The News

Nanotechnology for clean water: Facts and figures

Monday, 11 May 2009 06:52 Lily Wang

Nanotechnology could help give millions clean drinking water. David J. Grimshaw outlines the potential, the progress and some of the risks.
Technology has long been important in providing clean drinking water and irrigation for food crops. Indeed, people have had water technology for thousands of years — the Romans were using aqueducts as conduits for drinking wateraround 300BC. But making modern technology accessible and affordable to the global poor is a daunting task. Can nanotechnology perform better than previous technologies?

Water is a scarce resource, and for many countries — particularly those in the Middle East — supplies already fall short of demand. With the pressures of climate change and population growth, water will become even scarcer, especially in developing regions. Moreover, in these regions, what water is available is often unsafe to drink

The quest to ensure that all people have access to clean drinking water is now enshrined in the UN's Millennium Development Goals, which aim to halve the proportion of people without sustainable access to safe drinking water by 2015. According to the World Water Assessment Programme, that will mean improving water supplies for 1.5 billion people.

But how to achieve this? Economics or technology have often driven approaches to providing water for poor communities. The economics route might typically centre on the importance of regulations, institutions and open markets. The technology approach might focus on designing a water pump, filter systems or novel applications, for example, of nanotechnology.

Nanotechnology's potential

Unlike other technologies, which have often sprung directly from a particular scientific discipline, nanotechnology spans a wide spectrum of science. Essentially, it is defined by the scale it operates at. Nanoscience and nanotechnology involve studying and working with matter on an ultrasmall scale. One nanometre is one-millionth of a millimetre and a single human hair is around 80,000 nanometres in width. [3] This kind of scale is difficult for us to visualise but if the distance between the Sun and the Earth were one metre then a nanometre would be the size of a football pitch.

The nanoscale deals with the smallest parts of matter that we can manipulate. Operating at the nanoscale makes assembling atoms and molecules to exact specifications easier. Rather like building a model from Lego bricks, we might envisage creating new materials or modifying existing ones. In applications like water filtration this means materials can be tailored, or tuned, to filter out heavy metals and biological toxins.

Materials at the nanoscale often have different optical or electrical properties from the same material at the micro or macroscale. For example, nano titanium oxide is a more effective catalyst than microscale titanium oxide. And it can be used in water treatment to degrade organic pollutants. But in other cases, manufactured nanoparticles' small size may make the material more toxic than normal.

The principal way nanotechnologies might help alleviate water problems is by solving the technical challenges that removing water contaminants including bacteria, viruses, arsenic, mercury, pesticides and salt pose.

Many researchers and engineers claim that nanotechnologies offer more affordable, effective, efficient and durable ways of achieving this — specifically because using nanoparticles for water treatment will allow manufacturing that is less polluting than traditional methods and requires less labour, capital, land and energy.

New technoloies in the past have made similar claims. Yet if we could develop new business models that let us use nanotechnologies sustainably to solve real problems, identified in participation with local communities, we might have cause for optimism.

The story so far

A range of water treatment devices that incorporate nanotechnology are already on the market, with others either close to market launch or in the process of being developed.

Nanofiltration membranes are already widely applied to remove dissolved salts and micro-pollutants, soften water and treat wastewater. The membranes act as a physical barrier, capturing particles and microorganisms bigger than their pores, and selectively rejecting substances. Nanotechnology is expected to further improve membrane technology and also drive down the prohibitively high costs of desalination — getting fresh water from salty water.

Researchers are developing new classes of nanoporous materials that are more effective than conventional filters. For example, a study in South Africa has shown than nanofiltration membranes can produce safe drinking water from brackish groundwater. [6] And a team of Indian and US scientists have developed carbon nanotube filters that remove bacteria and viruses more effectively than conventional membrane filters.

Naturally occurring attapulgite clays and zeolites are also used in nanofilters. These are locally available in many places around the world and have innate nanometer-size pores. A study using attapulgite clay membranes to filter wastewater from a milk factory in Algeria has shown they can economically and effectively reduce whey and other organic matter in wastewater, making it safe to drink.

