Nanotechnology Science Could Revolutionize Treatment Practices
- By Debbie Bolles
- Oct 01, 2007
The production of minuscule
particles and materials
advances, also known as
nanotechnology, could be
the next greatest innovation
to help water and
wastewater industry professionals
do their jobs.
At the same time, the
unknown effects of
nanoparticles on the environment
pose risks for
wastewater plants in particular, given
the newness of a fast-growing industry
that federal officials have yet to
grasp and regulate.
“In my opinion, nanotechnology
will break through in the next decade
in the water industry. It will help
industry to improve water quality and
reduce costs,” said Jan Hofman of
Kiwa Water Research in Nienwegein,
Many experts agree with Hofman’s
assessment while urging cautious
and slow expansion. Because
nanomaterials are in some cases new
chemicals, they may not react in the
same ways as their well-established
A report by the Project on Emerging
Nanotechnologies called “EPA
and Nanotechnology: Oversight for
the 21st Century” notes that this
industry has moved quickly from the
lab into the marketplace over the past
two years. Today, there are more than
450 manufacturer-identified nanotechnology-
related products in the
commercial market and more than
600 raw materials, intermediate components,
and industrial equipment
items used by nano manufacturers.
For those in the water and wastewater
industries, emerging applications
use nanotechnology to improve
water and wastewater treatment, prevent
water pollution, or clean up
tainted water sources.
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A nano primer
By 2014, according to some estimates, 15 percent
of all goods manufactured globally will
involve nanotechnology. According to one definition
from the U.S. National Nanotechnology
is “the understanding and control of matter
at dimensions of roughly 1 to 100 nanometers.”
A nanometer is a billionth of a meter. To put
that in perspective, a human hair is about 60,000
to 120,000 nanometers wide and a red blood
cell is 2,000 to 5,000 nanometers wide.
Nanoscale particles are so tiny they must
be viewed with super-magnifying scanning tunnel
microscopes. In the Project on Emerging
Nanotechnologies report, categories of nano
materials, processes, and products are as follows:
• Nanoparticles that come from natural
processes or that exist in nature, such as sea spray
containing nano-size particles and most viruses.
• Nanoparticles that are byproducts of
human activities, such as from welding or exhaust
from diesel and gasoline-fueled vehicles.
• Nano manufacturing processes used for
making nanomaterials. New types of microscopes
and ways of handling minute amounts
of materials have made it possible to put things
together atom by atom.
• Nanomaterials developed to take advantage
of the unique properties of nano, such as
nanotubes, quantum dots, and nanocrystals.
• Nanoproducts, which are products containing
nanomaterials. In early 2007, almost 400
nanoproducts were on the market, including
clothing, golf clubs, and milkshakes. Sixty-seven
of these products are cosmetics, the largest single
category, and 18 are sunscreen preparations.
Nanotechnology in the drinking water industry
remains in its infancy. Nevertheless,
research involving applications in this area has
been booming and yielding results that could
make its way into the industry in the coming
Hofman said adsorptive nanoparticles can
be very effective due to their high specific use
area and special surface properties. For example,
specific (magnetic) iron oxide particles
or impregnated carbon nanotubes can be used
to remove heavy metals such as arsenic, mercury,
cadmium, and chromium. Several of
these particles and their applications have
“Tiny particles that will remove pollutants
from the water, in my opinion, many of them
[in the future] are going to be based on nanosized
magnetite particles,” said Pedro Alvarez,
a professor and environmental engineer with
Rice University’s Center for Biological and
Alvarez said such particles work through
magnetic separation properties to treat water.
This technology has been tested in rural
groundwater sources to remove arsenic. A powdery
substance with nanoparticles is mixed into
the water, “sucking up all the contaminants,”
“It’s a very powerful absorbent for heavy
metals that contaminate our waters, particularly
arsenic,” Alvarez said.
This technology, termed magnetic nanosorbents,
was tested in 2006 at groundwater
sources in Brownsville, Texas, and in Managua,
Nicaragua, by Rice University researchers.
“We’re still tweaking a few things, but I
envision this will be very cost-effective to solve
some of the world’s problems of arsenic, primarily
in developing countries,” he said.
Another important nanotechnology development
for water and wastewater industries
and groundwater remediation relates to
improved membrane strength and performance
attributes through use of nanomaterials.
