Biofluid mechanical investigations in sequencing batch reactor (SBR)

In the present contribution experimental and numerical investigations of multiphase flow in a sequencing batch reactor (SBR) are presented. In the bioreactor the formation and growth of granular activated sludge (GAS) with diameter up to 5 mm occurs. In order to experimentally analyse multiphase flow patterns in a mixture of water, air and granules in the SBR, optical in situ techniques are applied. Particle image velocimetry (PIV) and particle tracking velocimetry (PTV) are employed to observe the velocity fields of fluid and granules. For the three-dimensional numerical simulation of the flow problem the Euler–Euler approach is used. The comparison of experimental and numerical results shows a lot of similarities. The characteristic flow patterns can be observed in three zones of the SBR. It can be shown that effect of normal strain rate up to ε˙=15s-1 and shear strain rate up to γ˙=15s-1, besides biochemical activities have a major influence on the formation, shape and size of the granules in the SBR under aerobic conditions.