Abstract
The increasing global demand for energy presents significant challenges to the availability of sustainable resources for future generations. Microalgae have emerged as a promising renewable energy source; however, further optimization of large-scale cultivation is necessary to enhance economic viability and sustainability. This study focuses on the design, fabrication, and performance evaluation of a laboratory-scale bubble column photobioreactor (PBR) for the cultivation of Chlorella vulgaris. The fabricated bubble column PBR consists of a stainless-steel frame and an acrylic column with a working volume of 32 L and a height of 75 cm. It is equipped with an 80 W air pump, LED lamps, and a three-arm spider sparger to ensure efficient gas distribution. A temperature-pH sensor and a light automation controller were integrated to maintain optimal cultivation conditions, with temperature and pH levels monitored at 25 °C-30 °C and 7-10, respectively. Nutrient concentration optimization was conducted using 14:14:14 NPK fertilizer, with the optimal concentration determined to be 40 mg/L, yielding a specific growth rate of 0.1979 cells/ml-d and a generation time of 3.50 d. Growth kinetics analysis revealed the characteristic phases of microalgal growth (lag, exponential, stationary, and death phases), with the highest biomass yield of 5.95 × 106 cells/ml observed on the fifth day of cultivation, indicating the optimal harvesting time. These findings highlight the potential of the bubble column PBR for efficient Chlorella vulgaris cultivation, demonstrating its applicability for biofuel production and other biotechnological applications.
