Abstract
The efficient growth of microalgae in sewage wastewater presents a sustainable approach for the recovery of valuable products, such as lipids and hydrocarbons. This study focuses on bench-scale cultivation and optimization to enhance the growth rates and biomass productivity of Scenedesmus sp., Chlorella vulgaris, and Spirulina platensis. The performance of bench-scale reactors under controlled conditions was investigated to maximize algal growth and biomass productivity. The objective of this study employed a series of bench-scale experiments populated using Box-Behnken in Design Expert, Design of Experiments (DOE) to identify optimal configurations. Key parameters, including pH (6.5 – 10), illumination period of light: dark (0:24, 6:18, 12:12. 18:6, 24:0), and growth medium to wastewater ratio of (0:4, 1:3, 2:2, 3:1, 4:0) were systematically varied to assess their effects on microalgal growth. The results demonstrated that specific conditions significantly influenced algal growth and overall lipid productivity. Using Bold’s Basal Medium (BBM) for cultivation, Scenedesmus sp. achieved the highest growth rate of 0.86/d with biomass productivity of 39 × 104 cells/mL/d. Chlorella vulgaris performed best with a growth rate of 0.434/d and 24.38 × 104 cells/mL/d. Spirulina platensis maximum growth rate achieved 0.268/d and 23.36 × 104 cells/mL/d. Bench scale experiments further identified and incorporated optimal cultivation conditions, achieving higher growth rates and biomass productivity. These findings demonstrated the potential of optimized bench-scale reactors, providing a scalable solution for biofuel production using bubble columns, airlift reactors and industrial applications. This research contributes to the development of sustainable biofuel production technologies aligning with global efforts to reduce environmental impact and promote renewable energy sources.
