Application of selenium-enriched biomass from a microalgal consortium cultivated in domestic wastewater as a biofertilizer: effect of selenium supplementation

Microalgae offer a sustainable and versatile solution for addressing both environmental pollution and micronutrient deficiencies, such as selenium (Se) scarcity. By coupling wastewater treatment with microalgae cultivation, it is possible to recover resources with minimal energy input while producing selenium-enriched biomass suitable for high-value applications in agriculture and animal nutrition. The objective of this study was to use microalgae derived from remediating Se laden wastewaters as a potential Se-rich resource to enrich crops with Se to secure its adequate supply in Se deficient regions. The microalgae were grown on urban wastewater enriched with 500 μg/L Se (IV) and showed Se accumulation of 42.4 mg/kg biomass and an average Se(IV) removal efficiency of 48 %. The Se enriched microalgae were tested at different concentrations (0–100 mg/L) on soil for the cultivation of the Asiatic leaf vegetable pak choi. Plant growth parameters like the leaf number, root length and shoot height, fresh and dry weight were evaluated. Se-enriched biomass increased pak choi shoot and root lengths to 20 cm and 30 cm, respectively. This suggests that microalgae cultivated in the presence of wastewater containing Se can serve as a biofertilizer to enhance the growth and Se content of a plant, thus offering dual benefits of Se rich wastewater remediation and use of microalgae enriched with Se as biofertilizer for biofortification of food crops in regions that are deficient in Se. • Microalgae consortium removed 48 % of Se and stored 42.4 mg Se /kg from wastewater. • Pak Choi grown were boost with Se-microalgae reaching 30 cm roots and 20 cm shoots. • Microalgae offers dual benefits of Se rich wastewater remediation and biofortification of food crops.