Effects of loading rates and N/S ratios in the sulfide-dependent autotrophic denitrification (SDAD) and Anammox coupling system

[Display omitted] •A novel SDAD-Anammox process was developed for nitrogen and sulfide removal.•The TN removal efficiency achieved 86.7% at the NLR of 1.52 kg N m−3 d−1.•Sulfide removal efficiency reached 100% throughout the whole process.•Anammox dominated with the aid of PSDAD and always competed over SSDAD.•Anammox bacteria kept active despite a relatively low abundance. This study investigated the shock resistance and the stability of a novel sulfide-dependent autotrophic denitrification (SDAD) and anaerobic ammonium oxidation (Anammox) coupling process for simultaneous removal of sulfide and nitrogen-containing wastewater in a single reactor. Results show that the total nitrogen (TN) removal efficiency reached 86.7% at a nitrogen loading rate (NLR) of 1.52 kgN m−3 d−1. Sulfide was fully oxidized, achieving the removal efficiency of 100% throughout the whole process. Batch tests suggest that Anammox remained dominant with the cooperation of partial SDAD (PSDAD) and could always compete over short-cut SDAD (SSDAD) for nitrite. High-throughput sequencing analysis revealed that Anammox bacteria remained active despite a relatively lower abundance and diversity than denitrifying bacteria. Candidatus Kuenenia might be the main contributor to Anammox, while Thiobacillus and Sulfurimonas were closely related to SDAD.