Optimization of Phaeodactylum tricornutum cultivation for enhancing mariculture wastewater treatment and high value product recovery using Box–Behnken design

Abstract

The use of microalgae for mariculture wastewater (MW) treatment enables the simultaneous purification of wastewater and high value product recovery. In this study, Phaeodactylum tricornutum (P. tricornutum) was cultivated in MW, and Response surface methodology (RSM) was employed to optimize operational parameters of light intensity, illumination time, and temperature, aiming to maximize biomass production and pollutant removal. Light intensity and illumination time were significant factors affecting microalgal growth, while all three factors played a vital role in lipid production. However, only illumination time had a significant effect on the removal efficiencies of COD and NH₄⁺-N. The optimum conditions for the cultivation of P. tricornutum in MW were 4000 lux light intensity, 12 hours of illumination per day, and a temperature of 20°C. Under optimal conditions, the carbohydrate, protein and lipid content reached 43.3, 305.2 and 814.3 mg/L with COD, NH₄⁺-N and TP removal of 70 %, 96 % and 90 %, respectively. Regression coefficients were calculated to validate the accuracy of the quadratic polynomial model in predicting key response variables. Analysis of variance (ANOVA) showed that the coefficients of determination (R²) for all response variables were above 0.98, indicating strong agreement between the predicted values and experimental data. These findings provide valuable insights for optimizing microalgae-based treatments and demonstrate the potential of P. tricornutum for both biomass accumulation and pollutant removal in MW.