Analysis of a continuous, aerobic, fixed‐film bioreactor. II. Dynamic behavior

Abstract

The dynamic analysis of a continuous, aerobic, fixed-film bioreactor has been performed. Rigorous mathematical models have been developed for a fluidized-bed fermentor with biofilm growth. The transient performance of the reactor is appraised in terms of outlet penicillin concentration for constant, as well as variable carbon substrate feed rates. The effect of the reactor oxygen transfer capacity is elucidated for those cases employing substrate feeding strategies. The results show that penicillin production in a continuous, fixed-film bioreactor reaches a maximum with processing time, but subsequently decreases as cell mass accumulates and substrate deficiencies occur. The maximum production level can be maintained for increased operating times if the substrate supply is continuously increased. The duration of this prolonged production is a direct function of the rate of increase and the operating time at which the increase is initiated. The oxygen transfer capacity of the reactor was found to be important to the effectiveness of a feeding strategy.

Improved modelling of the unsteady‐state behaviour of an immobilized‐cell, fluidized‐bed bioreactor for phenol biodegradation

“…A few unsteady state 1 -dimensional biofilm models have been previously proposed for ICFBRs (Worden and Donaldson, 1987;Tang et al, 1987;Park et al, 1984;Cadani et al, 1993). However, these models have several limitations as follows: 1.…”

“…Some of the models (Park et al, 1984;Tang et al, 1987) have a large number of parameters, many of which cannot be determined independently. In order to address the limitations of existing ICFBR models, this research proposes a new 1 -dimensional mathematical model for the unsteady state response of an ICFBR subjected to changes in organic loading of a single inhibitory substrate, phenol.…”

Prediction of optimal biofilm thickness for membrane-attached biofilms growing in an extractive membrane bioreactor

“…Often, investigators have neglected the influence of cell maintenance, cell decay, and/or cell detachment (biofilm attrition), factors which may prove useful in controlling biofilm thickness. For example, Park et al (1984) suggested that maximum biofilm thickness occurs when substrate supply balances cell maintenance requirements, but biomass detachment was not taken into account. Benefield and Molz (1985) simplified their model by assuming pseudo steady state in the biofilm, and did not account for the shear stress on the surface of the biofilm.…”

“…Dynamic models which allow for biofilm growth have been used to describe and study different types of biofilm reactors (Benefield and Molz, 1985;Park et al, 1984;SBez and Rittmann, 1988;Skowlund, 1990;Wanner and Gujer, 1986). Often, investigators have neglected the influence of cell maintenance, cell decay, and/or cell detachment (biofilm attrition), factors which may prove useful in controlling biofilm thickness.…”

Mathematical Modelling and Stationary Characteristics of a Two-Phase Fluidised-Bed Bioreactor With External Aeration

“…These bioreactors are applied to the microbiological degradation of toxic organic compounds (Onysko et al, 2002;Tang and Fan, 1987a;Tang et al 1987b;Wisecarver and Fan, 1989;Worden and Donaldson, 1987), the microbiological nitrification process (Dunn et al, 1983), and the synthesis of some drugs, e.g. penicillin, oxytetracycline, and other organic compounds (Park et al, 1984). A review of numerous applications of fluidised bed bioreactors is given by Schügerl (1997).…”