Improvement of microalgae cultivation process through modeling and optimization

Abstract

The third generation biomass microalgae has been received huge attention due to its non-competitiveness with food crop as well as overwhelming productivity compared to other first- and second-generation biomass. However, at present, the fuel production from microalgae has not cost competitive since there are a number of technical barriers that need to be overcome for its commercialization. In the current study, process systems engineering approaches including modeling and optimization are implemented in order to enhance the economic feasibility of the microalgal biorefinery. Cultivation process is mainly addressed in this research since it has a large portion of the biofuel production cost from microalgae. In order to use process systems engineering approaches for enhancing microalgae cultivation process, a mathematical model for microalgal behavior is developed first. The proposed model for autotrophic (Chapter 2) and heterotrophic (Chapter 4) models are developed based on a central metabolic pathway of microalgal growth and macromolecules syntheses. Along with pathway-based model structure, two different cell growth behaviors (hyperplasia and hypertrophy) are considered for establishing the model. Based on the proposed model, a performance comparison of operation strategies after their operating conditions are optimized using the previously developed model for culturing microalgae (Chapter 3). Lipid productivity is optimized, and related capital expenditures are also analyzed. In the last part, possible applications using the proposed works are introduced (Chapter 5) with the preliminary results.