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

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%, < 0.2% and 10.9%, respectively. Salinity variations impelled the dynamics of Anammox bacteria. Jettenia shifted to Brocadia and Kuenenia at salinity of 0.61%-0.81%. Kuenenia outcompeted Brocadia and occupied 51.5% and 50.9% at salinity of 1.48%-1.54% and 2.96%-3.10%, respectively. High nitrite affinity and fast growth rate were proposed as key factors fostering Brocadia overgrew Jettenia. Functionalities of sodium-motive-force facilitated energy generation and intracellular osmotic pressure equilibrium regulation crucially determined Kuenenia's dominance at elevated salinity. Co-occurrence network further manifested beneficial symbiotic relationships boosted Kuenenia's preponderance. Knowledge gleaned deepen understanding on survival niches of freshwater Anammox genera at saline environments and lead to immediate benefits to its applications treating relevant wastewaters.

Automated summary

Partial nitritation/Anammox was effectively applied to treat NaCl-amended landfill leachate, achieving robust nitrogen removal at varying salinities. The dynamics of Anammox bacteria were influenced by salinity variations, with different genera exhibiting dominance under different salinity levels. Key factors such as high nitrite affinity and specific functionalities facilitated certain bacteria's dominance in saline environments, enhancing the efficiency of nitrogen removal processes. Co-occurrence networks indicated beneficial symbiotic relationships contributing to the dominance of specific genera.