Role of hydrocyclone separator on the formation and separation of aerobic granular sludge: Evaluating granulation efficiency and simulating hydrodynamic behavior

•Hydrocyclone separator increased SVI but also decreased MLSS.•The effect of operation time of separator on granulation was weak.•The medium water velocity of 0.3 m/s was optimal for the separation.•The addition of carrier truly enhanced the granulating process.•The carrier with large particle size was proposed to be used for AGS cultivation.