Two-stage　Partial　nitritation/Anammox　(PN/A)　was　firstly　performed　for　recalcitrant　organics　(RO)-rich　thermal　hydrolysis　pretreated　anaerobic　digestion　(THP-AD)　centrate　treatment　with　municipal　wastewater　(MW)　as　co-substrate.　Results　indicated　the　inhibitory　effects　of　RO　was　alleviated　and　high　nitrate　issue　in　PN/A　effluent　was　addressed　by　cotreatment　strategy.　Stable　PN　with　nitrite　accumulation　ratio　of　95%　and　N　removal　efficiency　of　97.1%　were　well　maintained　at　MW　of　80%.　Nevertheless,　nitrate　accumulation　and　anammox　activity　loss　were　observed　with　lowering　MW　proportion　owing　to　the　weakened　denitrification　activity　and　aggravated　inhibitory　effect.　Microbial　analysis　revealed　Nitrosomonas　was　the　major　ammonium　oxidizing　bacteria　and　the　ideal　PN　performance　was　due　to　the　effective　out-selection　of　nitrite　oxidizing　bacteria.　Candidatus　Kuenenia　was　iden-tified　as　the　primary　bacteria　for　nitrogen　removal　(82.7%),　and　the　controlled　abundance　of　heterotrophic　denitrifiers　in　anammox　system　ensured　the　enhanced　nitrogen　removal　regardless　of　high　COD　loading　from　THP-AD　centrate.