초록
Chlorella protothecoides, a lipid-producing microalga, was grown heterotrophically and autotrophically in separate reactors, the off-gases exiting the former being used to aerate the latter. Autotrophic biomass productivity with the two-reactor association, 0.0249gL<SUP>-1</SUP>h<SUP>-1</SUP>, was 2.2-fold the value obtained in a control autotrophic culture, aerated with ambient air. Fatty acid productivity was 1.7-fold the control value. C. protothecoides heterotrophic biomass productivity was 0.229gL<SUP>-1</SUP>h<SUP>-1</SUP>. This biomass' fatty acid content was 34.5% (w/w) with a profile suitable for biodiesel production, according to European Standards. The carbon dioxide fixed by the autotrophic biomass was 45mgCO<SUB>2</SUB>L<SUP>-1</SUP>h<SUP>-1</SUP> in the symbiotic arrangement, 2.1 times the control reactor value. The avoided CO<SUB>2</SUB> atmospheric emission represented 30% of the CO<SUB>2</SUB> produced in the heterotrophic stage, while the released O<SUB>2</SUB> represented 49% of the oxygen demand in that stage. Thus, an increased efficiency in the glucose carbon source use and a higher environmental sustainability were achieved in microalgal biodiesel production using the proposed assembly.