Synergistic nutrient removal by native microalgae-bacteria consortium: key parameter evaluation

Nutrient bioremediation processes in wastewater are becoming a prevalent focus of research, with microalgae emerging as prominent players. Such microorganisms provide a compelling alternative to traditional sanitation approaches. In light of this emerging interest, the main objective of this study was to explore diverse growth conditions of a native microalgae-bacteria consortium in domestic wastewater, aiming at nutrient bioremediation and biomass production. The investigation was performed on a laboratory scale through Schott® 2.0 L glass bottle photobioreactors, utilizing anaerobically digested wastewater to mitigate its polluting potential effectively. At first, the impact of increasing inflow of CO2 was evaluated. It was found that the addition of 5% CO2 yielded the most favorable outcomes, with the remarkable 96.5% of total phosphorus removal within four days alongside a biomass production rate of 0.04 g.L-1.d-1. In later steps, variations in light intensity were analyzed, and with 304±3 μmol.m-2.s-1, yielded the most promising results, with total phosphorus removal of 97.1% within two days and biomass production rate of 0.31 g.L-1.d-1. Finally, the influence of temperature was assessed, uncovering 97.2% total phosphorus removal within two days, complemented by a biomass production rate of 0.29 g.L-1.d-1. These results facilitated the development of a surface model illustrating the intricate relationship between light and temperature for this consortium. Furthermore, the consortium exhibited remarkable proficiency in nutrient removal from anaerobically digested wastewater, showcasing noteworthy resilience to temperature and light intensity fluctuations.