applications, we believe in 2019 we are still
looking at the tip of the iceberg.
Due to the success and low prices of other
crops, many companies growing duckweed are
focused on high-tech, high-value applications to
avoid commodity markets. Similar to protein
extracts, several high-value products, like sugars,
antioxidants, and oils, are being extracted from
duckweed biomass in academic and commercial
research laboratories. Appenroth et al. conducted
a thorough investigation of W. microscopica and
found a complete plant protein, roughly 150 mg
carotenoids and 22 mg of tocopherols/gram dry
weight, and an oil profile of 61% polyunsaturated fatty acids with a high content
omega-3 s and a phytosterol content minimum
fivefold higher than common plant oils, presenting several healthy, high-value compounds
that may be extracted (Appenroth et al. 2017).
After or without extraction of certain compounds
or protein, biomass can be converted to other
products, for example MamaGrande’s research in
converting starch to sugar, and then polylactic
acid valued at *$2000 USD/ton. After enzymatically converting starch to sugar, the sugars
can be fractionated and sold, or converted to
levulinic, formic, or succinic acid (Liu et al.
2018). Pyrolysis and HTL discussed above can
be used to create bio-char, gases, and a bio-crude
oil. A subset of a single sample of duckweed
derived bio-crude oil contained over 100 distinct
compounds, mainly ketones, alcohols, fatty
acids, and cyclic compounds (Duan et al. 2013).
When considering the variables of biomass, solvents, temperature, pressure, and time HTL,
pyrolysis can be adjusted to offer countless
compounds that can be created and fractionated.
Finally, there are a variety of other high-value
application niches that duckweed can be used for
including tea, cosmetics, pet food, and aquarium
plants, which have been tested on small scale and
may develop further. Major crops such as corn
and soy have been used as feedstocks for hundreds of uses including food-thickening agents,
cosmetics, construction adhesives, and ink. It is
therefore reasonable to expect that as duckweed
abundance grows there will be a greater number
and variety of applications.
Another sector where duckweed species will
likely play an expanding role is water reclamation and supply. In 2018, the Duckweed forum
issue 22 described 23 companies in 9 countries,
with 4 each working in water quality testing and
water treatment (Shoham 2018). Provided the
perpetual rise of water pollution and increased
testing, and the roughly 50% lower capital and
operating costs of duckweed (Skillicorn 2013)
and constructed wetland (Zhang et al. 2014b)
treatment systems compared to their bacterial
counterparts, these industries are expected to
grow, likely more so in developing countries.
Sadly, 14 years of satellite observations reveal
decreasing clean water availability across the
world and in heavily populated areas like California, the Middle East, Northern India, and
Northern China where groundwater is being
depleted (Rodell et al. 2018). Many regions
suffer clean water scarcity for at least 1 month of
the year resulting in inadequate supply for people
as well as agricultural losses. Duckweed treatment systems to reclaim water, as well as water
efficient duckweed crops, with many other measures, might be utilized in these and other regions
to increase supply. Similar to water reclamation,
there is a lesser known need for phosphorous
reclamation, since our current practice is to mine
and refine phosphorous deposits, fertilize our
crops, and then let the phosphorous run directly
off of fields and into the ocean, or through our
wastewater treatment systems into the ocean
where it causes eutrophication damage like the
Gulf of Mexico hypoxic zone. Economically
mineable, organically available phosphorous is
expected to be scarce by 2050 or 2100, and
production might decline by 2030 raising its
price possibly beyond the reach of poorer farmers (Childers et al. 2011). Fortunately, phosphorous can be recycled by better farming practices
or by using more aquatic plants and other
methods to recapture more than the current rate
of 50% from human wastes. While phosphorous
is a critical macronutrient and prime example,
many other fertilizers have similar life cycles and
would follow the phosphorous in any reduce,
recapture, and reuse applications. Given the
water and fertilizer scarcities this century will
12
P. Fourounjian et al.
looking at the tip of the iceberg.
