Biological Denitrification in Microbial Fuel Cells

Clauwaert, Peter; Rabaey, Korneel; Aelterman, Peter; Schamphelaire, Liesje De; Pham, The Hai; Boeckx, Pascal; Boon, Nico; Verstraete, Willy

doi:10.1021/es062580r

Cited by 756 publications

(408 citation statements)

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“…Potassium hexacyanoferrate (K 3 Fe(CN) 6 ) has been used in laboratory studies due to its ability to provide a constant cathodic potential . Nitrate can be reduced to N 2 in biocatalysed cathodes (Clauwaert et al, 2007), which enable removal of this nutrient aside from the anode-associated organic carbon removal. For energy generation, oxygen is the preferred electron acceptor due to its abundant availability and high redox potential (Zhao et al, 2006).…”

Section: Article In Pressmentioning

confidence: 99%

Sequential anode–cathode configuration improves cathodic oxygen reduction and effluent quality of microbial fuel cells

et al. 2008

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a b s t r a c tThe reduction of oxygen at the cathode and the diffusion of protons from the anode to the cathode are currently perceived as two major bottlenecks of microbial fuel cells (MFCs). To address these issues, we have designed an MFC configuration in which the effluent of an acetate-fed anode was used as a feed for an aerated, biocatalysed cathode. The development of a cathodic biofilm achieved a four-fold increase of the current output compared with the non-catalysed graphite cathode, while the pH variation in the cathode compartment was reduced due to the additional transfer of protons via the liquid stream.The sequential anode-cathode configuration also provided for chemical oxygen demand Electron balances at the cathode revealed that the main cathodic process was oxygen reduction to water with no significant Coulombic losses. The maximal power output during polarization was 110 W/m 3 cathode liquid volume. The process could be operated in a stable way during more than 9 months of continuous operation. Excessive organic loading to the cathode should be avoided as it can reduce the long-term performance through the growth of heterotrophic bacteria.

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Section: Article In Pressmentioning

confidence: 99%

Sequential anode–cathode configuration improves cathodic oxygen reduction and effluent quality of microbial fuel cells

et al. 2008

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“…When net electrical energy is obtained from a BES, the system is referred to as a microbial fuel cell (MFC). This technology includes anodic reactions where electron donors, such as organic compounds and sulfide, are oxidized, and cathodic reactions where electron acceptors, such as oxygen, nitrate, nitrite or perchlorate, are reduced (Clauwaert et al, 2007;Rabaey et al, 2008;Thrash et al, 2007;Virdis et al, 2008). Anodic and cathodic reactions can be coupled so that the anodic oxidation reaction generates sufficient power for cathodic reduction reactions to occur.…”

Section: Introductionmentioning

confidence: 99%

“…Anodic and cathodic reactions can be coupled so that the anodic oxidation reaction generates sufficient power for cathodic reduction reactions to occur. Combining anodic and cathodic reactions in a single BES holds promise for wastewater treatment because carbon and nitrogen can be removed simultaneously regardless of the C/N ratios in the waste streams (Clauwaert et al, 2007;Virdis et al, 2008Virdis et al, , 2009.…”

Section: Introductionmentioning

confidence: 99%

“…In two previous articles we have shown that microbial anodic acetate oxidation can power microbial cathodic nitrate reduction (Clauwaert et al, 2007;Virdis et al, 2008). To investigate differences in the engineering and operation of these systems, we used two reactor configurations in loop and nonloop formats (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

“…In the case of cathodic denitrification, researchers have considered using cathodes to generate hydrogen electrolytically or as a direct source of reducing equivalents for microbial respiration (Thrash and Coates, 2008). In previous studies of denitrifying cathodes, potentials at the cathode were measured above 0 V versus standard hydrogen electrode (Virdis et al, 2008;Clauwaert et al, 2007). At these potentials, the hydrogen partial pressure would theoretically be below 10 À14 atm (at pH 7), well below the known bacterial affinities for hydrogen (Virdis et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

