Abstract
Anaerobic ammonium oxidation with nitrite to $N_2$(anammox) is a recently discovered microbial reaction with interesting potential for nitrogen removal from wastewater. Here we investigated the microbial community structure in the sequencing batch reactor(SBR) with an anammox activity. The SBR was optimized for the enrichment of a very slowly growing microbial community and showed that possibility of anaerobic ammonium oxidation. Fluorescence in situ hybridization(FISH) analysis revealed that anaerobic ammonium oxidizers were Candidatus Brocadia anammoxidans and Candidatus Kuenenia stuttgartiensis. Furthermore, Nitrosomol1as spp. of the ${\beta}$ -subclass of Proteobacteria was also present within the anaerobic SBR microorganisms.
