Forward-­Backward Propagation to Identify the Maximum Specific Growth Rates of a Bioreactor

Abstract

In this article, we are interested in identifying the parameters of an aerobic bioprocess modelused for wastewater treatment. In the field of biotechnology, various computer bugs caused by roundingerrors can induce an error interval that is too wide during data acquisition. For this reason, weare testing a new identification method using a set method based on interval arithmetic. The processstudied is the chemical transformation of ammoniacal nitrogen which takes place in two stages: Reactionof nitrificationdenitrification.The parameters chosen for the identification are the yields andthe maximum growth rates. Initially, the study of observability by a differential algebraic method willsimplify the study of the mathematical model. This nonlinear model is described by six differentialequations. Subsequently, we apply a set method, in particular the propagation of constraints also calledforwardbackward propagation, this technique allowed us to determine intervals containing the variablereturns as well as the maximum specific growth rates defined from the Monod model which describesthe operation of the bioreactor. This method also guarantees the result by rejecting all inconsistentvalues.