Anaerobic　ammonia　oxidation　(Anammox)　has　garnered　growing　attention　as　an　energy-efficient　bioprocess.　However,　the　sustainable　provision　of　nitrite　remains　a　crucial　challenge.　This　study　aimed　to　assess　a　promising　alternative　to　existing　partial　nitrification-　and　heterotrophic　partial　denitrification　(PDN)-based　Anammox　processes　by　substituting　the　nitrite　supply　with　autotrophic　sulfur-driven　PDN.　After　200　days,　the　desirable　nitrogen　removal　efficiency　of　96.1%　was　obtained　in　the　S-PDN　coupling　Anammox　process　(S-PDN/A)　with　a　high-quality　effluent　total　nitrogen　of　3.1　mg　N/L.　Additional　experiments　identified　S-PDN/A　as　a　stepwise　reaction　with　generated　S0　as　an　intermediate.　Initially,　S2-　was　oxidized　to　S0　[21.2　mg　of　S/(g　of　SS·h)],　coupled　with　ultrafast　denitrification　[NO3-　→　N2,　3.9　mg　of　N/(g　of　SS·h)].　Subsequently,　S0　served　as　an　electron　donor　for　S-PDN　(NO3-　→　NO2-),　efficiently　facilitating　Anammox　as　the　dominant　nitrogen　removal　pathway　contributing　up　to　71.0%　with　a　reaction　rate　of　1.7　mg　N/(g　SS·h).　Distinct　from　reported　prevalence　of　Candidatus　brocadia　in　the　Anammox　technology　for　low-strength　wastewater　treatment,　Candidatus　kuenenia　(0.12%　→　3.4%)　unexpectedly　triumphed　due　to　unique　ecological　niche　provided　by　S-PDN.　S-PDN/A　offers　fresh　insights　into　Anammox　application,　enabling　a　potential　reduction　of　up　to　100%　in　organics　demand,　43.0%　savings　in　aeration　energy　consumption,　and　69.9%　decrease　in　biomass　generation　when　compared　to　conventional　bioprocesses.　©　2024　American　Chemical　Society.