Zeolites can also be fabricated. They can be used to separate harmful organics from water and to remove heavy metal ions. Researchers at Australia's Commonwealth Scientific and Research Organization have created a low-cost synthetic clay, hydrotalcite, that attracts arsenic, removing it from water.

They have suggested a novel packaging for this product for low-income communities — a 'teabag' that can be dipped into household water supplies for about 15 minutes before drinking. And selling the used teabags back to the authorities might increase recycling and help with waste disposal of concentrated arsenic.

Nano catalysts, magnets and detectors

Nanocatalysts and magnetic nanoparticles are other examples of how nanotechnology could make heavily polluted water fit for drinking, sanitation and irrigation. Nanocatalysts owe their better catalytic properties to their nanosize or to being modified at the nanoscale. They can chemically degrade pollutants instead of simply moving them somewhere else, including pollutants for which existing technologies are inefficient or prohibitively expensive. Researchers at the Indian Institute of Science, in Bangalore, have used nano titanium dioxide for this very purpose (see 'Nanoscale water treatment needs innovative engineering').

Magnetic nanoparticles have large surface areas relative to their volume and can easily bind with chemicals. In water treatment applications, they can be used to bind with contaminants — such as arsenic or oil — and then be removed using a magnet. Several companies are commercialising such technologies and researchers are frequently publishing new discoveries in this area.

For example, scientists at Rice University in the United States are using magnetic 'nanorust' to remove arsenic from drinking water.

Nanorust's large surface area means it can capture one hundred times more arsenic than larger counterparts. The team projects that 200–500 milligrams of nanorust could treat a litre of water. And it is developing a way of creating nanorust from inexpensive household items. This could significantly reduce production costs, making it a viable product for communities throughout the developing world.

As well as treating water, nanotechnology can also detect water-borne contaminants. Researchers are developing new sensor technologies that combine micro and nanofabrication to create small, portable and highly accurate sensors that can detect single cells of chemical and biochemical substances in water. Several research consortia are field testing such devices and some expect to commercialise these soon. For example, a team at Pennsylvania State University in the United States has developed a way of detecting arsenic in water by using nanowires on a silicon chip.

Nano research in the developing world

Research spending on nanotechnology in developed regions like Europe and the United States are very high as governments continue to prioritise technologies they think will underpin economic growth. And some intermediate countries, like China, are also investing heavily.

South Africa has developed important capabilities in nanotechnology through its National Nanotechnology Strategy, launched in 2006. [15] It has, for example, set up innovation centres for nanoscience in two of the country's science councils. One of these includes a focus on nanoscience for water. The thrust of research here has very much been on solving local problems. The University of Stellenbosch, for example, is researching nanomembranes for water filtration.

India too has invested heavily in nanotechnology — although figures are difficult to verify, partly because investment is often a partnership between government and the private sector.

And other developing countries are increasingly seeing a need to support nanoscience, including research into how nanotechnology can help deliver clean water. Brazil, Cuba, Saudi Arabia and Sri Lanka all host nanoscience centres working on this issue. And the number of patents on nano-based inventions filed by developing country researchers is increasing rapidly.

Developments for the developing world

Some interesting products are now emerging from developing countries, and other products are being developed elsewhere that are highly relevant to the needs of the South (see Table 2).

Product
How it works
Importance
Developer

Nanosponge for rainwater harvesting
A combination of polymers and glass nanoparticles that can be printed onto surfaces like fabrics to soak up water
Rainwater harvesting is increasingly important to countries like China, Nepal and Thailand. The nanosponge is much more efficient than traditional mist-catching nets
Massachusetts Institute of Technology, United States

Nanorust to remove arsenic
Magnetic nanoparticles of iron oxide suspended in water bind arsenic, which is then removed with a magnet
India, Bangladesh and other developing countries suffer thousands of cases of arsenic poisoning each year, linked to poisoned wells
Rice University, United States

Desalination membrane
A combination of polymers and nanoparticles that draws in water ions and repels dissolved salts
Already on the market, this membrane enables desalination with lower energy costs than reverse osmosis
University of California, Los Angeles and NanoH2O

