A Novel Approach Towards RSM-Based Optimization of LED-Illuminated Mychonastes homosphaera Culture, Emphasizing Input Energy: An Industrial Perspective of Microalgae Cultivation

The growing demand for sustainable bioprocesses highlights microalgae as a promising source of renewable feedstock. However, high energy use for artificial lighting limits the commercial viability of photobioreactor systems. This study proposes an energy-optimized framework for cultivating Mychonastes homosphaera using LED illumination. The optimization was performed using Response Surface Methodology (RSM) with a Face-Centered Central Composite Design (FCCCD) to assess the interactive effects of light intensity, duration, airflow rate, and nitrogen concentration on biomass and lipid productivity. The performance of LED wavelengths was compared for biomass, lipid productivity, and energy consumption. RSM models were statistically significant (p < 0.01), and ANOVA had a high coefficient of determination (R2) for all LEDs. Maximum biomass productivity was 512.0 ± 12.23 mg L−1 day−1 with cool-white, followed by pink (401.33 ± 10.48), blue (342.66 ± 3.53), and red (189.6 ± 1.36). Cool-white consumed the least energy (228.6 Wh day−1) to produce the maximum biomass, compared to blue (235.05 Wh day−1), pink (240.0 Wh day−1), and red (240.0 Wh day−1). Lipid content was highest under red (22.84%), followed by pink (17.39%), blue (15.82%), and cool-white (8.96%). However, lipid productivity was highest under pink (69.8 mg L−1 day−1), followed by blue (54.2 mg L−1 day−1), cool-white (45.86 mg L−1 day−1), and red (43.3 mg L−1 day−1).