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Bacterial community structure corresponds to performance during cathodic nitrate reduction

et al. 2010

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Microbial fuel cells (MFCs) have applications other than electricity production, including the capacity to power desirable reactions in the cathode chamber. However, current knowledge of the microbial ecology and physiology of biocathodes is minimal, and as a result more research dedicated to understanding the microbial communities active in cathode biofilms is required. Here we characterize the microbiology of denitrifying bacterial communities stimulated by reducing equivalents generated from the anodic oxidation of acetate. We analyzed biofilms isolated from two types of cathodic denitrification systems: (1) a loop format where the effluent from the carbon oxidation step in the anode is subjected to a nitrifying reactor which is fed to the cathode chamber and (2) an alternative non-loop format where anodic and cathodic feed streams are separated. The results of our study indicate the superior performance of the loop reactor in terms of enhanced current production and nitrate removal rates. We hypothesized that phylogenetic or structural features of the microbial communities could explain the increased performance of the loop reactor. We used PhyloChip with 16S rRNA (cDNA) and fluorescent in situ hybridization to characterize the active bacterial communities. Our study results reveal a greater richness, as well as an increased phylogenetic diversity, active in denitrifying biofilms than was previously identified in cathodic systems. Specifically, we identified Proteobacteria, Firmicutes and Chloroflexi members that were dominant in denitrifying cathodes. In addition, our study results indicate that it is the structural component, in terms of bacterial richness and evenness, rather than the phylogenetic affiliation of dominant bacteria, that best corresponds to cathode performance.

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Fuel Cells: Enzymes and Microbes for Energy Production

Barrière¹

2005

Encyclopedia of Inorganic Chemistry

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The use of redox enzymes and bacteria as catalysts at the electrodes of fuel cells is reviewed with an emphasis on some inorganic aspects of the research. In biofuel cells, redox enzymes catalyze the oxidation of organic substrates like glucose at the anode or the reduction of electron acceptors like dioxygen at the cathode. Many of the redox enzymes have metal‐active sites that are of interest to the bioinorganic chemist. Moreover, efficient electrical linking between a redox enzyme and an electrode requires the mediation of a small electroactive molecule, capable of diffusing and shuttling electrons between the core of the enzyme and the electrode surface. These redox mediators may be coordination or organometallic complexes. In microbial fuel cells, the biocatalysts are living microorganisms, most often bacteria. At the anode, the bacteria metabolize organic substrates like sugars or acetate. In the absence of dioxygen or other natural electron acceptors, some species of bacteria may transfer electrons to the anode of a fuel cell. Different mechanisms for bacterial anodic electron transfer are proposed and discussed in this article. One common feature of these processes is the direct or indirect linking of the electrode surface to the outer‐membrane‐bound electron‐transfer chain of the respiratory system of bacteria. This system contains a chain of redox enzymes containing cytochrome‐type active sites that may be directly electrochemically addressed in some cases. At the cathode of microbial fuel cell, some bacteria may also accept electrons and catalyze the reduction of electron acceptors like nitrate, sulfate, and dioxygen. Given the importance of dioxygen reduction in most fuel cells, a perspective is given on the way inorganic chemistry may contribute to the design of efficient electrode catalysts through molecular, material, enzymatic, or biological approaches. Finally, the prospect of self‐sustained biological fuel cell is discussed with integration of plants with their anolyte as an in situ fuel provider in the form of root exudates, or enrichment of dioxygen in their catholyte with photosynthetic activity of algae. Although the emphasis is on the inorganic themes of biological fuel cell research, the important multidisciplinary approaches of the topic are put forward. This article also contains discussions on the relative performances and applications of both types of biological fuel cells.

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Biological Denitrification in Microbial Fuel Cells

Cited by 756 publications

References 30 publications

Sequential anode–cathode configuration improves cathodic oxygen reduction and effluent quality of microbial fuel cells

Sequential anode–cathode configuration improves cathodic oxygen reduction and effluent quality of microbial fuel cells

Bacterial community structure corresponds to performance during cathodic nitrate reduction

Fuel Cells: Enzymes and Microbes for Energy Production

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