Sulfidation forwarding high-strength Anammox process using nitrate as electron acceptor via thiosulfate-driven nitrate denitratation

[Display omitted] •High TN removal (83.66%) was achieved at the NLR of 2.6 kg-N/(m3·d) in TDSA.•Sulfate production was greatly reduced in TDSA system.•Unique S0@ Anammox granules could tolerate high FA and DO.•The contributions of various nitrogen removal pathways were investigated.•Nitrogen and sulfur conversion mechanism in TDSA system was proposed. A single up-flow thiosulfate-driven nitrate denitratation coupled with the sulfurized Anammox (TDSA) with the core–shell structure (S0@ Anammox granules) provided a chemical/energy-saving way for the removal of high-content ammonium with nitrate as electron acceptor. Approximately 83.66% total nitrogen removal efficiency (TNRE) could be achieved by the sulfurized Anammox encrusted by S0/Sn2− at a high loading rate (2.6 kg-N/(m3·d)) via resisting high concentration of free ammonia (FA) (22.35 mg/L), mainly through S2O32−, S0/Sn2− -driven partial denitrification-Anammox (PDN-Anammox) process. Moreover, S0/Sn2−-PDN-Anammox was largely restricted when intermittently aerated, but still resulting in 74.47% TNRE due to the partial nitrification-Anammox (PN-Anammox). The sequencing analysis revealed that Anammox bacterium (Candidatus_Kuenenia) and sulfur-oxidizing bacterium (Thiobacillus) coexisted, in which Anammox process occurred mainly via NO instead of NH2OH. This study provided a new perspective for high concentration nitrogen wastewater removal in engineering applications.