The cultivation of Anabaena variabilis in a bubble column operating under bubbly and slug flows

► Two different bubble shapes can be obtained in a bubble column photobioreactor: bubbly and slug flows. ► The growth rate of cells in the slug flow was larger than that in the bubbly flow in the deceleration phase. ► The maximum cell concentration in the slug flow was larger than that in the bubbly flow. ► The bubble shape in the slug flow was advantageous in regards to the radial circulation of cells.