Identification of bacterial communities in conventional wastewater treatment sludge to inform inoculation of the anammox process.

This study uses 16 S rRNA gene pyrosequencing for the identification of a vast number of wastewater bacterial communities to investigate the evolution of bacterial communities in the Anammox process. Four lab-scale Anammox reactors inoculated with different conventional wastewater treatment sludge (activated sludge, livestock wastewater treatment sludge, denitrification sludge, and anaerobic digestion sludge) were operated under identical operating conditions for more than 400 days. The phylum Planctomycetes was present in all seeds of conventional sludge with a relative abundance of 1-3%. In particular, the known Anammox bacteria Candidatus Brocadia was found in the seed of the denitrification sludge. The reactor inoculated with denitrification sludge demonstrated the most effective nitrogen removal of ∼80% with successful cultivation of Anammox bacteria. This study found that the performance of the Anammox process is related to the presence of Nitrospira genus (nitrite-oxidizing bacteria) and that symbiotic association with other functional groups can lead to nitrogen removal. The outcomes of this study can provide vital insight into the study of microbial ecology for the cultivation of Anammox bacteria.