The effect of photoperiod and aerator type on lipid production and CO₂ capture efficiency in the cultivation of Chlorella vulgaris

¹ Bioprocess Engineering Study Program, Faculty of Biotechnology, Institut Teknologi Del, North Sumatra, Indonesia
² PT Aimtopindo Nuansa Kimia, Kawasan Industri De Prima Terra, Jalan Raya Sapan Tegalluar, Bojongsoang, Kabupaten Bandung, West Java

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

The increase in carbon dioxide (CO₂) emissions to 36.8 billion tons in 2023 prompted innovative research into mitigating climate change. This research focused on optimizing the environmental conditions of Chlorella vulgaris, which acted as a carbon capture and storage (CCS) agent in lipid production. In this study, a photobioreactor culture of Chlorella vulgaris was used with variations in light-to-dark photoperiods (12:12, 16:8, and 24:0) and aerator types (nanodisc, stick aerator, and ball aerator). The photoperiod variations were used to determine the maximum growth rate, while the aerator type variations were used to identify the maximum kLa value (gas volumetric mass transfer coefficient). The two variations with the highest results were combined to analyze lipid yield. The cultivation process used distilled water and NPK medium at a concentration of 1 g/L. Microalgae harvesting was performed using sedimentation-gravity and diffusion methods, while lipid extraction was conducted using the Soxhlet method followed by distillation. Based on the study, the 24:0 photoperiod variation yielded the maximum growth rate of 0.6575 gram/L/day, and the nanodisc aerator type variation produced the maximum kLa value of 0.0191/minute. From the cultivation of Chlorella vulgaris with a volume of 160 L, a photoperiod of 24:0, using a nanodisc aerator, and injected with 0.104 LPM of CO₂, lipid yield reached 58.25% and CO₂ absorption was 15.38% of the total CO₂ provided. From this results it appears that the optimal combination of aerator and photoperiod can increase lipid production and also support the role of microalgae as biological carbon capture and storage.