Nutrient Removal and Trade-Off Between Biomass Productivity in Monocultures and Consortium of Scenedesmus Obliquus and Chlorella Vulgaris Using Industrial Wastewater From Household Appliances

Industrial effluents from the household appliance sector present high concentrations of nitrogen and phosphorus compounds, representing an environmental challenge but also an opportunity for resource recovery through processes using microalgae. This study analyzed the nutrient removal effectiveness, kinetic parameters, and biomass productivity of Scenedesmus obliquus cultivated both in monoculture and in consortium with Chlorella vulgaris, under various configurations of industrial household appliance effluents (including raw biological effluent at dilutions of 100%, 80%, and 60%, in addition to biologically treated effluent). The experiments were conducted in a controlled laboratory environment over seven days. In monoculture, total nitrate removal (100%) was observed in all treatments, and ammonia removal reached 100% in M-RB100 and M-RB80, exceeding 80% in M-RB60. On the other hand, phosphate removal varied between 38% and 90%. Biomass productivity ranged from 0.054 to 0.153 g L⁻¹ day⁻¹, with the highest value observed in raw biological effluent diluted to 80% (M-RB80) under monoculture conditions. This resulted in a dry biomass of 1.70 g L⁻¹ and a maximum specific growth rate of 0.925 day⁻¹. The CO₂ fixation rate ranged from 0.102 to 0.287 g L⁻¹ day⁻¹, indicating photosynthetic activity. The results demonstrate the technical feasibility of incorporating microalgae cultivation into industrial wastewater treatment systems, allowing for bioremediation and biomass production simultaneously.