Enrichment of Ca. Jettenia in sequencing batch reactors operated with low nitrogen loading rate and high influent nitrogen concentration

[Display omitted] •Anammox enrichment was conducted to treat low nitrogen loading wastewater.•Increasing nitrogen loading enhanced activity and abundance of anammox bacteria.•Candidatus Jettenia was the most dominant anammox genus in the enrichment.•AnAOB dynamics was correlated with the operational factors and performance.•Resilience of Candidatus Jettenia to nitrogen loading shocks was scrutinized. To apply the anammox processes into the mainstream of domestic wastewater treatment plants, two laboratory-scale sequence batch reactors have been developed and used with two different activated sludges seeded in each sequence batch reactors with gradually increases influent total nitrogen concentrations under low nitrogen loading rates. During 320 days of operation, both sequence batch reactors showed high specific anammox activity (0.68 – 0.75 kgN kg−1VSS d−1) and a nitrogen removal efficiency of 97.50%. To monitor changes in microbial community dynamics during enrichment, high-throughput sequencing analysis was performed. Members taxonomically affiliated with Candidatus Jettenia were markedly enriched and predominant in both sequence batch reactors in response to the increasing influent total nitrogen concentrations. These results suggest that Candidatus Jettenia might be a prominent anammox genus under low nitrogen loading rate with high total nitrogen concentration conditions and could be suitably applied to the mainstream process of domestic wastewater treatment systems.