Nanofiltration membrane
Membrane made up of polymers with a pore size ranging from 0.1 to 10nm
Field tested to treat drinking water in China and desalinate water in Iran, using this membrane requires less energy than reverse osmosis
Saehan Industries, Korea

Nanomesh waterstick
A straw-like filtration device that uses carbon nanotubes placed on a flexible, porous, material
The waterstick cleans as you drink. Doctors in Africa are using a prototype and the final product will be made available at an affordable cost in developing countries
Seldon Laboratories, United States

World filter
Filter using a nanofibre layer, made up of polymers, resins, ceramic and other materials, that removes contaminants
Designed specifically for household or community-level use in developing countries. The filters are effective, easy to use and require no maintenance
KX Industries, United States

Pesticide filter
Filter using nanosilver to adsorb and then degrade three pesticides commonly found in Indian water supplies
Pesticides are often found in developing country water supplies. This pesticide filter could provide a typical Indian household with 6000 litres of clean water over one year
Indian Institute of Technology in Chennai, India, and Eureka Forbes Limited, India

Risks and opportunities

Any assessment of future markets for nanotechnology-based water treatments must take account of both the risks and opportunities.

Some researchers claim that investigations into the ethical, legal and social implications of nanotechnology are lagging behind the science.

They quote the low number of citations on such topics in the literature and the fact that, in the United States at least, not all available research funds are being used. For example, the US National Nanotechnology Initiative allocated US$16–28 million to research on nanotechnology's broader social implications — but spent less than half that amount.

And the generally lower scientific capacity in developing countries means it is likely that effective regulation of the ethics and risks of nanotechnologies will lag behind the developed world. Yet there are signs that the ethics of using nanotechnology for clean water are being discussed.

Some researchers have called for more research on the potential health and environmental risks of using nanotechnology for water treatment. For example, there are concerns that the enhanced reactivity of nanoparticles makes them more toxic. Their small size also means they could be hard to contain, so could more easily escape into the environment and potentially damage aquatic life. The full effects of exposure to nanomaterials — from handling them at water treatment plants or drinking them in treated water — are as yet unknown.

But we can make a distinction, in terms of risk assessment, between active and passive nanoparticles. Passive particles, such as a coating, are likely to present no more or less a risk than other manufacturing processes. But active nanoparticles that can move around the environment lead to risks associated with control and containment.

So can nanotechnologies really help solve water problems in developing countries? There are two positive signs that they will. First, water professionals and scientists are increasingly including local communities in dialogues to understand the problems with, and opportunities for, applying nanotechnology to water improvements.

Second, since the commercialisation of nanotechnology is at an early stage, we can hope that such discussions — between researchers, communities and industry — will encourage scientists and businesses to develop appropriate business models to exploit their inventions.

David J. Grimshaw is head of Practical Action's international programme in new technologies and new technologies consultant for SciDev.Net.

Viewpoint] An unhappy China

Tuesday, 07 April 2009 07:33 Lily Wang

China can proudly say as a creditor that America is not right. Unless the United States gives China the treatment it deserves, China will help no more.
April 06, 2009
Lately, the international media have been paying attention to a book published in China titled “China is Unhappy.” The book, written by five writers known for their nationalistic tendencies, became an instant bestseller after it was published in mid-March.

But why is China unhappy? Why is the world paying attention to this book?

Let’s look at some excerpts:

“Learn from America? The United States is virtually bankrupt already. However, it is not actually going bankrupt because it is like a water demon. Countries around the world have lent to the United States so much that they are all concerned about America’s collapse. The United States lives like a parasite. Its economic system is like a cancer to the global economy. Learn from America? China can learn only bad things from America.”

And: “The United States has no money and its manufacturing sector is crippled. Consumers don’t save and only indulge in spending. This led to the subprime mortgage crisis. Some Chinese still worship Western ideas. They are overwhelmed by the United States, underestimate the caliber of the Chinese people and are about to miss the opportunity that comes along with the global financial crisis.”

Then, finally: “The Chinese people are great. China has to save mankind. Amid the financial devastation, China must lead the world to overcome the crisis. The Chinese people have been given such a critical task.”

