Optimal input design for sensitivity analysis of microalgal bioreactor systems

Microalgae are photosynthetic microorganisms with an ability to produce large amounts of oil that can be used directly as a high value bioactives or be used to synthesize biodiesel. In this study, a first principles ODE model for microalgae growth and neutral lipid synthesis proposed by Surisetty et al. (2010) is investigated for the purpose of maximizing the rate of microalgae growth and the amount of neutral lipid. The model has 6 states and 12 parameters and follows the assumption of Droop model which explains the growth as a two-step phenomenon; the uptake of nutrients is first occurred in the cell, and then use of intracellular nutrient to support cells growth. In this study, optimal input design (OED) using D-optimality criterion is performed to compute the optimal input profile which have a maximum information for the sensitivity analysis. Then, sensitivity anlaysis is performed to determine which parameters have a negligible effect on the model predictions.