Nanotechnology in Water Treatment
The rapidly increasing population, depleting water resources, and
climate change resulting in prolonged droughts and floods have rendered
drinking water a competitive resource in many parts of the world.
The development of cost-effective and stable materials and methods
for providing the fresh water in adequate amounts is the need of the water
industry. Traditional water/wastewater treatment technologies remain
ineffective for providing adequate safe water due to increasing demand of water
coupled with stringent health guidelines and emerging contaminants. These
issues call for emerging technology - Nanotechnology.
How can nanotechnology help?
The potential impact areas for
nanotechnology in water applications are divided into three categories, i.e.
- Treatment and remediation
Nanotechnology would also provide novel opportunities to develop
more efficient and cost effective nanostructured and reactive membranes for
water purification and desalination. Nanomaterials which could be used in water
purification and desalinations.
- Sensing and detection
It is recognized that there is potential
for nanotechnology to open the door to the development of inexpensive, portable
devices e.g. nanosensors that can rapidly and accurately detect, identify, and
quantify a broad range of chemical substances, toxic agents, environmental
pollutants and contaminants in water. (Stanford Report, 2009)
- Pollution prevention
During the textile manufacturing process,
excess dyes are sometimes discharged as wastewater resulting in water pollution
downstream. Particular attention has been drawn to serious water pollution in
China resulting from indigo dyes used to create the distinctive blue color of
denim blue jeans.
Nanotechnology would help remove
potentially harmful dyes chemicals from water which come up with a cheap and
simple process using natural fibers embedded with nano particles to quickly
remove dye from water.
Adoption - Nanotechnology has the potential to contribute
towards:
Oil Spills
Oil spills from container ships or offshore platforms are a frequent
hazard to marine and coastal ecosystems and an expensive one to clean up.
Combination on nanotechnology and magnetism would succeed in
separating oil from water with the process to pump seawater polluted with oil
out from the sea onto a boat treatment facility. Once onboard, the magnetic
nanoparticles would be added and attach themselves to the oil. The liquid would
then be filtered with the magnets to separate the oil and water, with the water
returned to the sea and the oil carried back to shore to an oil refinery.
Another application for nanotechnology on
cleaning up oil spills is carbon nanotubes which exhibits strong adsorption
affinities to a wide range of aromatic and aliphatic contaminants in water, due
to their large and hydrophobic surface areas.
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Desalination of water
Another challenge is the removal of salt or
metals from water. A deionization method using electrodes composed of
nano-sized fibers shows promise for reducing the cost and energy requirements
of turning salt water into drinking water.
Corry (2008) indicated that we may be able to benefit from carbon
nanotubes in the membranes during the process of desalination. Because the
inside of carbon nanotubes is very smooth, water is transported through them
more easily. And, while the nano pores allow water molecule to flow through,
they stop salt ions, making this method perfect for converting seawater to
freshwater. This method could reduce the energy required for desalination by 30
to 50 percent.
Removal of heavy metal from water
The presence in the environment of large
quantities of toxic metals such as mercury, lead, cadmium, zinc or others,
poses serious health risks to humans. A new type of nanomaterial called
nanostructured silica has been developed to detect and eliminate toxic
contaminants from wastewaters in efficient and economically way. (Hu, Chen & Lo ,2006) .
Context impact and the emerging global opportunity
Shortage of clean water in South Africa
In South Africa, two Nanotechnology
Innovation Centres have been commissioned, and have formed collaborative
partnerships with industry, universities and bodies such as the Water Research
Commission (WRC) to conduct cutting–edge research into nanotechnology – particularly in the
field of water treatment.
In according to the Annual report (2011) published by Department of Science and Technology (DST), the South
Africa government has invested over R170 million on conducting extensive
research into the use of nanoparticles in water treatment and a range of water
treatment devices/sytems that incorporate nanotechnology are already
commercially available
- A partnership between the University of the North West and the Council for Scientific and Industrial Research (CSIR) has developed a treatment plant in the rural village of Madibogo in the North West Province. The plant incorporates ultrafiltration membranes to clean brackish groundwater as the majority of inhabitants depend on groundwater or borehole water for their water needs.
