Microbial community composition, dynamics, and biogeochemistry during the start-up of a partial nitritation-anammox pathway in an upflow reactor

The dynamics of the microbial community and functional taxa related to nitrogen (N) removal biogeochemical processes can be important to the development of new cost-effective processes in wastewater treatment. This work consisted of the start-up of an upflow reactor for N-removal by partial nitritation/anammox pathway, working at ambient temperature, during 397 d. After an adaptation to the reactor operational conditions, a stable total N-removal (52% efficiency) was linked to ammonium deletion. High-throughput sequencing of 16S rRNA gene amplicons analysis revealed a relative abundance of about 1% of anammox genus Candidatus Brocadia after 397 d. Nitrosomonas, a nitrifying bacterium also increased the relative abundance, together with the accretion of relative numbers of Denitratisoma and Thiobacillus, recognized as heterotrophic and chemolithoautotrophic denitrifying bacteria, respectively. These findings provide a better understanding of the N-removal by key microbial groups that may be useful to optimize future field application of systems working at ambient temperature.