Parameteridentifi-SE:7

Biochemical reactions can often be formulated mathematically as ordinary di#erential equations. In the process of modeling, the main questions that arise are concerned with structuralidentifiE ility, parameter estimation and practical identifienti1-E To clarify these questions and the methods how to solve them, we analyze two di#erent second order models for anaerobic waste water treatment processes using two data sets obtained from di#erent experimental setups. In both experiments only biogas production rate was measured which complicates the analysis considerably. We show that proving structural identifienti1H of the mathematical models with currently used methods fails. Therefore, we introduce a new, general method based on the asymptotic behavior of the maximum likelihood estimator to show local structuralidentifi - ability. For parameter estimation we use the multiple shooting approach which is described. Additionally we show that the Hessian matrix approach to compute confiF7HA intervals fails in our examples while a method based on Monte Carlo Simulation works well. # 2002 Elsevier Science Inc. All rights reserved