KINETIC-STUDY AND MATHEMATICAL-MODELING OF BIOFILM IN AN ANAEROBIC FLUIDIZED BED

The objectives in this study are to develop a layered model with attri tion for the growth process of biofilm in a methanogenic fluidized bed reactor, to discuss the possibility of existence of ''dormant'' bioma ss in the biofilm, and to estimate distributions of active biomass in the biofilm by the model. The model expresses characteristics and dist ributions of microorganisms inside the biofilm. Each substrate consump tion activity of attached, sloughed, and remaining biomasses is measur ed by batch experiments. Comparing their specific activities, the poss ibility of existence of ''dormant'' biomass in the biofilm is indicate d. Dormant biomass is inactive in the biofilm, but its activity recove rs by the supply of substrates. Based on results of the experiments, a layered biofilm model is developed, into which the concept of ''dorma nt'' biomass is incorporated. The accumulation process of active and d ormant biomasses in the biofilm is expressed by simulation with this n ewly developed model.