Jang, Jae Kyung
(Department of Earth Sciences, University of Southern California)
,
Kan, Jinjun
(Department of Earth Sciences, University of Southern California)
,
Bretschger, Orianna
(Mork Family Department of Chemical Engineering and Materials Science, University of Southern California)
,
Gorby, Yuri A.
(The J. Craig Venter Insitute)
,
Hsu, Lewis
(Department of Civil and Environmental Engineering, University of Southern California)
,
Kim, Byung Hong
(Department of Earth Sciences, University of Southern California)
,
Nealson, Kenneth H.
(Department of Earth Sciences, University of Southern California)
The cathode reaction is one of the most seriously limiting factors in a microbial fuel cell (MFC). The critical dissolved oxygen (DO) concentration of a platinum-loaded graphite electrode was reported as 2.2 mg/l, about 10-fold higher than an aerobic bacterium. A series of MFCs were run with the cat...
The cathode reaction is one of the most seriously limiting factors in a microbial fuel cell (MFC). The critical dissolved oxygen (DO) concentration of a platinum-loaded graphite electrode was reported as 2.2 mg/l, about 10-fold higher than an aerobic bacterium. A series of MFCs were run with the cathode compartment inoculated with activated sludge (biotic) or not (abiotic) on platinum-loaded or bare graphite electrodes. At the beginning of the operation, the current values from MFCs with a biocathode and abiotic cathode were $2.3{\pm}0.1$ and $2.6{\pm}0.2mA$, respectively, at the air-saturated water supply in the cathode. The current from MFCs with an abiotic cathode did not change, but that of MFCs with a biotic cathode increased to 3.0 mA after 8 weeks. The coulomb efficiency was 59.6% in the MFCs with a biotic cathode, much higher than the value of 15.6% of the abiotic cathode. When the DO supply was reduced, the current from MFCs with an abiotic cathode decreased more sharply than in those with a biotic cathode. When the respiratory inhibitor azide was added to the catholyte, the current decreased in MFCs with a biotic cathode but did not change in MFCs with an abiotic cathode. The power density was higher in MFCs with a biotic cathode ($430W/m^3$ cathode compartment) than the abiotic cathode MFC ($257W/m^3$ cathode compartment). Electron microscopic observation revealed nanowire structures in biofilms that developed on both the anode and on the biocathode. These results show that an electron-consuming bacterial consortium can be used as a cathode catalyst to improve the cathode reaction.
The cathode reaction is one of the most seriously limiting factors in a microbial fuel cell (MFC). The critical dissolved oxygen (DO) concentration of a platinum-loaded graphite electrode was reported as 2.2 mg/l, about 10-fold higher than an aerobic bacterium. A series of MFCs were run with the cathode compartment inoculated with activated sludge (biotic) or not (abiotic) on platinum-loaded or bare graphite electrodes. At the beginning of the operation, the current values from MFCs with a biocathode and abiotic cathode were $2.3{\pm}0.1$ and $2.6{\pm}0.2mA$, respectively, at the air-saturated water supply in the cathode. The current from MFCs with an abiotic cathode did not change, but that of MFCs with a biotic cathode increased to 3.0 mA after 8 weeks. The coulomb efficiency was 59.6% in the MFCs with a biotic cathode, much higher than the value of 15.6% of the abiotic cathode. When the DO supply was reduced, the current from MFCs with an abiotic cathode decreased more sharply than in those with a biotic cathode. When the respiratory inhibitor azide was added to the catholyte, the current decreased in MFCs with a biotic cathode but did not change in MFCs with an abiotic cathode. The power density was higher in MFCs with a biotic cathode ($430W/m^3$ cathode compartment) than the abiotic cathode MFC ($257W/m^3$ cathode compartment). Electron microscopic observation revealed nanowire structures in biofilms that developed on both the anode and on the biocathode. These results show that an electron-consuming bacterial consortium can be used as a cathode catalyst to improve the cathode reaction.
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문제 정의
This study aimed to ascertain whether the current generation was associated with the action of bacteria at the cathode through the use of a respiratory inhibitor. When the current was stably generated at around 3.
제안 방법
In this study, an MFC with a biocathode was studied in order to determine the possibility of using bacteria as a catalyst instead of Pt or other abiotic materials. A biotic cathode using aerobic bacteria having low potential can improve current generation because the critical oxygen concentration of aerobic bacteria is known to be 0.
These studies were attempted to determine the effect of the DO concentration on current generation in MFCs with a biotic or abiotic cathode. For these studies, fuel with 100 mg/l as COD was fed into the anode compartment at a flow rate of 0.
In order to gain further insight into the role of the microorganisms associated with the cathode reaction, the microbial community on the anode and cathode was examined using a denaturing gradient gel electrophoesis (DGGE) and 16S rRNA gene clone library approach. The sequences used were from intense bands in the DGGE fingerprint.
대상 데이터
, USA) was used as the electrodes with platinum wire connecting them through a resistor and a multimeter. Two sheets of graphite felt were used in the anode and one in the cathode. The anode compartment was kept anoxic by use of a nitrogen gas bag.
These procedures were repeated three times. The DGGE bands were sequenced using the primer 907R. All sequences were compared with the GenBank database using BLAST, and the closest matched bacterial strains were obtained.
성능/효과
Nine of the 16 sequences were related to the Proteobacteria. A close look at these results shows that five were Betaproteobacteria, three were Deltaproteobacteria, and one was Alphaproteobacteria. In addition to this, there were Actinobacteria, Bacteroidetes, and Firmicutes groups.
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