Nitrogen recovery from wastewater using microbial fuel cells

Nitrogen is one of major contaminants in wastewater; however, nitrogen, as bio-elements for crop growth, is the indispensable fertilizer in agriculture. In this study, two-chamber microbial fuel cells (MFCs) were first operated with microorganisms in anode chamber and potassium ferricyanide as catholyte. After being successfully startup, the two-chamber MFCs were re-constructed to three-chamber MFCs which were used to recover the NO3- - N and NH4+ - N of synthetic wastewater into value-added nitrogenous fertilizer from cathode chamber and anode chamber, respectively. Ferric nitrate was used as the sole electron acceptor in cathode, which also was used to evaluate the NO3- - N recover efficiency in the case major anion of NO3- in cathode. The output voltage of these MFCs was about 600-700 mV at an external load of 500 Omega. About 47% NH4+ - N in anode chamber and 83% NO3- - N in cathode chamber could be recovered. Higher current density can selectively improve the recovery efficiency of both NH4+ - N and NO3- - N. The study demonstrated a nitrogen recovery process from synthetic wastewater using three-chamber MFCs.