2.2.5 Commercial Applications of Horizontal Tubular PBRs
Currently, many biotech companies around the world are using tubular photobioreactors to produce microalgae biomass and several bioproducts. Among them
are the Algaelink in the Netherlands that use horizontal and tubular photobioreactors for biomass and jet fuel production. The Heliae (USA) is using spiral tubular
PBR to produce astaxanthin from H. pluvialis. In Cadiz, Spain, the Fitoplancton
Marino SL uses a horizontal serpentine PBR cooled by immersion in a water pool
to produce lyophilized microalgae biomass and slurries of several microalgae for
aquaculture use (Torzillo et al. 2015; Chang et al. 2017).
2.3 Microalgal Heterotrophic Bioreactors
The heterotrophic bioreactors are a feasible alternative to overcome the light energy
dependency that limits the scale-up and significantly complicates the design of
photobioreactors (Vieira et al. 2012). Although restricted to a few microalgal
species, the heterotrophic cultivation can be conducted in conventional reactor
configurations such as stirred tank and bubble column reactors, which are relatively
cheap, easily scalable, and generally present high kinetic performance (Queiroz
et al. 2011; Perez-Garcia et al. 2011).
Moreover, to reduce the cost related to microalgae biofuel production, the
organic carbon source and nutrients for the microalgae cultivation can be obtained
from agro-industrial wastes (Queiroz et al. 2011; Francisco et al. 2015; Katiyar
et al. 2017). In addition to meeting the demand for organic carbon, the use of
wastewater in these cultivations also contributes to agro-industrial waste management (Maroneze et al. 2014).
On the other hand, the major limitations of these types of cultivation are the
contamination and competition with other microorganisms that grow faster than the
microalgae, inability to produce light-induced metabolites and inhibition of growth
by excess organic substrate.
2.3.1 Major Factors Affecting Bioreactors in Heterotrophic
Cultivations
Oxygen Supply
In aerobic bioprocesses, oxygen is a critical substrate for a cell metabolism that
needs continuous supply, as it can easily become rate limiting due to its low
solubility in water. According to Griffiths et al. (1960), independent of the organic
substrate or the microalgae species, the biomass productivity is enhanced by higher
levels of aeration.
2 Microalgal Production Systems with Highlights …
15
Currently, many biotech companies around the world are using tubular photobioreactors to produce microalgae biomass and several bioproducts. Among them
are the Algaelink in the Netherlands that use horizontal and tubular photobioreactors for biomass and jet fuel production. The Heliae (USA) is using spiral tubular
PBR to produce astaxanthin from H. pluvialis. In Cadiz, Spain, the Fitoplancton
Marino SL uses a horizontal serpentine PBR cooled by immersion in a water pool
to produce lyophilized microalgae biomass and slurries of several microalgae for
aquaculture use (Torzillo et al. 2015; Chang et al. 2017).
2.3 Microalgal Heterotrophic Bioreactors
The heterotrophic bioreactors are a feasible alternative to overcome the light energy
dependency that limits the scale-up and significantly complicates the design of
photobioreactors (Vieira et al. 2012). Although restricted to a few microalgal
species, the heterotrophic cultivation can be conducted in conventional reactor
configurations such as stirred tank and bubble column reactors, which are relatively
cheap, easily scalable, and generally present high kinetic performance (Queiroz
et al. 2011; Perez-Garcia et al. 2011).
Moreover, to reduce the cost related to microalgae biofuel production, the
organic carbon source and nutrients for the microalgae cultivation can be obtained
from agro-industrial wastes (Queiroz et al. 2011; Francisco et al. 2015; Katiyar
et al. 2017). In addition to meeting the demand for organic carbon, the use of
wastewater in these cultivations also contributes to agro-industrial waste management (Maroneze et al. 2014).
On the other hand, the major limitations of these types of cultivation are the
contamination and competition with other microorganisms that grow faster than the
microalgae, inability to produce light-induced metabolites and inhibition of growth
by excess organic substrate.
2.3.1 Major Factors Affecting Bioreactors in Heterotrophic
Cultivations
Oxygen Supply
In aerobic bioprocesses, oxygen is a critical substrate for a cell metabolism that
needs continuous supply, as it can easily become rate limiting due to its low
solubility in water. According to Griffiths et al. (1960), independent of the organic
substrate or the microalgae species, the biomass productivity is enhanced by higher
levels of aeration.
2 Microalgal Production Systems with Highlights …
15