Denitrification process in microbial fuel cell: A comprehensive review

Aerobic denitrification with an electrode as the sole electron and energy source

“…Consequently, it is commonly speculated that bioelectrochemical nitrate removal under aerobic conditions is feasible only due to the existence of anaerobic microenvironments that prevent denitrifying bacteria from being in direct contact with oxygen. 23,29,[33][34][35] Contrary to this, in this work we demonstrate that an electrode can indeed act as the sole source of electrons and energy under aerobic conditions. Our results suggest that electro-active denitrifying bacteria can not only tolerate oxygen but also use it as an electron acceptor while using the cathode as the sole electron and energy source.…”

“…1) are lower than those reported in the literature which are commonly in the order of 100 g N-NO 3 m −3 d −1 under autotrophic conditions. 23 It has to be noted that volumetric removal could be easily improved by increasing the electrode area to volume ratio (using electrodes with large surface area), but this was out of the scope of this work.…”

“…21,22 In this process, the electrode (cathode) acts as an inexhaustible electron source avoiding the need for a continuous supply of external chemical compounds for denitrification of wastewater with low availability of carbon sources. [23][24][25][26][27] Furthermore, the application of bioelectrochemical denitrification under aerobic conditions allows ammonia removal to be performed in the same reactor. When this is applied under heterotrophic conditions, organic carbon competes with the electrode as the electron donor, reducing the influence of electro-active bacteria on nitrate removal.…”

“…21,22 In this process, the electrode (cathode) acts as an inexhaustible electron source avoiding the need for a continuous supply of external chemical compounds for denitrification of wastewater with low availability of carbon sources. 23–27…”

“…Consequently, it is commonly speculated that bioelectrochemical nitrate removal under aerobic conditions is feasible only due to the existence of anaerobic microenvironments that prevent denitrifying bacteria from being in direct contact with oxygen. 23,29,33–35…”