Biomedical Engineering Reference
In-Depth Information
Extracts from microalgae are creating a new sector for microalgal products (Pulz
and Gross, 2004). Products made from algal extracts include
Chlorella
health drinks
and
Spirulina
liquid CO
2
extracted antioxidant capsules. The microalgal biomass
from
Spirulina
and
Chlorella
is not only used in human nutrition, but also in animal
feed (Pulz and Gross, 2004), as it has been proven to support the immune system
of animals. The market value of
Spirulina
and
Chlorella
is estimated at US$80 and
$100 million, respectively (Radmer, 1996).
10.2.4.4 Biofertilizers
Algal biomass is the main product in microalgal technology and has various applica-
tions. The final biomass product is usually green or orange in color (Pulz and Gross,
2004). Most commercial fertilizers are derived from petroleum; however, rising fuel
prices influence the cost price of commercial fertilizers derived from petroleum.
A cost-effective alternative would be the use of algal biomass as organic fertilizers
(http://www.algaewheel.com).
Microalgae have been used in the agriculture industry as biofertilizers and as
soil conditioners (Metting, 1996). Employing microalgae as biofertilizers and soil
conditioners is a common agricultural practice in Asian countries such as China
and India, where they provide more than 20 kg nitrogen ha
−1
y
−1
. Nitrogen-fixing
cyanobacteria such as
Anabaena, Nostoc, Aulosira Tolypothrix,
and
Scytonema
are
used in rice cultivation. Mucilage-producing species of the genus
Chlamydomonas
have been used as soil conditioners to control soil erosion of pivot-irrigated soils
in North America (Metting, 1996). The rationale behind using microalgae as
biofertilizers is that they have the ability to increase the water-binding capacity
and mineral composition of the soil (Pulz and Gross, 2004). This market generates
a turnover of US$5 billion y
−1
(Pulz and Gross, 2004).
10.2.4.5 Bioremediation/Phycoremediation
The use of microalgae for municipal wastewater treatment has been a focus of
research and development for decades as they have the ability to metabolize sewage
more rapidly than bacterial treatments (Olguín, 2003). Through photosynthesis,
algae assimilate nitrates, phosphates, and other nutrients present in the wastewater
(http://www.algaewheel.com). In addition, the oxygen given off by algae is the pri-
mary contribution toward the treatment of municipal wastewaters and industrial
effluents (Metting, 1996). Wastewater treatment systems that rely on microalgae for
oxygen production are dominated by chlorophytes (Metting, 1996).
Additionally, biomass from high-rate algal pond (HRAP) systems (such as animal
wastewater and fish farm wastewater) can be harvested for use as animal feed; a con-
cept that has been demonstrated by Lincoln and Earle (1990) and Metting (1996), as
part of an integrated recycling system (IRS) (Olguin, 2003). Such a system would
incorporate animal waste as an input and several by-products and high-value-added
products (algae) as overall outputs. “Bioespirulinema,” a system carried out by Olguín
(2003), has been operating effectively, and with a 4-year average
Spirulina
produc-
tivity of 39.8 tonnes ha
−1
y
−1
. The average protein content of the ash-free
Spirulina
biomass was 48.39% dry weight; which is relatively high for a system where there
are no nitrogen costs.
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