Figure 2: ( A) Optical density (684 nm, natural logarithm; empty squares) and cell density (natural logarithm;full squares); (B) clorophylla (natural logarithm, full circles) and pH (empty circles) during Chlorellas orokiniana growth in the 200 L hybrid photobioreactor. Continuous system was used up to day 5; arrowindicates exchange of 30 L used media with stressing medium (extra copper added).