Selection of photosynthetic microorganisms grown in artificial saline industrial effluents with liquid digestate: From screening to consortium cultures

The objective of this study was to determine the feasibility of using saline industrial streams as a culture medium to grow microalgae and cyanobacteria. Experiments were performed to determine the extent of the growth in artificial saline produced water and aquifer water supplemented with liquid digestate. Tests were performed in 96-wells microplates. Media were composed with different proportion of saline artificial produced water or aquifer water supplemented with 5% v/v liquid digestate (final concentrations: 149–195 mgN·L−1, 1.5–2.7 mgP·L−1). Media were completed to 100 % with artificial seawater, corresponding to final salinities of 40, 70 and 100 g·L−1. D. salina, N. oceanica and T. suecica showed the best growth rates. They were selected to perform mixed cultures in 80 mL tubes in the same culture media. Population evolutions were followed for 19 days. Depending on salinity and industrial effluent used, different species became predominant over the two others (N. oceanica, T. suecica and D. salina. at 40, 70 and 100 g·L−1, respectively). It appears that mixed culture is a good solution to have a biomass production during a culture process where the culture media will evolve in terms of salinity and composition.