EFFECT OF CONCENTRATION OF CO2 DISSOLVED MIXOTROPHIC CULTURE OF Scenedesmus obliquus

Abstract

A mixture of autotrophic (Scenedesmus obliquus) and heterotrophic (bacterial consortium) microorganisms was cultivated in a fotobioreactor in an open outdoor solar cultivation of falling field of type Setlik with 5 cm of depth and 1,6 area m2 (Setlik et all 1970). The behavior of the mixture
of microorganisms was evaluated with 0,3 and 1% of dissolved CO2, coming from the heterotrophic oxidation of the glucose dosed to the cultivation suspension. The results of productivity and efficiency obtained are presented with both concentrations of CO2. If it is maintained in 1% the concentration of CO2
in the cultivation suspension there is a slight increase of the productivity per unit area and a considerable decrease of efficiency in the use of the glucose, caused by the increase
of the heterotrophic biomass .The opposite happened when using 0,3 % of dissolved CO2. It was also demonstrated that it is feasible to control the addition of glucose to the means measuring the CO2 dissolved in the suspension with great effectiveness.