Method for producing biomass and photobioreactor for cultivating phototrophic or mixotrophic organisms or cells

According to the proposed method for producing biomass, the organisms or cells are cultivated in a suspension kept in circulation in a photobioreactor, wherein light is supplied and at least CO is supplied as a nutrient. In order to cultivate the organisms or cells, the suspension is discharged by means of at least one discharge element in an upper area of a culture chamber and the downward motion of the suspension is decelerated by means of at least one interior element arranged in the culture chamber, which interior element has a horizontally extending grille, sieve, or net structure. The suspension is transformed into a plurality of drops on this structure. The drops undergo a drop cycle, by means of which the downward motion of the suspension is decelerated and an especially intensive exposure of the organisms or cells contained in the nutrient solution to the nutrients and light introduced into the reactor is guaranteed.