This　study　investigates　the　effects　of　continuous-feeding　and　step-feeding　patterns　on　the　nitrogen　removal　performance　and　the　aeration　rate　under　the　anoxic/aerobic(A/O)　condition　of　cyclic　activated　sludge　technology　(CAST)　process　treating　low　ρCOD/ρTN　wastewater,　and　analyzes　the　profiles　of　pH,　DO　and　ORP　under　the　step-feed　mode.　Results　show　that　the　average　removal　rate　of　ρTN　is　75.1%　and　SVI　is　229　mL/g　when　the　system　runs　under　the　continuous　feeding　mode,　and　activated　sludge　bulking　occurs　because　of　the　operation　under　long-term　condition　of　a　low　influent　load.　However,　the　average　removal　rate　of　ρTN　increases　to　81.5%　and　the　average　SVI　decreases　when　the　system　runs　under　the　step-feeding　mode.　Meanwhile,　the　aeration　rate　of　the　continuous-feeding　mode　is　0.56　m3/h　but　0.24　m3/h　under　the　step-feeding　mode　when　the　removal　rate　of　ρ(NH4+-N)　is　above　99%.　Consequently,　the　operation　cost　can　be　significantly　reduced　by　using　the　step-feeding　mode.　Furthermore,　pH,　DO,　ORP　curves　have　an　observe　variation　during　a　cycle　under　the　step-feed,　which　also　have　a　better　correlation　with　the　variation　of　contamination　in　the　system.