Intelligent PI controller for microalgae growth in a closed photobioreactor

Abstract

One of the microorganisms used in the industry to generate high value products is the microalga. Due to its nonlinear dynamics and variation in time, bioprocesses that involve the use of microalgae pose challenges in modeling, controlling, and increasing their production. Normally, at the laboratory level, closed cultures of microalgae are carried out in photobioreactors. To produce biomass, the culture conditions can be controlled using a photobioreactor. This paper describes the design of an intelligent Proportional-Integral controller applied in a continuous culture of Chlorella vulgaris microalga, where the controlled variable is the dilution rate D(t). This controller is characterized by formulating the dynamics of the system with an ultra-local model. In this ultralocal model, both the uncertainties of the system dynamics and the disturbances are handled in one unified way. The performance of the intelligent Proportional-Integral controller was tested at simulation level using Matlab EnvironmentTM. In this research, the accomplishment of the controller was contemplated against disturbances, under nominal conditions and front variation of parameters. The simulations showed that the intelligent Proportional-Integral controller ensures excellent reference tracking capability. Finally, it is important to highlight the robustness of the strategy.