Five reactors were operated with low upflow superficial air velocities (0.41 cm min (1)) in order to observe granulation on synthetic wastewaters with different characteristics: 1) 340 mg-COD L (1); 2) 630 mg-COD L (1); and 3) 1300 mg-COD L (1). Stable granulation was only observed under low hydrodynamic shear for low-strength wastewater. 55-70% of soluble chemical oxygen demand (COD) was utilized before aeration and 91% COD, 62% total nitrogen (TN), and 96% total phosphorus (TP) were removed from the low-strength wastewater. Although medium-strength wastewater did generate granules they rapidly acquired a filamentous surface layer that resulted in decreased performance and loss of nitrification. 94% COD, 30% TN, and 85% TP were removed from the medium-strength wastewater. The high-strength wastewater did not develop granules and 85% COD was removed. Results demonstrated that high shear force was not required for granulation. Rather, granulation depended on multiple parameters to out-select rapidly growing aerobic microorganisms. (C) 2016 Elsevier Ltd. All rights reserved.