Diversity of nitrogen-removing microorganisms

This book chapter aims to address the microbial diversity associated with implementation prospects of nonconventional technologies for nitrogen removal in wastewater treatment plants. Special focus will be placed on the environmental advantages offered by these processes in contrast to conventional ones as heterotrophic denitrification and anammox. In addition, the operational and environmental conditions that promote the development of these microbial populations for nitrogen removal in wastewater will be addressed. Nitrate removal by an autotrophic process using sulfur compounds forms is the better characterized process and has been extensively applied in the treatment of wastewater with low C/N ratios rich in nitrates and sulfides. Hydrogenotrophic denitrification has attracted attention for application to nitrate removal from groundwater and industrial wastewater with very low organic matter content and high nitrate concentrations. This is because the process is clean, with a low biomass production and no residual organic matter. Anaerobic methanotrophic microorganisms using nitrate or nitrite (N-damo) have attracted attention for application in cooperation with anaerobic ammonia-oxidizing bacteria (anammox), resulting in the simultaneous removal of nitrogen (ammonium, nitrite, and nitrate) and methane.