Simultaneous removal of NH4+ and NO3– by coupling sulfur-based autotrophic denitrification and ANAMMOX with different electron donors

Unstable nitrite supply and low ammonia concentration limited the application of mainstream Anammox. In this study, sulfur-based autotrophic denitrification coupled Anammox system (SADA) was established with pyrite and sulfur as electron donors, respectively, to simultaneously remove NH4+-N and NO3–-N. More than 85 % of the total inorganic nitrogen removal efficiency was achieved with S0 as the electron donor. The synergistic nitrogen removal of autotrophic denitrification and Anammox reduced SO42− production. The average NH4+-N removal efficiency reached 94.73 % when pyrite was used as the electron donor, but the NO3–-N concentration in the effluent was higher than that in the influent. Microorganisms associated with nitrogen cycle were significantly enriched at the bottom of both reactors, where major biochemical processes occurred. Batch tests showed the coexistence of multiple N metabolic pathways in SADA, including Anammox, autotrophic denitrification, Sulfammox and Feammox. The genus Thiobacillus, Ferritrophicum, Candidatus_Brocadia, Ignavibacterium and Thermoanaerobaculum played major roles in nitrogen removal. © 2025