Laboratory　experiments　were　carried　out　to　determine　the　long-term　effects　of　N-acyl-homoserine　lactone　(AHL)-based　quorum　sensing　on　the　characteristics　of　ANAMMOX　granules　in　high-loaded　reactors.　Results　clearly　showed　that　adding　30　mg　L-1　N-octanoyl-DL-homoserinelactone　(C-8-HSL)　at　the　initial　stage　(1-40　d)　of　the　experiment　had　long-term　positive　effects　on　the　settleability　of　granules　and　controlled　the　sludge　floatation　effectively.　C-8-HSL　decreased　the　content　of　bound　extracellular　polymeric　substances　(B-EPS)　and　the　ratio　of　protein　to　carbohydrate　(PN/PS)　by　17%　and　48%,　respectively　and　increased　the　relative　hydrophobicity　(RH)　of　the　granules　by　28%.　The　results　of　batch　tests　indicated　that　C-8-HSL　significantly　reduced　the　content　of　loosely-bound　EPS　(LB-EPS)　in　the　B-EPS,　which　was　responsible　for　variations　in　granule　settleability　and　stability.　Thus,　the　settleability　of　the　granules　was　improved　significantly　due　to　addition　of　C-8　-HSL,　contributing　to　operational　stability　and　the　high　TN　removal　efficiency　of　the　reactor.　On　day　150,　when　the　nitrogen　loading　rates　of　all　reactors　were　13.4　kg　TN　m(-3)　d(-1),　the　nitrogen　removal　rate　and　nitrogen　removal　efficiency　of　the　reactor　with　C-8-HSL　(R3)　were　up　to　11.2　kg　TN　m(-3)d(-1)　and　88%,　respectively.　N-hexanoyl-DL-homoserine　lactone　(C-6-HSL)　improved　activity　of　the　granules,　while　N-dodecanoyl-DL-homoserine　lactone　(C-12-HSL)　had　no　effect　on　the　characteristics　of　the　granules.　The　long-term　effects　of　C-8-HSL　on　the　settleability　of　granules　may　be　attributed　to　sustainable　release　of　endogenous　signals　induced　by　exogenous　signal.　(C)　2018　Elsevier　Ltd.　All　rights　reserved.