Denitrification process in microbial fuel cell: A comprehensive review

Nitrate contamination in water is hazardous to animals, human health, and environment. Biological denitrification is a lucrative method to curb nitrate pollution. Denitrification in conventional wastewater treatment processes is energy intensive. The process can become a part of waste to energy conversion systems such as microbial fuel cells (MFC). Researchers have looked at various aspects of MFC mediated denitrification, including different operating conditions, reactor configurations, presence/absence of oxygen, electron donor, and nitrate concentration. The highest nitrate removal of 99% is reported in MFC studies worldwide. Further scope lies in understanding heterogenous denitrifying bacteria's electroactivity, treating high strength wastes, long-term operation, mass balance modeling, and process control. This review summarizes the autotrophic and heterotrophic denitrification modes in an MFC, their electrochemical performance, nitrate removal rates, microbial community analysis, and denitrifying genes as molecular signatures of denitrification in MFC. The review article also discusses factors affecting the denitrification and prospects.