The　granule-based　partial-denitrification　(PD)　reactor　can　achieve　an　efficient　nitrite　production　for　anammox　process.　In　this　study,　the　PD　granules　were　successfully　cultivated　in　a　sequencing　batch　reactor　(SBR),　the　physicochemical　properties　and　microbial　activities　were　characterized　at　increasing　nitrate　loading　rate　(NLR).　Results　indicated　that　high　NLR　benefited　the　PD　for　nitrite　production,　and　a　more　dense　and　compact　granule　can　be　developed　at　the　NLR　of　0.24-0.48　Kg　N/m(3)/d.　Whereas　the　settling　ability　decreased　when　the　NLR　increased　to　0.96　Kg　N/m(3)/d,　which　was　likely　caused　by　the　decrease　of　proteins　(PN)　in　extracellular　polymeric　substances　(EPS)　content　and　the　increase　of　loosely　bound　EPS　(L-EPS)　fraction.　Besides,　the　characterization　of　size-fractionated　PD　granules　revealed　that　a　better　settling　ability　was　generally　obtained　with　larger　granules　except　for　the　size　of　d　＞　3.35　mm,　which　the　settling　velocity　was　reduced,　likely　attributed　to　the　excess　L-EPS　fraction　(56.3%)　and　presence　of　empty　capsule　inside　granules.　The　smaller　granules　exhibited　higher　microbial　activities　due　to　the　favorable　mass　transfer,　the　nitrate　reduction　rate　was　as　high　as　152.6　mg　N/h/g　VSS　with　granules　of　d　＜　1.0　mm.　Results　obtained　in　this　study　provided　a　better　understanding　of　the　properties　of　PD　granules　and　would　be　helpful　for　the　future　development　of　granule-based　PD　reactor　in　achieving　an　efficient　and　stable　nitrite　production.　(C)　2019　Elsevier　B.V.　All　rights　reserved.