Abstract:To solve the problem that it takes a long time to cultivate granular sludge under single load or gradually increasing load and the removal of pollutants is unstable. An alternative change of influent carbon-nitrogen loading was proposed to study the formation process of aerobic granular sludge (AGS) and the removal effect of pollutants. Cultivated AGS by influent-aeration-sedimentation-drainage (S1) and influent- aeration-anoxia-aeration-anoxia-aeration-sedimentation-drainage (S2), and the morphological changes, sedimentation performance and pollutant removal situation during the formation of granular sludge were compared and analyzed. Results showed that the average particle size of the reactor (S1) was 0.5 mm on Day 84 and the reactor (S2) on Day 78. At the Day 115, the average particle size of the sludge in two reactors was 0.85 mm and 0.97 mm.S1 and S2 mass concentration of the MLSS is 4.940, 5.895 g/L and SVI in the reactor is 80, 46 mL/g, mature AGS was more conducive to the growth of microorganisms, maintained higher biomass and sedimentation performance.The removal effect of COD and NH₄⁺-N under two operating modes changed slightly, and the removal effect of TN and PO₄^3--P was significantly different. The removal rates of COD, NH₄⁺-N, TN, and PO₄^3--P in S1 operation mode were 90.0%, 99.7%, 74.5% and 85.0% spectively, while were 94.0%, 99.9%, 94.35%, 95.0%, respectively, in S2, and 4.0%, 0.2%, 19.9% and 10.0% higher than that in S1. The aerobic granular sludge with larger particle size and better pollutant removal performance Could be cultivated in reactor (S2) with intermittent aeration.