Screening microalgae strains for their productivity in methane following anaerobic digestion

Interest in the use of microalgae for the production of biofuels has grown in recent years. Biomethane is a biofuel that can be obtained with high efficiency from anaerobic digestion of various organic feedstocks. In this study, a selection of freshwater (n = 15) and marine (n = 5) microalgae were tested in order to identify a microalgal strain that could be used as a model for large scale production of methane. Analysis of pH, volatile suspended solids and ammonium at the end of the assay ranged between 6.98\u20137.66, 16.0\u201325.9 g/L and 495\u20131622 mg/L respectively. No significant differences in these values were detected between freshwater and marine strains. There was no significant difference in the methane yield from freshwater microalgae (329 \ub1 43 mL CH4/g TVS) and marine microalgae (298 \ub1 83 mL CH4/g TVS) although it varied greatly within the tested strains. A statistical analysis of the microalgae grown under two different culture media showed that the type of medium was more determinant than the type of microalgae (freshwater or marine) for the methane yield, with 310 \ub1 35, 365 \ub1 25 and 303 \ub1 77 mL CH4/g TVS for the freshwater microalgae grown in Bold\u2019s-3NV, f/2 and marine microalgae grown in f/2 media, respectively. The strains Scenedesmus sp.-AMDD, Isochrysis sp. and Scenedesmus dimorphus displayed the best methane yield with 410 \ub1 6, 408 \ub1 4 and 397 \ub1 10 mL CH4/g TVS, respectively. The strain Scenedesmus sp.-AMDD was chosen as a model strain for future work development with continuously fed digesters.Peer reviewed: YesNRC publication: Ye