INFLUENCE OF THE PROCESS PARAMETER ON CHLORELLA VULGARIS CULTIVATION FOR CO2 SEQUESTRATION AND PROTEIN PRODUCTION

Abstract

Microalgae, known for their high photosynthetic efficiency, offer a promising approach for CO? sequestration and the production of high-value products such as single-cell proteins (SCP). However, low CO? solubility in water and strain-specific tolerance limit CO₂ fixation efficiency. This study aimed to optimise CO? fixation and SCP production in freshwater Chlorella vulgaris using the Taguchi Orthogonal Array method. Key parameters, namely light (5-15 kLx), CO? concentration (1–5%), and nitrogen content (0–1 g/L), were investigated in a 2-L Schott glass bottle. Process validation was performed within the same system, and a comparative assessment was subsequently conducted against a 2-L flat-panel photobioreactor (FPPBR) to determine any differences in cultivation performance. Results showed that biomass productivity had a greater influence on CO? fixation (9.049%) and protein yield (45.78%) than CO? concentration or nitrogen content. Notably, the flat-panel PBR achieved superior growth performance (47.67%), highlighting the importance of reactor design. Logistic growth modelling with the Taguchi growth rate equation provided the best fit for the experimental data (R² between 0.6-0.93). These findings provide valuable insights for enhancing microalgae CO? capture and SCP production, although further refinement of cultivation systems and kinetic models is necessary.