Screening of microalgae with potential for biodiesel production and nutrient removal from treated domestic sewage

This article reports the results of the screening of microalgae capable of removing nitrogen and phosphorus while accumulating lipids in effluents from secondary domestic wastewater treatment. Twenty strains were tested for their growth capacity; the growth parameters of 13 strains were determined, and the following three strains were selected and cultivated in photobioreactors: the isolated and unknown LEM-IM 11, Botryococcus braunii and Chlorella vulgaris. The capacity of each strain to remove nitrogen and phosphorus as well its growth rate and biomass composition was determined. B. braunii LEM 14 showed the best combined results and is a good candidate for the development of a large-scale process. From the treated domestic wastewater, 79.63% of the nitrogen and phosphorus was removed after 14 days of culture at 25 °C. Biomass composition indicated an oil accumulation (36% dry weight) and high carbon uptake (144.91 mg CO 2 g biomass - 1 L−1 day−1). Fatty acid methyl ester analysis showed a predominance of palmitic (C16:0) and oleic (C18:1) acids, with considerable amounts of stearic (C18:0), linoleic (C18:2) and alpha-linolenic (C18:3) acids.