medium is exposed to variations in weather conditions, affecting the light intensity
and temperature, besides low mass transfer, high evaporation rate, and susceptibility to contamination, which makes it unfeasible for an effective CO 2 conversion
(Razzak et al. 2017).
On the other hand, closed systems included flat-plate, bubble column, airlift,
tubular, hybrid, and biofilm photobioreactors, which enable high rates of CO 2
biotransformation in a wide variety of high-value bioproducts (Medipally et al.
2015; Tao et al. 2017). Moreover, they provide an easily controlled medium, safe
against contamination. Despite their greatest potential for commercial application,
closed systems are more expensive, due to the requirement of very transparent
material, like glass or acrylic (Vasumathi et al. 2012). Another limiting factor is that
losses of about 70% of non-bioconverted carbon are predicted when high CO 2 loads
are injected (Jacob-Lopes et al. 2009).
Given these varied configurations, currently, one of the most widely accepted
configurations for mass culture of microalgae is the closed tubular photobioreactors.
This type is basically designed to achieve a maximum surface/volume (S/V) ratio
and can be classified based on the horizontal, vertical, inclined, or helical
arrangement of the tubes. They are suitable for CO 2 conversion due to their
homogeneous mixture, greater gas transfer, smaller hydrodynamic stress,
Fig. 3 Identification of VOCs produced by Scenedesmus obliquus and released from the
photobioreactor exhaust gases. Adapted of Jacob-Lopes et al. (2017)
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and temperature, besides low mass transfer, high evaporation rate, and susceptibility to contamination, which makes it unfeasible for an effective CO 2 conversion
(Razzak et al. 2017).
On the other hand, closed systems included flat-plate, bubble column, airlift,
tubular, hybrid, and biofilm photobioreactors, which enable high rates of CO 2
biotransformation in a wide variety of high-value bioproducts (Medipally et al.
2015; Tao et al. 2017). Moreover, they provide an easily controlled medium, safe
against contamination. Despite their greatest potential for commercial application,
closed systems are more expensive, due to the requirement of very transparent
material, like glass or acrylic (Vasumathi et al. 2012). Another limiting factor is that
losses of about 70% of non-bioconverted carbon are predicted when high CO 2 loads
are injected (Jacob-Lopes et al. 2009).
Given these varied configurations, currently, one of the most widely accepted
configurations for mass culture of microalgae is the closed tubular photobioreactors.
This type is basically designed to achieve a maximum surface/volume (S/V) ratio
and can be classified based on the horizontal, vertical, inclined, or helical
arrangement of the tubes. They are suitable for CO 2 conversion due to their
homogeneous mixture, greater gas transfer, smaller hydrodynamic stress,
Fig. 3 Identification of VOCs produced by Scenedesmus obliquus and released from the
photobioreactor exhaust gases. Adapted of Jacob-Lopes et al. (2017)
13 Biofuels from Microalgae …
283