Optimizing　reactor　design　and　understanding　aerobic　granular　sludge　metabolism　are　crucial　for　wastewater　treatment.　Unlike　previous　methods　where　each　column　operated　independently,　this　study　explored　floc　sludge　granulation　feasibility　and　stability　in　a　continuous　self-circulating　fluidized　bed　(AcOA-Zier)　reactor　with　aeration-induced　high-speed　liquid　sludge　circulation.　For　the　first　time,　granular　sludge　was　stratified　to　analyze　microbial　vertical　distribution　and　interactions.　Over　290　days　of　operation,　the　AcOA-Zier　reactor　successfully　granulated　sludge,　increasing　the　average　particle　diameter　from　93　to　378　mu　m　while　maintaining　a　low　SVI5　below　55　mL/g.　Throughout　the　granulation　process,　the　reactor　demonstrated　high　removal　efficiencies　for　COD　(95　%)　and　TN　(90　%).　Stratified　analysis　showed　the　third　layer　had　higher　microbial　diversity.　Methylotenera,　Ideonella,　g_unclassified_f_37-13,　and　g_unclassified_f_Saprospiraceae　were　predominantly　found　on　the　surfaces,　whereas　Hyphomicrobium,　996-1,　and　Nitrospira　were　more　abundant　near　the　granule　core.　The　abundance　of　g_unclassified_f_Anaerolineaceae,　SBR1031,　and　g_unclassified_f_A4b　reached　its　maximum　in　the　third　stratum.　Surface　microbes　removed　pollutants　and　secreted　extracellular　polymers.　Inner　microbes　underwent　denitrification　reaction　and　stored　nutrients　for　stability.　Metagenomics　identified　key　genes　(nxrB,　narG,　norB,　NRT)　driving　nitrogen　removal　via　nitrification,　denitrification,　and　assimilatory　nitrate　reduction.　Methylotenera,　g_unclassified_c_Betaproteobacteria,　and　Hyphomicrobium　were　identified　as　the　dominant　nitrogen-metabolizing　microorganisms.　This　study　offers　novel　insights　into　granular　sludge　microbial　spatial　organization　and　strategies　to　enhance　pollutant　removal,　advancing　sustainable　wastewater　treatment　technologies.