Nitrate reduction with biotic and abiotic cathodes at various cell voltages in bioelectrochemical denitrification system
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Electrochemical treatment of nitrate ions was attempted using different catalysts on the cathode in bioelectrochemical denitrification systems. The carbon cathode coated by biofilm (biocathode) could remove 91 % of nitrate ions at 1.0 V, which was almost same as the Pt-coated electrode (90 %). The exchange current density of biocathode was 0.0083 A/m2, which was almost 22 times higher than with an abiotic plain carbon cathode. The formation of intermediate products in nitrate reduction varied depending on the cell voltage. At 0.5 V, a large portion of nitrate was converted to ammonia, but at more increased cell voltage (0.7 and 1 V) a high amount of nitrite ions was found with little ammonia formation in cathodic solution. The maximum nitrate removal rate was 0.204 mg NO3-N/cm2d by biocathode, while plain carbon paper showed only 0.176 mg NO3-N/cm2d. Electrochemical analysis of chronoamperometry showed a higher stable current generation for biocathode (3.1 mA) and Pt-coated cathode (2.8 mA) as compared to plain carbon (0.6 mA) at 0.7 V of poised voltage.
KeywordsBioelectrochemical system Biocathode Nitrate reduction Electrochemical treatment Denitrification
The authors thank Kwang-Soon Choi, Jungmi Moon and Ramesh Kakarla for their help in during this work. This study was funded by Kyung Hee University—New researcher program. (Project number: 20090735).
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