Evaluation of kinetic parameters of biochemical reaction in three-phase fluidized bed biofilm reactor for wastewater treatment

This study evaluates the kinetic parameters of biochemical reaction in thre e-phase fluidized bed biofilm reactor from the steady state values of the r esponse of the system to step changes in inlet concentration. It was observ ed from the outlet biological oxygen demand (BOD5) plot of the response of the system that as the inlet BOD5 was increased, the outlet BOD5 also incre ased, reached a peak value and then decreased until it leveled to a new ste ady state value corresponding to the new inlet concentration level. The inc rease in BOD5 was attributed to the accumulation of substrate within the re actor as well as the decrease in biofilm substrate consumption rate as the microorganisms adjusted to the new environment. Using the substrate balance at steady state and assuming Monod kinetics, an equation relating the subs trate consumption rate to substrate concentration (BOD5) and total biofilm surface area had been established. Monod kinetic parameters were found to b e K=2.20 g/m(2)/day, K-m=17.41 g/m(3) and K/K-m=0.13 m/day. The ratio K/K-m can be taken as the indicator for biofilm substrate degradation effectiven ess at low substrate concentrations. (C) 2000 Elsevier Science S.A. All rig hts reserved.