Optimizing biomass and metabolite recovery from municipal wastewater using locally isolated microalgae strains

Municipal wastewater is rich in essential nutrients required for microalgae growth, making it a promising alternative for cultivating microalgae biomass and producing valuable metabolic compounds. This study investigated the simultaneous biomass production and nutrient removals from municipal wastewater using two locally isolated microalgae strains, Desmodesmus armatus MO1 and Tetradesmus obliquus MO2. After eight days of cultivation, nitrogen and phosphorus removal reached 96% and 60%, respectively. Biomass production was recorded at 1.375 g/L which exceeded the productivity obtained in the positive control using AF-6 media. Metabolic compound analysis revealed increased production of carbohydrates and lipids when wastewater was used as the cultivation medium, The highest carbohydrate content, 49%, was observed in Tetradesmus obliquus MO2, while Desmodesmus armatus MO1 produced the highest lipid yield at 0.214 g/L in wastewater. The study also highlighted increased production of omega fatty acids (omega-3, omega-6, and omega-9) in both species by cultivation in wastewater samples. These included the production of oleic acid (C18:1), linoleic acid (C18:2), arachidonic acid (C20:4) and docosahexanoic acid (C22:6). Major fatty acid was found to be oleic acid (C18:1), noted at 20% in Desmodesmus armatus MO1 and 51% in Tetradesmus obliquus MO2. These findings suggest that biomass from locally isolated microalgae strains cultivated in municipal wastewater holds significant potential for various applications.