Droop model identification via model-based design of experiments to describe microalgae nitrogen uptake in continuous photobioreactors

Abstract

The comprehension of nutrients uptake and exploitation dynamics is a key aspect to increase the efficiency and the environmental sustainability of microalgal production at industrial scale. The Droop model is suitable for the description of the effect of nutrients on microalgal growth, but presents challenges in parameter identification due to the high correlation between parameters and the significant experimental effort required.Model-based design of experiments is employed to plan information-rich experiments for precise parameters estimation, based on dynamic variations of dilution rate and nitrogen concentration in a continuous photobioreactor growing microalga Tetradesmus obliquus. It is shown that only two optimal experiments of 8 days each are sufficient to attain a statistically satisfactory estimation of all model parameters, thus minimising time and resources. Validation experiments show that the model can capture nitrogen uptake dynamics effectively, and demonstrate that the design of optimal dynamic experiments allows calibrating the Droop model rapidly, making it a valuable tool for the study of nutrients dynamics in continuous microalgal cultivation systems.