Microalgae strains isolated from piggery wastewater in Ecuador: Effective nitrogen compound removal and growth potential in extremophile conditions

Effluents generated by anthropogenic activities are a significant source of pollution and eutrophication in natural water bodies. In Ecuador, the increase in pig production has exacerbated this issue due to the untreated discharge of pig effluents. This study focused on the characterization of native microalgae present in pig effluents and the evaluation of their capacity to remove nitrogenous compounds under various conditions, with the aim of identifying efficient strains for phycoremediation. Four microalgal strains were isolated and molecularly identified as Radiococcus polycoccus, Chlorolobion braunii, Micractinium sp., and Desmodesmus multivariabilis. The cultures were exposed to initial concentrations of 100 mg L^-1 N-NH₄ and 49.97 mg L^-1 N-NO₃ for 12 days to assess their cellular growth and nutrient removal rates. Growth kinetics were analyzed under conditions of 2000 mg L^-1 N-NH₄ and extreme pH levels of 3 and 10. Chlorolobion braunii demonstrated the highest productivity, achieving a removal of 67.73 % of N-NH₄ and 30.59 % of N-NO₃, and reached the highest cellular density under extreme ammonium conditions, being the only strain capable of growing at acidic pH. Conversely, Micractinium sp. exhibited the highest growth under alkaline conditions. These results highlight the promising potential of native microalgae from pig effluents for wastewater remediation and their adaptation to environmental conditions.