Outdoor cultivation of Chlorella sorokiniana in third generation biorefinery: Resource savings through medium recycling

The reduction of resource requirements for the outdoor cultivation of Chlorella sorokiniana using 180 L flat panel photobioreactors through medium recycling was investigated in this study. Without medium recycling, algae grew in 13.6 d from 0.92 to 5.32 gL-1with a productivity of 0.32 gL-1d-1. For the production of 748 g algae dry weight (DW), 152gkg-1 N, 27 gkg-1 P and 231 Lkg-1 water were needed. A realistic cultivation model with the recycling of medium and a productivity of 0.4 gL-1d-1 was set up based on experimental data, in which the requirements decreased to 104gkg-1 N, 24 gkg-1 P and 141 Lkg-1 water. Compared to the production of lutein-containing plant Tagetes erecta, water and potassium requirements of up to 91% less and 96% respectively and higher biomass productivity by the factor 3.7 was achieved. © 2020 Elsevier Ltd