ABSTRACT
This chapter focuses on sequencing batch reactor (SBR) operating parameter, cycle time and its effect on aerobic granulation, as well as on the characteristics of aerobic granules. Round aerobic granules first appeared in the SBR run at the cycle time of 3 hours after 30 cycles of operation, while irregular small granules were observed in the SBR operated at the cycle time of 12 hours after 120 cycles. It was found that the specific nitrification oxygen utilization rate was inversely related to the hydraulic selection pressure in terms of the SBR cycle time, that is, a shortened cycle time could stimulate the respiration activity of nitrifying bacteria. J. Wilschut and D. Hoekstra proposed that the strong repulsive hydration interaction was the main force keeping the cells apart, and when bacterial surfaces were strongly hydrophobic, irreversible adhesion would occur. The enhanced cell surface hydrophobicity and production of extracellular polysaccharides at short cycle time also contribute to rapid and successful aerobic granulation.
