Estimation of state variables and kinetic parameters in an enzyme production process by using minimal modelling

An estimation methodology is proposed to estimate the states and some kinetic parameters in a lipase production process. The state vector is composed of the biomass -X- and two substrates, an intracellular one -Sin- and an extracellular one -So-. It is estimated by an online measurement of the oxygen uptake rate. As the problem is too complex to be solved by a single stable observer, the estimation problem is divided in three subproblems, solved by estimation algorithms proved to be convergent. These algorithms use a minimal modelling of the process. It provides the estimation of the whole state and of two kinetic parameters, the specific biomass growth rate and the absorption rate of the substrate by the cells, considering the general equations of the dynamical model and the mass balance of the substrate in the bioreactor. This paper presents the design of the estimation algorithms and discusses their results in simulation and on experimental data from a pilot plan