Dynamic modeling and simulation of a three-phase fluidized bed batch process for wastewater treatment

Batch operation with different starting substrate concentrations (biological oxygen demand (BOD₅)) and biomass concentrations (mixed liquor volatile solid (MLVS)) were performed on a completely mixed three-phase fluidized bed reactor used in treating simulated domestic waste water. The mixed culture microorganisms used were contained in a biofilm attaching to cement balls. The data obtained were fitted to five different kinetic rate equations. The kinetic parameters of each model were obtained using a Gauss - Newton nonlinear regression analysis method. It was found that the Haldane model incorporating endogenous metabolic consumption (Endo - Haldanc model), best described the kinetics of the biological reaction inside the three-phase fluidized bed reactor. This is due to the fact that this model can both account for the effects of cell death and/or endogenous metabolism at low concentration and of substrate inhibition at high concentration.