In　this　study,　a　continuous-flow　system　with　enhanced　biological　phosphorus　removal　(EBPR)　granules　was　operated　at　different　COD　concentrations　(200,　300　and　400　mg　L-1)　to　investigate　the　effect　of　COD　loading　on　this　system.　The　results　showed　that　when　the　COD　concentration　in　influent　was　increased　to　400　mg　L-1,　the　anaerobic　COD　removal　efficiency　and　total　phosphorus　removal　efficiency　reduced　obviously　and　the　settling　ability　of　granules　deteriorated　due　to　the　proliferation　of　filamentous　bacteria.　Moreover,　high　COD　loading　inhibited　the　EPS　secretion　and　destroyed　the　stability　of　granules.　Results　of　high-through　pyrosequencing　indicated　that　filamentous　bacteria　had　a　competitive　advantage　over　polyphosphate-accumulating　organisms　(PAOs)　at　high　COD　loading.　The　performance　of　system,　settling　ability　of　granules　and　proportion　of　PAOs　gradually　recovered　to　the　initial　level　after　the　COD　concentration　was　reduced　to　200　mg　L-1　on　day　81.　(C)　2016　Elsevier　Ltd.　All　rights　reserved.