$ fermentation, microbial fuel cells (MFCs), or microbial electrolysis cells (MECs) by using academic information databases and university libraries. Dark fermentative bacteria use organic waste as the sole source of electrons and energy, converting it into $H_2$. The reactions related to dark $H_2$ fermentation are rapid and do not require sunlight, making them useful for treating organic waste. However, the degradation is not complete and organic acids remain. Thus, dark $H_2$ fermentation should be combined with a post-treatment process, such as $CH_4$ fermentation, photo $H_2$ fermentation, MFCs, or MECs. So far, dark $H_2$ fermentation followed by $CH_4$ fermentation is a promising two-stage bioprocess among them. However, if the problems of manufacturing expenses, operational cost, scale-up, and practical applications will be solved, the two-stage bioprocesses combining dark $H_2$ fermentation with photo $H_2$ fermentation, MFCs, or MECs have also infinite potential in organic waste treatment and energy production. This paper demonstrated the feasibility of two-stage bioprocesses combining dark $H_2$ fermentation as a novel system for organic waste treatment and energy production.

• Membrane and Water Treatment
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• 제6권1호
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• pp.53-75
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• 2015

This paper provides an overview of the role of membranes in bioelectrochemical systems (BESs). Bioelectrochemical systems harvest clean energy from waste organic sources by employing indigenous exoelectrogenic bacteria. This energy is extracted in the form of bioelectricity or valuable biofuels such as ethanol, methane, hydrogen, and hydrogen peroxide. Various types of membranes were applied in these systems, the most common membrane being the cation exchange membrane. In this paper, we discuss three major bioelectrochemical technology research areas namely microbial fuel cells (MFCs), microbial electrolysis cells (MECs) and microbial desalination cells (MDCs). The operation principles of these BESs, role of membranes in these systems and various factors that affect their performance and economics are discussed in detail. Among the three technologies, the MFCs may be functional with or without membranes as separators while the MECs and MDCs require membrane separators. The preliminary economic analysis shows that the capital and operational costs for BESs will significantly decrease in the future due mainly to differences in membrane costs. Currently, MECs appear to be cost-competitive and energy-yielding technology followed by MFCs. Future research endeavors should focus on maximizing the process benefits while simultaneously minimizing the membrane costs related to fouling, maintenance and replacement.

• Environmental Engineering Research
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• 제24권3호
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• pp.443-448
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• 2019

The present study was conducted to compare the voltage generation in two-chamber microbial fuel cells (MFCs) with a biocathode where nitrate and oxygen are used as a terminal electron acceptors (TEA) and to investigate the nitrogen removal and the electrochemical characteristics depending on the separators of the MFCs for denitrification. The maximum power density in a biocathode MFC using an anion exchange membrane (AEM) was approximately 40% lower with the use of nitrate as a TEA than when using oxygen. The MFC for denitrification using an AEM allows acetate ($CH_3COO^-$) as a substrate and nitrate ($NO_3{^-}$) as a TEA to be transported to the opposite sides of the chamber through the AEM. Therefore, heterotrophic denitrification and electrochemical denitrification occurred simultaneously at the anode and the cathode, resulting in a higher COD and nitrate removal rate and a lower maximum power density. The MFC for the denitrification using a cation exchange membrane (CEM) does not allow the transport of acetate and nitrate. Therefore, as oxidation of organics and electrochemical denitrification occurred at the anode and at the cathode, respectively, the MFC using a CEM showed a higher coulomb efficiency, a lower COD and nitrate removal rate in comparison with the MFC using an AEM.

• Journal of Electrochemical Science and Technology
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• 제14권4호
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• pp.303-310
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• 2023

Microbial fuel cells (MFCs) are a bioelectrochemical system where electrochemically active bacteria convert organic waste into electricity. Poly(vinyl alcohol) (PVA) and chitosan (CS) are polymers that have been studied as potential alternative ion exchange membranes to Nafion for many electrochemical systems. This study examined the optimal mixing ratio of PVA and chitosan CS in a PVA:CS composite membrane for MFC applications. PVA:CS composite membranes with 1:1, 2:1, and 3:1 ratios were synthesized and tested. The water uptake and ion exchange capacity, Fourier transform infrared spectra, and scanning electron microscopy images were analyzed to determine the physicochemical properties of PVA:CS membranes. The prepared membranes were applied to the ion exchange membrane of the MFC system, and their effects on the electrochemical performance were evaluated. These results showed that the composite membrane with a 3:1 (PVA:CS) ratio showed comparable performance to the commercialized Nafion membrane and produced more electricity than the other synthesized membranes. The PVA:CS membrane implemented MFCs produced a maximum power density of 0.026 mW cm^-2 from organic waste with stable performance. Therefore, it can be applied to a cost-effective MFC system.

• Bulletin of the Korean Chemical Society
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• 제34권12호
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• pp.3649-3653
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• 2013

As anode fabrication with different materials has been proven to be a successful alternative for enhancing power generation in the microbial fuel cells, a new approach to improved performance of MFCs with the use of menadione/carbon powder composite-modified carbon cloth anode has been explored in this study. Menadione has formal potential to easily accept electrons from the outer membrane cytochromes of electroactive bacteria that can directly interact with the solid surface. Surface bound menadione was able to maintain an electrical wiring with the trans-membrane electron transfer pathways to facilitate extracellular electron transfer to the electrode. In a single chamber air cathode MFC inoculated with aerobic sludge, maximum power density of $1250{\pm}35mWm^{-2}$ was achieved, which was 25% higher than that of an unmodified anode. The observed high power density and improved coulomb efficiency of 61% were ascribed to the efficient electron shuttling via the immobilized menadione.