Conference on Environmental Science and Technology

Microalgae are photosynthetic microorganisms with significant potential for the sustainable production of valuable compounds, including proteins, lipids, carbohydrates, and pigments. Within the PhotoBioValue project, multiple studies were conducted to optimise Chlorella vulgaris biomass production and biochemical composition by manipulating operational conditions. In one study, the impact of light spectra (red, blue, orange, and white) was explored, revealing that red light maximised growth rates (0.509±0.004 d−1) and carbohydrate accumulation (20.2–23.5% DCW), while blue light enhanced protein content (33.8–39.0% DCW), and white light promoted NO₃-N uptake, lipid (21.6-24.5% DCW), and pigment accumulation. Another experiment examined high light intensities (291–1107 μmol m−2 s−1), demonstrating increased growth rates (0.54±0.02 d−1), nutrient removal efficiencies (>97% for NO₃-N and PO₄-P), and boosted carbohydrate (30±3% DCW) and lipid accumulation (13.0±0.4% DCW), highlighting the potential for biofuel production. To better the understanding of microalgal growth dynamics different growth kinetic models were compared, focusing on the combined impact of light intensity and biomass concentration. The Bannister and Grima models were identified as effective tools for predicting microalgal growth dynamics, aiding in optimisation. A separate study investigated salinity levels (0–600 mM NaCl), where 150 mM NaCl optimised biomass production (978±11 mg L−1) without affecting nutrient removal and 300 mM NaCl promoted lipid (24±1% DCW) and carbohydrate accumulation (32.3±0.6%). Additionally, the combined effects of light irradiance and exposure time were assessed using a solar simulator, identifying conditions that maximise biomass while preventing adverse effects. Together, these studies provided a comprehensive overview for enhancing microalgal biomass production and composition under diverse conditions. The findings have significant implications for biofuel production, bioremediation, valuable compound synthesis and the sustainable management of biomass.