Sustainable Biomass Production of Euglena gracilis Cultivated in Dairy Farm Wastewater: A Growth and Lipid Yield Assessment

Dairy farming has a detrimental effect of wastewater that can pollute the environment, leading to eutrophication from increased nitrogen and phosphorus levels. Microalgae have significant potential for treating such wastewater. This study aimed to examine the influence of dairy farm wastewater concentrations on Euglena gracilis, particularly its growth, biomass, and lipid production and to develop a growth model for it. This study cultivated Euglena gracilis in Cramers & Myers (CM) medium for 18 days with wastewater concentrations of 0, 10, 25, and 50. The highest cell density, biomass, and lipid content were 64.5 x 10⁴ cells/mL, 0.560 g/L, and 0.175 g/L, respectively, in the 0 wastewater treatment. The 10 concentration yielded the best results, achieving a cell density, biomass, and lipid content of 27.0 x 10⁴ cells/mL, 0.290 g/L, and 0.127 g/L, respectively. The mathematical approach used shows that the Gompertz Model growth curve produces better simulation data than the Logistic Model. The Gompertz Model can describe Euglena gracilis cultivation with higher accuracy by accounting for the lag phase. Optimal wastewater concentration, to increase microalgae productivity, is an important aspect that can support a circular bioeconomy by using biomass as a raw material for high value products. © 2025, Gadjah Mada University. All rights reserved.