CFD-PBM simulations the effect of aeration rates on hydrodynamics characteristics in a gas-liquid-solid aerobic fluidized bed biofilm reactor

A CFD-PBM coupling model was developed to simulate and calculate multiphase flow parameters, flow morphology, and bubble diameter in the aerobic fluidized bed biofilm reactor (AFBBR) under different aeration rates. The simulated radial solid volume fraction values were generally in agreement (within +/- 15%) with the experimental values. The gas phase predominantly occupied the central area of the reactor, with three distinct velocity peaks observed in the liquid and solid phases. Higher aeration rates improve the mixing of multiple phases by augmenting fluidization velocity, gas-phase volume fraction, eddies size, and turbulence characteristics, thereby leading to a rise in the average size of bubbles from 1.54 mm to 2.03 mm. However, the proportion of small diameter bubbles (0.27-1.03 mm) decreased from 69.4% to 59.6%. These studies concluded that the multiphase flow parameters under an aeration rate of 5.77 m3/(h & sdot;m3) were more favorable for improving oxygen mass transfer efficiency and reducing energy consumption.