Modeling and simulation for citric acid fermentation by rotating disk contactor

摘要

A simle model was presented to describe the time courses of citric acid production by a rotating disc contactor (RDC) using Aspergillus niger. The model is expressed by Monod type cell growth, Luedeking-Piret type citric acid production rate equations and the diffusion equation for oxygen in the biofilm. The model contains five parameters, which were determined by the nonlinear least squares method by fittign the numerical solution to the experimental data. In solving the equations, the cell density of the biofilm was estiamted from the value of cellular mass per unit of biofilm area using an empirical equation. The experimental time courses in citric acid production period were well simulated with this model. The relation between the specific biofilm surface area and the rate of citric acid production was als explained by the simulation using the average values of five parameters of twelve runs.