Probing the dynamics of three freshwater Anammox genera at different salinity levels in a partial nitritation and Anammox sequencing batch reactor treating landfill leachate

[Display omitted] •PN/A achieved robust NRRs of 0.97 ± 0.05 kg N/m3/d with leachate at salinity of 3%.•High affinity for nitrite and fast growth rate determined the dominance of Brocadia.•Kuenenia conquered Brocadia owing to merits of Na+ regulation and smf utilization.•Beneficial symbiotes boosted Kuenenia’s dominance at high salinity.•Salt-adapted FAB could be superior than MAB to treat NH4+-rich saline wastewater. Partial nitritation/Anammox was applied to treat NaCl-amended landfill leachate. The reactor established robust nitrogen removal of 85.7 ± 2.4% with incremental salinity from 0.61% to 3.10% and achieved 0.91–1.05 kg N/m3/d at salinity of 2.96%–3.10%. Microbial community analysis revealed Nitrosomonas, Nitrospira, and denitrifiers occupied 4.1%,