<p>Hydroponics, as an adjunct to traditional agriculture, enhances crop production by providing optimal plant growth conditions but faces environmental challenges due to incomplete nutrient utilization. Cultivating microalgae in hydroponic effluent offers an efficient solution to reclaim unused nutrients. While mixotrophic microalgal cultivation is familiar, its application in treating hydroponic effluent remains underexplored, with limited insights into how varying different organic carbon levels of supplements in the hydroponic effluent impact microalgal growth, biomass composition, and nutrient removal efficiency. To bridge this gap, the present study cultivated a microalgal consortium with two different organic carbon sources, glucose (0 to 0.75% <i>w/v</i>) and glycerol (0 to 0.75% <i>v/v</i>), at varying concentrations to investigate the impact of altered carbon:nitrogen ratio on biomass productivity, nutrient utilization, and biomass composition compared to autotrophic condition. Results reveal that mixotrophic cultivation outperformed autotrophic systems in nutrient removal, biomass productivity and microalgal lipid content, with glucose and glycerol as effective organic carbon substrates. Compared to autotrophic cultivation, mixotrophic cultivation with 0.5% <i>w/v</i> glucose significantly boosted biomass productivity by ~55%, nutrient removal by 20-60% and lipid content by 44%, while culture supplemented with 0.25% _v/v glycerol achieved a 59% higher biomass productivity, along with a 26-72% increase in nutrient removal and ~70% higher lipid content. These findings indicate that mixotrophic cultivation, particularly with low-cost carbon sources like glycerol, offers a cost-effective approach for nutrient recovery from hydroponic effluent, along with producing lipid-rich microalgal biomass, offering both economic and environmental benefits. Exploring cheaper organic carbon sources could further improve process feasibility.</p>