New perspectives on microbial communities and biological nitrogen removal processes in wastewater treatment systems

Yi Ren^a,b, Huu Hao Ngo^b, Wenshan Guo^b, Dongbo Wang^c,d, Lai Peng^e, Bing-Jie Ni^b, Wei Wei^b, Yiwen Liu^a,b

School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China.

Abstract

Biological nitrogen removal (BNR) is a critical process in wastewater treatment. Recently, there have new microbial communities been discovered to be capable of performing BNR with novel metabolic pathways. This review presents the up-to-date status on these microorganisms, including ammonia oxidizing archaea (AOA), complete ammonia oxidation (COMAMMOX) bacteria, anaerobic ammonium oxidation coupled to iron reduction (FEAMMOX) bacteria, anaerobic ammonium oxidation (ANAMMOX) bacteria and denitrifying anaerobic methane oxidation (DAMO) microorganism. Their metabolic pathways and enzymatic reactions in nitrogen cycle are demonstrated. Generally, these novel microbial communities have advantages over canonical nitrifiers or denitrifiers, such as higher substrate affinities, better physicochemical tolerances and/or less greenhouse gas emission. Also, their recent development and/or implementation in BNR is discussed and outlook. Finally, the key implications of coupling these microbial communities for BNR are identified. Overall, this review illustrates novel microbial communities that could provide new possibilities for high-performance and energy-saving nitrogen removal from wastewater.

Keywords: Biological nitrogen removal (BNR), Ammonia oxidizing archaea (AOA), complete ammonia oxidation (COMAMMOX), anaerobic ammonium oxidation (ANAMMOX), denitrifying anaerobic methane oxidation (DAMO).