A hybrid MRAC-PI approach to regulate pH in raceway reactors for microalgae production

Abstract

This study presents the design, analysis and experimental evaluation of a hybrid Model Reference Adaptive Control (MRAC) structure for pH regulation through CO${}_2$ injection in an open raceway reactor, addressing the nonlinear and time-varying dynamics of outdoor microalgae production systems. Conducted at the IFAPA center-University of Almería, the research compares the MRAC’s performance with traditional control solutions in these processes. Results indicate that the hybrid MRAC controller significantly outperforms conventional controllers, as demonstrated by performance indices. The MRAC’s ability to adapt to varying conditions was particularly noteworthy, enabling real-time adjustments and effective pH regulation. During continuous operation in real facilities for twelve days in two different months, the MRAC maintained the pH within the desired range, highlighting its robustness and suitability for industrial applications in microalgae photobioreactors. These findings contribute to the development of efficient and adaptive solutions for complex industrial processes, promoting sustainable and cost-effective microalgae production.