Chemical Engineering June 2014 - 11

Using algae to clean wastewater . . .
T
echnology developed by Algal Scientific
Corp. (Northville, Mich.;
www.algalscientific.com) uses algae
to remove soluble organics, nitrogen
and phosphorous from medium- to
high-strength wastewaters in a single
step. The technology is an alternative
to multistep treatment processes involving
the use of bacteria and chemical
treatment.
The company's Hypertrophic Water
Treatment Process essentially creates
a controlled algal bloom in compact
growth troughs. The specially
selected and adapted algae species
lowers BOD (biological oxygen demand)
and nutrients from wastewater
to allow the water to meet regulatory
requirements or to reduce wastewater
surcharges.
Because the algae treats organics
and nutrients simultaneously, denitrification
and phosphorous-removal
process steps are eliminated and capital
and operating costs are thus lowered.
Also, the algal treatment process
. . . and to make beta-1,3- glucan
W
ith a separate algae-based technology,
Algal Scientific (see previous
story) has invented a sterile
fermentation process for making beta1,3-glucan
from algae that has lower
costs than those associated with fermenting
the molecule with yeast.
Beta-1,3-glucan is a polysaccharide
that boosts immune-system function
in humans and livestock animals. As
a feed supplement, beta-glucan can
eliminate the use of antibiotics as
growth stimulants, a practice that
promotes the evolution of antibioticresistant
bacterial strains.
Traditionally, beta-1,3-glucan has
results in byproduct biomass, which
can be used as fertilizer or burned for
boiler heat, says Geoff Horst, Algal
Scientific CEO.
Along with developing the algae
species and adapting it to the process
environment, the company has
developed patented protocols for
growing and harvesting the algae
that minimize the physical footprint
of the process. Algal Scientific is now
offering licenses for its wastewater
treatment technology.
been made through yeast fermentation,
but the process suffers from
a number of limitations. " Yeastderived
beta-glucan makes up only
about 5 to 15% of cell weight, and
the compound is locked up in the
yeast cell wall, which lowers its bioavailability, "
explains Algal Scientific's
Horst.
Over 50 wt.% of Algal Scientific's
proprietary algae strain consists of
beta-glucan after fermentation, and
the compound is more bioavailable in
the highly digestible algae meal the
company manufactures. Yeast-based
processes involve costly extraction
This PEM fuel cell has H2 storage built-in
C
onventional hydrogen-based systems
designed to store electrical
energy (from solar arrays, for example)
typically feed electricity to a
proton-exchange-membrane (PEM)
electrolyzer to generate H2 from
water. This H2 is then compressed
and stored in a cylinder, or as a
metal hydride in a canister containing
a powdered metallic alloy. When
electricity is required, H2 is supplied
from the storage cylinder to a PEM
fuel cell, along with O2 from air, and
electricity is generated again. The
conversion efficiencies in the various
stages of such a system lead to
an overall energy efficiency of less
than 50%. To improve this efficiency,
a reversible PEM fuel cell with integrated
metal-hydride hydrogen storsteps
in which the cell wall must be
destroyed and the product isolated.
In Algal Scientific's algae fermentation,
no extraction is needed, so the
product can be manufactured less
expensively, Horst says, making it
cost-effective for a wider range of
applications than when it is made
by yeast.
Algal Scientific started up a commercial
production facility for its
beta-glucan products earlier this
year, and now offers three beta-glucan
powders that can be mixed into
animal feeds or further refined for
inclusion in nutraceuticals.
age - a " proton flow battery " - has
been designed by researchers from
RMIT University (Melbourne, Australia;
www.rmit.edu.au), led by professor
John Andrews.
In the proton flow battery, many
steps in the conventional process that
incur net energy losses and irreversible
entropy gains are completely
avoided. The researchers claim their
system's roundtrip energy efficiency
can be comparable with that of the
best battery types, such as lithium
ion (about 70 to 80%), while storing
more energy per unit mass and volume.
The system can operate either
as an electrolyzer to split water or
as a fuel cell to generate electricity.
In electrolyzer mode, H+ ions
emerging from the membrane enter
the solid storage directly and then
react with electrons and storagematerial
atoms to form a hydride,
without producing any H2 gas. In
fuel cell mode, protons coming out
of the solid storage pass through the
membrane to form water molecules
and generate electricity.
The proton flow battery features
a composite metal-hydride, Nafion
hydrogen-storage electrode. The
Nafion provides a continuous polymer
medium interspersed between
the metal particles in the electrode.
This provides pathways for conducting
protons between the Nafion
membrane of the cell itself and sites
on the metal particles where absorption
of the hydrogen atoms can
take place.
ChemiCal engineering www.Che.Com June 2014 11
http://www.algalscientific.com http://www.rmit.edu.au http://www.Che.Com
Chemical Engineering June 2014

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