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.

Cleaning up oil spills with nano and magnets (Video)

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.

      Graph (a)

In the graph (a), it displayed carbon nanotube sponge can float on oil-contaminated water and remove oil with large adsorption capacity and the densification of cubic-shaped sponges into small pellets and fully recovery to original structure upon ethanol absorption.

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 

Cheap, sensitive Stanford sensors could detect explosives, toxins in water, Stanford Report (2009) . Retrieved from

http://news.stanford.edu/news/2009/september21/sensor-detect-explosives-092309.html

 

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.
 

 

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