Heterotrophic cultivation of microalgae using aquaculture wastewater: A biorefinery concept for biomass production and nutrient remediation

Cultivation of microalgae utilizing wastewater substrate could form a sustainable biorefinery with double benefit of biomass generation and nutrient remediation. In this study potential of aquaculture wastewater is evaluated for cultivation of Chlorella sorokiniana in heterotrophic mode for generation of high value biomass. Nutrient removal potential is also assessed. Aquaculture wastewater with 400 mgL⁻¹ sodium nitrate supplementation resulted in biomass productivity of 498.14 mgL⁻¹d⁻¹. The biomass generated showed lipid productivity of 150.19 mgL⁻¹d⁻¹, carbohydrate productivity of 172.91 mgL⁻¹d⁻¹ and protein productivity of 141.57 mgL⁻¹d⁻¹. The nutrient removal efficiencies were 75.56% for ammonium, 84.51% for nitrates, 73.35% for phosphates and 71.88% for COD (chemical oxygen demand). The findings of this study underline the potential of aquaculture wastewater for production of valuable microalgal biomass which can be utilized for biofuels or feed application. This biorefinery concept also polished aquaculture wastewater which can be effectively reused.