Due to the success and low prices of other
crops, many companies growing duckweed are
focused on high-tech, high-value applications to
avoid commodity markets. Similar to protein
extracts, several high-value products, like sugars,
antioxidants, and oils, are being extracted from
duckweed biomass in academic and commercial
research laboratories. Appenroth et al. conducted
a thorough investigation of W. microscopica and
found a complete plant protein, roughly 150 mg
carotenoids and 22 mg of tocopherols/gram dry
weight, and an oil profile of 61% polyunsaturated fatty acids with a high content
omega-3 s and a phytosterol content minimum
fivefold higher than common plant oils, presenting several healthy, high-value compounds
that may be extracted (Appenroth et al. 2017).
After or without extraction of certain compounds
or protein, biomass can be converted to other
products, for example MamaGrande’s research in
converting starch to sugar, and then polylactic
acid valued at *$2000 USD/ton. After enzymatically converting starch to sugar, the sugars
can be fractionated and sold, or converted to
levulinic, formic, or succinic acid (Liu et al.
2018). Pyrolysis and HTL discussed above can
be used to create bio-char, gases, and a bio-crude
oil. A subset of a single sample of duckweed
derived bio-crude oil contained over 100 distinct
compounds, mainly ketones, alcohols, fatty
acids, and cyclic compounds (Duan et al. 2013).
When considering the variables of biomass, solvents, temperature, pressure, and time HTL,
pyrolysis can be adjusted to offer countless
compounds that can be created and fractionated.
Finally, there are a variety of other high-value
application niches that duckweed can be used for
including tea, cosmetics, pet food, and aquarium
plants, which have been tested on small scale and
may develop further. Major crops such as corn
and soy have been used as feedstocks for hundreds of uses including food-thickening agents,
cosmetics, construction adhesives, and ink. It is
therefore reasonable to expect that as duckweed
abundance grows there will be a greater number
and variety of applications.
Another sector where duckweed species will
likely play an expanding role is water reclamation and supply. In 2018, the Duckweed forum
issue 22 described 23 companies in 9 countries,
with 4 each working in water quality testing and
water treatment (Shoham 2018). Provided the
perpetual rise of water pollution and increased
testing, and the roughly 50% lower capital and
operating costs of duckweed (Skillicorn 2013)
and constructed wetland (Zhang et al. 2014b)
treatment systems compared to their bacterial
counterparts, these industries are expected to
grow, likely more so in developing countries.
Sadly, 14 years of satellite observations reveal
decreasing clean water availability across the
world and in heavily populated areas like California, the Middle East, Northern India, and
Northern China where groundwater is being
depleted (Rodell et al. 2018). Many regions
suffer clean water scarcity for at least 1 month of
the year resulting in inadequate supply for people
as well as agricultural losses. Duckweed treatment systems to reclaim water, as well as water
efficient duckweed crops, with many other measures, might be utilized in these and other regions
to increase supply. Similar to water reclamation,
there is a lesser known need for phosphorous
reclamation, since our current practice is to mine
and refine phosphorous deposits, fertilize our
crops, and then let the phosphorous run directly
off of fields and into the ocean, or through our
wastewater treatment systems into the ocean
where it causes eutrophication damage like the
Gulf of Mexico hypoxic zone. Economically
mineable, organically available phosphorous is
expected to be scarce by 2050 or 2100, and
production might decline by 2030 raising its
price possibly beyond the reach of poorer farmers (Childers et al. 2011). Fortunately, phosphorous can be recycled by better farming practices
or by using more aquatic plants and other
methods to recapture more than the current rate
of 50% from human wastes. While phosphorous
is a critical macronutrient and prime example,
many other fertilizers have similar life cycles and
would follow the phosphorous in any reduce,
recapture, and reuse applications. Given the
water and fertilizer scarcities this century will
12
P. Fourounjian et al.