Guilherme Araujo Pimentel

Design, analysis and validation of a simple dynamic model of a submerged membrane bioreactor

In this study, a simple dynamic model of a submerged membrane bioreactor (sMBR) is proposed, which would be suitable for process control. In order to validate the proposed model structure, informative data sets are generated using a detailed simulator built in a well-established environment, namely GPS-X. The model properties are studied, including equilibrium points, stability, and slow/fast dynamics (three different time scales). The existence of slow-fast dynamics is central to the development of a dedicated parameter estimation procedure. Finally, a nonlinear model predictive control is designed to illustrate the potential of the developed model within a model-based control structure. The problem of water treatment in a recirculating aquaculture system is considered as an application example.

Controle robusto por realimentação linearizante parcial de bioreatores em modo de operação descontínua com alimentação

A methodology for the robust control design of a class of bioreactors operating in fed-batch mode is proposed. Firstly, a general model is presented to describe the growing dynamics of the bacteria Escherichia Coli and the yeast Saccharomyces Cerevisiae cultures, which are the most employed microorganisms applied in biotechnological industry. From this model, the paper proposes a control law that regulates the by-product concentration in small levels (i.e., close to zero) aiming to maximize the biomass concentration. To this end, the nonlinear dynamics of the bioreactor is rewritten in terms of time-varying parameters (quasi-LPV approach) in order to apply the linear matrix inequality framework for designing the free dynamics resulting from a partial feedback linearizing strategy. The proposed design conditions provide the robust stability of the closed-loop system while ensuring some performance w.r.t. disturbance signals. To verify the behavior of the closed-loop system, several simulation based tests are carried out to evaluate the controller performance against some recent strategies proposed in the specialized literature