Mark Wiesner, a professor of civil and environmental
engineering at Duke University, has
been researching nanomaterial-enhanced
membranes for the past decade.
“We’re making new anti-fouling membranes,
reactive membranes, and membranes
with improved strength characteristics,” said
Wiesner. “We’re making ceramic membranes
out of nanoparticle precursors which would
replace current methods for making ceramic
These ceramic membranes are made out of
metal-oxane particles. Iron or aluminum
nanoparticles deposit on the membrane surface
and are centered to form the ceramic body.
An advantage, Wiesner said, is that this type
of membrane is environmentally more benign
and more stable than ceramic membranes
made through the conventional sol-gel process,
which involves suspension of particles that can
be unstable and finicky to work with.
Wiesner will work with a startup company,
Oxane Materials, to market the ceramic membranes
constructed through nanotechnology.
Hofman said other interesting research in
membranes involves a new reverse osmosis
membrane for seawater desalination developed
by Eric Hoek at the University of California.
“This membrane will reduce the energy
consumption for desalination with a factor
of 2 and will have improved salt rejection
properties. This membrane is now under
development for commercial application and
has high potential to break through on the
market,” she said.
Nanoparticles also can be used to change
the wettability properties of membranes to prevent
fouling, Hofman said. In addition,
nanoparticles may be used to
detect membrane integrity, which is
important to guarantee their safe
application in disinfection.
and super sensors
Effective tools for water pollution
remediation involve reactive
nanoparticles that can be used to
break down contaminants. Such is
the case with reductive particles like
zero-valent iron that can be used to
treat chlorinated organic compounds
like lindane or trichloroethylene
(TCE). Hofman said another
example involves oxidiative
particles, such as titanium dioxide,
that can be used in combination
with ultraviolet light to oxidize
At Rice, researchers have developed a catalyst
that destroys difficult-to-remove pollutants
such as TCE more than 100 to 1,000 times
faster than existing catalysts. This year, that catalyst
will be tested at a groundwater site in Texas
that’s polluted with chlorinated solvents.
Other nanotechnology applications for the
industry involve the combination of biotechnology
and nanotechnology (quantum dots)
to create powerful sensitive probes that detect
specific DNA combinations, added Hofman.
Ready for nano?
Although numerous products and processes
involving nanotechnology will help the industry
in the coming years, cost is still a prohibitive
factor, as is concern regarding regulation
and the health effects of these new
But, said Alvarez, “the cost of production
of these nanomaterials is dropping very fast as
the volume of production increases.”
While Alvarez forecasts nanotechnologyenhanced
membranes will be an effective treatment
tool for water and wastewater plants,
other nano products would be less practical to
use at the plant level.
“It makes more sense to treat it at the point
of use,” he said, though how that would play
out in reality is unknown at this point. Nanomaterials
already are being used to treat pollution
and hazardous waste.
Cynthia Finley, director of regulatory affairs
for the National Association of Clean Water
Agencies, said one concern is the pass-through
of nanomaterials in treatment plants to drinking
water and wastewater discharges, because
little is known about the health effects of some
of these tiny particles.
“At this point our treatment technology is
not designed [to detect] nanomaterials. If
nanomaterials are in our receiving waters, we
could eventually be required to remove the
nanomaterials from our effluent,” Finley said.
That is why the U.S. Environmental Protection
Agency has launched a Nanoscale
Materials Stewardship Program aimed at
increasing the understanding of this technology
and to ensure oversight of nanoscale industrial
chemicals. The effort will call on manufacturers
of engineered nanoscale chemical
materials to report key information to ensure
J. Clarence Davies, a former EPA official
and senior adviser at the Project on Emerging
Nanotechnologies, terms the agency’s current
“It is essential that EPA move quickly to
recognize the novel biological and ecological
characteristics of nanoscale materials. It can do
this only by using the ‘new uses’ provisions of
the TSCA (Toxic Substances Control Act),”
Davies said in a press statement. “With the
approach outlined by EPA and because of
the weaknesses in the law, the agency is not
even able to identify which substances are
nanomaterials, much less determine whether
they pose a hazard.”
Despite the unknown environmental risks
of nanotechnology, many are convinced the
benefits for water and wastewater treatment
and pollution remediation outweigh any negative
This article originally appeared in the 10/01/2007 issue of Environmental Protection.