Bioremediation of nitrate‐polluted groundwater in a microbial fuel cell

<jats:title>Abstract</jats:title><jats:sec><jats:title>BACKGROUND</jats:title><jats:p><jats:bold>Groundwater quality is threatened by nitrate accumulation in several regions around the world. Nitrate must be removed from contaminated groundwater to use it as drinking water. Microbial fuel cells (<jats:styled-content style="fixed-case">MFCs</jats:styled-content>) can be used for autotrophic denitrification. Thus, the use of <jats:styled-content style="fixed-case">MFCs</jats:styled-content> is a potential alternative to using traditional methods for treating nitrate‐polluted groundwater</jats:bold>.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p><jats:bold>The objective of this study was to evaluate the potential of <jats:styled-content style="fixed-case">MFC</jats:styled-content> technology to treat nitrate‐polluted groundwater (28.32 ± 6.15 <jats:styled-content style="fixed-case">mgN‐NO<jats:sub>3</jats:sub></jats:styled-content><jats:sup>−</jats:sup> L<jats:sup>−1</jats:sup>). The bioanode was fed with an acetate solution that permitted electron and proton flux to the biocathode. Initially, nitrite was observed in the effluent. After 97 days of operation, the denitrifying‐<jats:styled-content style="fixed-case">MFC</jats:styled-content> reduced the nitrate and nitrite concentrations in the effluent (12.14 ± 3.59 <jats:styled-content style="fixed-case">mgN‐NO<jats:sub>3</jats:sub></jats:styled-content><jats:sup>−</jats:sup> L<jats:sup>−1</jats:sup> and 0.14 ± 0.13 <jats:styled-content style="fixed-case">mgN‐NO<jats:sub>2</jats:sub></jats:styled-content><jats:sup>−</jats:sup> L<jats:sup>−1</jats:sup>).Thus, this method improved water quality to meet World Health Organisation standards. However, nitrous oxide emissions were deduced from the electron balance, cathode coulumbic efficiency and Tafel plots. Bioelectrochemical evolution of the biocathode was related to the denitrification nature (sequential reaction steps from <jats:styled-content style="fixed-case">NO<jats:sub>3</jats:sub></jats:styled-content><jats:sup>−</jats:sup> to <jats:styled-content style="fixed-case">N<jats:sub>2</jats:sub></jats:styled-content>, through <jats:styled-content style="fixed-case">NO<jats:sub>2</jats:sub></jats:styled-content><jats:sup>−</jats:sup> and <jats:styled-content style="fixed-case">N<jats:sub>2</jats:sub>O</jats:styled-content> as stable intermediates) and was supported by the Tafel plots</jats:bold>.</jats:p></jats:sec><jats:sec><jats:title>CONCLUSION</jats:title><jats:p><jats:bold>The bioremediation of nitrate‐polluted groundwater with a <jats:styled-content style="fixed-case">MFC</jats:styled-content> biocathode is feasible. © 2012 Society of Chemical Industry</jats:bold></jats:p></jats:sec>