Background: Carbon dioxide (CO) is the major contributor to the
global emissions of greenhouse gases, which necessitates the search for its
fixation and utilization methods. Engaging photosynthesizing microorganisms for
its biosequestration is one of the prospective technologies applied to this end.
Considering the paucity of literature works on the possibilities of deploying
CO from biogas combustion to intensify microalgae production, this research
aimed to identify the feasibility of using this type of CO in
Chlorella vulgaris culture by evaluating biomass production yield and
CO biosequestration effectiveness. Methods: The experiment was
performed in glass PBR, in which the culture medium occupied the volume of 1.0
dm, and the gaseous phase occupied 0.3 dm. The reactors were
continuously illuminated by fluorescent lamps. The temperature of flue gases and
air fed to reactors, and culture temperature was 20 °C 2 °C.
Results: The use of flue gases promoted a more rapid biomass growth,
reaching 77.8 3.1 mgVS/dmd, and produced a higher
microalgae concentration, i.e., 780 58 mgVS/dm. Nevertheless, the
flue gas-fed culture turned out to be highly sensitive, which was manifested in a
decreased culture medium pH and relatively quickly achieved decay phase
of the C. vulgaris population. The microalgae effectively assimilated CO, reducing its concentration from 13 1%
to 1 0.5% in the effluent from the photobioreactor.
Conclusions: The flue gases were found not to affect the qualitative
composition of the microalgal biomass. However, strict control and monitoring of
microalgae biomass production is necessary, as well as rapid responses in flue
gas-fed systems. This is an important hint for potential operators of such
technological systems on the large scale. Regardless of the possibility of
deploying microalgae to fix and utilize CO, a justified avenue of research
is to look for cheap sources of CO-rich gases.