- Ikusasa Water was granted the licence by the patent holders (WRC)to produce the capillary ultrafiltration membranes and membrane systems in a factory located in Somerset West in the Western Cape, in late 2009. Now available to the South African water sector, the CUF provides water for treatment solutions for rural areas.
British Petroleum’s Oil spill of 2010’s
fatal Deepwater Horizon disaster
Oil spills, like the one involving British
Petroleum, can be devastating to our environment, costly, and deadly to marine
life and birds and Gulf of Mexico oil spill in 2010 expected the worst
environmental disaster in U.S. history -- to cost it $40 billion.
Both industry and government has ramped up
efforts to ensure with help new technology and create grants to support the research and development of nanotechnology to better contain and clean up all types of oil spills, along with greater scrutiny so as to ensure this
type of disaster never happens again.
China - largest generator of industrial wastewater
China’s ongoing rapid industrialization,
urbanization, and economic growth contribute greatly to acute water pollution
and scarcity problems. In the projected 12th five-year plan (2011-2015), Chinese government
plans to dedicate 120.13 million cubic meters a day on urban wastewater
treatment processing. (Chamber News, 2010)
Significant deal was completed in China's
water treatment sector in year 2010 - Dais Analytic of the US nailed down their
RMB 327 million agreement with a Chinese engineering consortium to supply
nanotechnology-based clean water treatment equipment and expertise to a
wastewater facility in northern China.
Nanotechnology - potential risk on water treatment
However, Hillie and Hlophe (2007) raised the concerns on the potential health and environmental risks of using nanotechnology for water treatment e.g the vigorous reaction of nanoparticles makes them more toxic; small size of nanoparticles enable them more easily escape into the environment and potentially damage aquatic life.
Conclusion
In view of challenges in catering for increasing demand of clean water, nanomaterials are having various outstanding characteristics that enable them particularly attractive for water purification.
Yet, both business sector and government should not only focus on this benefits, water professionals and scientists should take active role to join hand with local communities to understand, investigate and solve the problems when applying nanotechnology to water improvements. (Boxall. A, Tiede. K & Chaudhry.Q ,2007)
Reference:
Boxall. A, Tiede. K & Chaudhry.Q (2007), Engineered nanomaterials in soils and water: how do they behave and could they pose a risk to human health?, Nanomedicine, Vol. 2, No. 6, Pages 919-927
Boxall. A, Tiede. K & Chaudhry.Q (2007), Engineered nanomaterials in soils and water: how do they behave and could they pose a risk to human health?, Nanomedicine, Vol. 2, No. 6, Pages 919-927
Cheap, sensitive Stanford sensors could detect explosives, toxins in water, Stanford Report (2009) . Retrieved from
Corry.B (2008), Designing Carbon Nanotube Membranes for Efficient Water Desalination, Journal of Physical Chemistry. B, 2008, 112 (5), pp 1427–1434
Hillie, T. and Hlophe, M.(2007), Nanotechnology and the challenge of clean water. Nature Nanotechnology 2, 663 - 664
Hu, J., Chen, G., and Lo, I. (2006), "Selective Removal of Heavy Metals from Industrial Wastewater Using Maghemite Nanoparticle: Performance and Mechanisms." J. Environ. Eng., 132(7), 709–715.
The Annual report (2011), The Department of Science and Technology (DST), Republic of South Africa
The green tech market in China EUSME Centre (2011). Retrieved from http://www.iberchina.org/files/china_green_tech.pdf
The China Greentech Report (2011), China Greentech Initiative, Retrieved from http://www.china-greentech.com/report.
Hu, J., Chen, G., and Lo, I. (2006), "Selective Removal of Heavy Metals from Industrial Wastewater Using Maghemite Nanoparticle: Performance and Mechanisms." J. Environ. Eng., 132(7), 709–715.
The Annual report (2011), The Department of Science and Technology (DST), Republic of South Africa
The green tech market in China EUSME Centre (2011). Retrieved from http://www.iberchina.org/files/china_green_tech.pdf
The China Greentech Report (2011), China Greentech Initiative, Retrieved from http://www.china-greentech.com/report.
The Trouble with Water (Feb-Mar 2010), Chamber News, P.66. Retrived from http://china.ahk.de/fileadmin/ahk_china/Dokumente/GT_10i1_2.pdf
