Autochthonous microalgae cultivation with anaerobic effluent: isolation of strains, survivorship, and characterization of the produced biomass

Abstract

Six Chlorophyta strains were isolated from the effluent of an anaerobic reactor treating municipal wastewater and identified as Desmodesmus sp. L02, Chlorococcum sp. L04, Coccomyxa sp. L05, Chlorella sp. L06, Scenedesmus sp. L08 and Tetradesmus sp. L09. The microalgae strains were cultivated in unsterilized wastewater under laboratory conditions to determine their potential to survive under non-sterile conditions. The strains were also cultivated in sterilized wastewater in order to analyze their nutrient removal potential and characterize the produced biomass. Amongst the isolated microalgae, Chlorella sp. L06 had the highest survivorship percentage (90%) for ten days of culture, whilst Desmodesmus sp. L02 had the lowest, not exceeding 1.8% after 24h of inoculation. The dried biomass of the isolates showed an average of 28.7% of protein, 15.4% of lipids and 14.8% of carbohydrates, with Chlorococcum sp. L04 reaching 29.3% of carbohydrates. In terms of nutrients, nitrogen removal varied from 59.2 to 93%, and phosphorus removal ranged from 79.1 to 95.4%, with Tetradesmus sp. L09 being the most efficient strain.