66 Marine Macro- and Microalgae: An Overview
To prevent this, a constant selection pressure is necessary by the addition of antibiotics (a potential
public health hazard).
Nutrients
Microalgae require inorganic nutrients (P, N, and C), sufficient light, and favorable temperatures to grow.
Hydrogen (H) and oxygen (O) are also essential for algal growth, but water (H 2 O) provides an abundance
of these elements and no further discussion of H and O is necessary to algal nutrient requirements.
Many other elements are needed for algal growth in trace amounts; they are collectively referred as
micronutrients (calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), iron (Fe), manganese (Mn),
sulfur (S), zinc (Zn), copper (Cu), and cobalt (Co)). It is also important to understand that different algal
species do not have identical nutritional needs (Grobbelaar 2013).
Biomass production
Algal biomass can be a source of fine chemical, proteins, pharma products, poultry feeds, feed stock and a
variety of biofuels (e.g., biodiesel, hydrogen, methane, and bioethanol). Furthermore, it is being seriously
considered for the removal of carbon dioxide from the flue gases (e.g., petroleum power stations). Thus
it reduces global warming considerably.
Photobioreactor
Basically, photobioreactors (PBRs) have different types of tanks in which algae are cultivated (Richmond
2004). PBRs are closed cultivation systems to grow microalgae under photo-autotrophic conditions.
Several types of PBRs have been experimented on since 1950s, when algal cultures were first considered
the ideal solar technology to produce as a cost-effective biomass and protein on a large scale. Algal
cultures consist of a single or several specific strains optimized for producing biomass as a product. Ideal
growth conditions for microalgal cultures are strain specific, and the biomass productivity depends upon
many factors. These include abiotic factors like temperature, pH, water quality, minerals, carbon dioxide,
light cycle, and intensity. Water, nutrients, and CO 2 are provided in a controlled way, while oxygen has
to be removed. Biotic factors like cell fragility and cell density, mechanical factors include mixing, gas
bubble size and distribution, and mass transfer are of particular concern in photobioreactors (Schenk et al.
2008). Growth of heterotrophic algae in conventional fermentors is preferred instead of photobioreactors
for production of high-value products (Jiang and Chen 1999; Wen and Chen 2003), since instead of light
and photosynthesis, heterotrophic algae rely on carbon sources in the medium (Ward and Singh 2005).
Photobioreactors classified on the basis of both design and operation. The most used designs are
flat-plates, tubular reactors, air-bubbled plastic bags. Some of them are artificially illuminated with
fluorescent. But the recommended two types of PBRs are flat and tubular reactors (Tredici et al. 2010).
Generally, PBRs are more expensive to install and operate, intensive study is still going on to reduce their
cost and thus facilitate their use especially for low value products like algal oils. All parameters (nutrients,
light regime, gas exchange) are maintained to realize optimal culture conditions. The contamination level
is much lower compared to open systems. Engineering PBR is still a very active field of research, since
closed culture systems are necessary to grow typical photosynthetic microbes and exploit them as a source
of aquaculture feeds, food additives, fine chemicals, pharmaceuticals, cosmetics are preferred by industry
as research tools for biofuel production. The operation costs are normally significantly higher than those
of ponds (Chisti 2007; Tredici et al. 2010). Besides, there is the need for cooling, which is generally
provided by water (even seawater) spraying or by insertion of a cooling serpentine in the culture.
Open raceway pond
Open pond systems are shallow ponds (a maximum of 50 cm) in which algae are cultivated. Nutrients
can be provided by mixing with few liters of water nearby paddle wheels. The water is typically kept
To prevent this, a constant selection pressure is necessary by the addition of antibiotics (a potential
public health hazard).
Nutrients
Microalgae require inorganic nutrients (P, N, and C), sufficient light, and favorable temperatures to grow.
Hydrogen (H) and oxygen (O) are also essential for algal growth, but water (H 2 O) provides an abundance
of these elements and no further discussion of H and O is necessary to algal nutrient requirements.
Many other elements are needed for algal growth in trace amounts; they are collectively referred as
micronutrients (calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), iron (Fe), manganese (Mn),
sulfur (S), zinc (Zn), copper (Cu), and cobalt (Co)). It is also important to understand that different algal
species do not have identical nutritional needs (Grobbelaar 2013).
Biomass production
Algal biomass can be a source of fine chemical, proteins, pharma products, poultry feeds, feed stock and a
variety of biofuels (e.g., biodiesel, hydrogen, methane, and bioethanol). Furthermore, it is being seriously
considered for the removal of carbon dioxide from the flue gases (e.g., petroleum power stations). Thus
it reduces global warming considerably.
Photobioreactor
Basically, photobioreactors (PBRs) have different types of tanks in which algae are cultivated (Richmond
2004). PBRs are closed cultivation systems to grow microalgae under photo-autotrophic conditions.
Several types of PBRs have been experimented on since 1950s, when algal cultures were first considered
the ideal solar technology to produce as a cost-effective biomass and protein on a large scale. Algal
cultures consist of a single or several specific strains optimized for producing biomass as a product. Ideal
growth conditions for microalgal cultures are strain specific, and the biomass productivity depends upon
many factors. These include abiotic factors like temperature, pH, water quality, minerals, carbon dioxide,
light cycle, and intensity. Water, nutrients, and CO 2 are provided in a controlled way, while oxygen has
to be removed. Biotic factors like cell fragility and cell density, mechanical factors include mixing, gas
bubble size and distribution, and mass transfer are of particular concern in photobioreactors (Schenk et al.
2008). Growth of heterotrophic algae in conventional fermentors is preferred instead of photobioreactors
for production of high-value products (Jiang and Chen 1999; Wen and Chen 2003), since instead of light
and photosynthesis, heterotrophic algae rely on carbon sources in the medium (Ward and Singh 2005).
Photobioreactors classified on the basis of both design and operation. The most used designs are
flat-plates, tubular reactors, air-bubbled plastic bags. Some of them are artificially illuminated with
fluorescent. But the recommended two types of PBRs are flat and tubular reactors (Tredici et al. 2010).
Generally, PBRs are more expensive to install and operate, intensive study is still going on to reduce their
cost and thus facilitate their use especially for low value products like algal oils. All parameters (nutrients,
light regime, gas exchange) are maintained to realize optimal culture conditions. The contamination level
is much lower compared to open systems. Engineering PBR is still a very active field of research, since
closed culture systems are necessary to grow typical photosynthetic microbes and exploit them as a source
of aquaculture feeds, food additives, fine chemicals, pharmaceuticals, cosmetics are preferred by industry
as research tools for biofuel production. The operation costs are normally significantly higher than those
of ponds (Chisti 2007; Tredici et al. 2010). Besides, there is the need for cooling, which is generally
provided by water (even seawater) spraying or by insertion of a cooling serpentine in the culture.
Open raceway pond
Open pond systems are shallow ponds (a maximum of 50 cm) in which algae are cultivated. Nutrients
can be provided by mixing with few liters of water nearby paddle wheels. The water is typically kept