Harnessing dairy wastewater to cultivate Scenedesmus sp. for biofertilizer applications in Phaseolus vulgaris L.: a sustainable agro-biotechnological approach

Transforming traditional linear production into sustainable circular processes is crucial, and integrating microalgae biomass production with wastewater recycling is a promising approach. This study addresses key challenges using dairy industry effluents as a nutrient-rich medium, achieving high biomass productivity and protein content with <i>Scenedesmus</i> sp. grown in an 80% wastewater-based medium. Impressive nutrient removal efficiencies were recorded for TN (79.24%) and PO₄ ^-3 (77.14%). The proposed culture medium achieved maximum productivity of 0.22 ± 0.05 g L^-1 day^-1 and a high protein concentration of 384.38 ± 34.06 mg g^-1, demonstrating the medium's efficiency in promoting substantial biomass and nutritional quality. The application of <i>Scenedesmus</i> sp. biomass in treatment T₁ (extract) and T₂ (culture) in <i>Phaseolus vulgaris</i> significantly improved soil quality, increasing the concentration of organic matter (SOM), nitrates, phosphates, and microbial activity. Additionally, T₁ promoted the vegetative and reproductive development of <i>P. vulgaris</i>, as reflected in a germination index of 305.81%, an average height of 49.52 cm, higher leaf density, a greater number of floral buds, and enhanced floral development. These results demonstrate the bio-stimulatory potential of biomass and its role in practical bioremediation, highlighting the environmental and agricultural benefits of this innovative approach.