Fluidized Bed Biofilm Reactor (FBBR)Kinetics – A Rational Design and Optimization Approach

Abstract

A mathematical model is presented for an intrinsic zero order, completely mixed fLuidized bed biofilm reactor(FBBR). Intrabiofilm mass transfer effects are considered. A modified Thiele modulus(ϕm) is defined to relate substrate conversion rate to intrabiofilm mass transfer rate through use of an effectiveness factor(η). For ϕm− < 1.15, intrabiofilm mass transfer is insignificant and intrinsic zero order kinetics is observed. For ϕm > 1.15, the FBBR substrate conversion rate is mass transfer limited and 0.45 order kinetics is observed. It is demonstrated via the FBBR model that media size and density and biofilm thickness are the most significant design parameters affecting FBBR performance. Selection of these parameters can be optimized through use of the equations presented herein. In addition, the effect of other important design parameters such as recycle rate and superficial upflow velocity on reactor performance can be assessed using the FBBR model outlined here.