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Enhanced nitrogen removal in single‐chamber microbial fuel cells with increased gas diffusion areas
Author(s) -
Yan Hengjing,
Regan John M.
Publication year - 2013
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.24769
Subject(s) - microbial fuel cell , ammonia , cathode , chemistry , diffusion , faraday efficiency , nitrogen , volumetric flow rate , diffusion layer , electrochemistry , oxygen , analytical chemistry (journal) , environmental chemistry , electrode , organic chemistry , thermodynamics , physics , anode
Abstract Single‐chamber microbial fuel cells (MFCs) with nitrifiers pre‐enriched at the air cathodes have previously been demonstrated as a passive strategy for integrating nitrogen removal into current‐generating bioelectrochemical systems. To further define system design parameters for this strategy, we investigated in this study the effects of oxygen diffusion area and COD/N ratio in continuous‐flow reactors. Doubling the gas diffusion area by adding an additional air cathode or a diffusion cloth significantly increased the ammonia and COD removal rates (by up to 115% and 39%), ammonia removal efficiency (by up to 134%), the cell voltage and cathode potentials, and the power densities (by a factor of approximately 2). When the COD/N ratio was lowered from 13 to 3, we found up to 244% higher ammonia removal rate but at least 19% lower ammonia removal efficiency. An increase of COD removal rate by up to 27% was also found when the COD/N ratio was lowered from 11 to 3. The Coulombic efficiency was not affected by the additional air cathode, but decreased by an average of 11% with the addition of a diffusion cloth. Ammonia removal by assimilation was also estimated to understand the ammonia removal mechanism in these systems. These results showed that the doubling of gas diffusion area enhanced N and COD removal rates without compromising electrochemical performance. Biotechnol. Bioeng. 2013; 110: 785–791. © 2012 Wiley Periodicals, Inc.