Effect of tofu wastewater concentration on lipid content of

Chlorella vulgaris has emerged as a promising microalgal species for alternative energy development due to its ability to accumulate lipids ranging from 5% to 40% of its dry biomass. In this study, tofu wastewater was employed as a cultivation medium, given its rich content of essential nutrients including nitrogen, phosphate (P₂O₅), potassium (K₂O), and organic carbon, which are critical for supporting microalgal growth. Beyond nutrient composition, light wavelength is also recognized as a key factor influencing photosynthetic energy absorption, thereby affecting both growth performance and lipid productivity. The objective of this research was to identify the optimal concentration of tofu wastewater and light wavelength for maximizing the growth and lipid content of Chlorella vulgaris. Cultivation experiments were conducted over a 10-day period using tofu wastewater concentrations of 0%, 10%, 15%, and 20%. Biomass growth was evaluated via gravimetric dry weight analysis, and lipid accumulation was quantified using the Bligh–Dyer method. Results indicated that a 15% tofu wastewater concentration yielded the highest biomass (2.054 g/L), with a specific growth rate of 0.354 day⁻¹ and a lipid content of 10.23%, suggesting that moderate nutrient enrichment supports optimal microalgal productivity.