The international media are watching the book because it clearly demonstrates the nationalistic global perspective rapidly emerging in China. From this point of view, the Chinese deserve to be unhappy. The source of Chinese pride is the millennium-old conviction that China is the center of the world. However, after the First Opium War in 1840, China was torn apart by the Western powers. And in 1949, after almost 100 years, the communist government was established, and the territory was somewhat united. And during the 40 years of the Cold War, China was overwhelmed by the Soviet Union and the United States.

Since the fall of the Soviet Union and Eastern Europe, China has been working hard for 20 years under American hegemony.

Now in 2009, the 60th anniversary of the Communist Party regime, China can recover its pride. With the money earned from selling goods to the United States, China bought U.S. Treasury bonds. Now that the United States is in economic crisis, China can proudly say as a creditor that America is not right. Unless the United States gives China the treatment it deserves, China will help no more.

This is China’s subjective perspective. Having been hurt and forced to struggle, many Chinese think this way. Of course, it is not the official position of the Chinese government. Yet the absolute majority of the Chinese people shares the perspective, and some of the leaders are considered to be in covert agreement.

Last February, Xi Jinping, the most likely successor of President Hu Jintao, visited Mexico. During a meeting with local ethnic Chinese, he criticized the attitude of the West for pointing a finger at China when the West was at fault. Official Chinese media did not cover the story.

The important thing is that the Chinese government is moving in this direction gradually yet firmly. And in reality, the United States and other countries cannot resist such a move.

More importantly, the Korean Peninsula is most directly influenced by the emergence of China. In particular, China is the only country in the world that can influence North Korea.

If China were not there for Pyongyang, it is doubtful whether North Korea could have developed nuclear and missile programs. If China had not helped the North, it could not have afforded to decline America’s food assistance. Would the North have been able to launch a missile despite U.S. pressure? Could it open and close Kaesong Industrial Complex as it pleases? If China really wants to lead the world, it should understand that some countries, including Korea, could become unhappy because of China. In addition, Korea needs to remind China what it’s like when the shoe is on the other foot.

Leyte’s mango growers eye direct exports to China this year

Friday, 27 March 2009 03:38 by Lily Wang

A MANGO orchard in Panabo City, Davao del Norte. Mango growers in Leyte and Davao are finding new ways to improve farm practices to boost yields that will enable them to export their fruits. The extended hot water treatment (EHWT) facility, the first of its kind in Eastern Visayas, was established last week in Isabel, a coastal town with strong international trading ties.

The extended hot water treatment (EHWT) facility, the first of its kind in Eastern Visayas, was established last week in Isabel, a coastal town with strong international trading ties.

Efforts Made to Ensure Safe Water

Monday, 16 March 2009 06:18 Lily Wang

42-year-old Wang Jianniu turns the tap off in his yard on Saturday, March 14, 2009. All the residents in Qiancheng Village, Zhongmu County, in central Henan Province have used clean tap water as a result of the county's large-scale 'safe drinking water' program. [Photo: CRIENGLISH.com]

To have clean and cheap drinking water was once a long-term dream for many residents living in Zhongmu County in central Henan Province, that is, before a water supply project started in 2006.

When turning the tap off in his yard, 42-year-old villager Wang Jianniu says he will never forget the filthy water his family lived with for decades.

"The water was yellow and had a terrible taste. We could even sometimes see small particles in the water we took from the wells. But now the tap water is clean and tastes really good, sweet and cool."

Wang's family, along with many other households in Qiancheng Village, began using the clean tap water two years ago as a result of the county's large-scale 'safe drinking water' program.

The initiative started in 2005 with the aim of constructing a county-wide network within five years to supply clean water to over 200 thousand residents throughout its 180 villages.

Zhu Dalin, the vice director of the county's water conservancy department, says the project has helped more than 120 thousand people get rid of saline in the water since 2008, while the remaining 80,000 will be able to drink clean tap water within two years.

The Zhongmu County, with a population of about 700,000, is located near the southern bank of the Yellow River, the second longest river in China, and just some dozens of kilometres east of Zhengzhou, the capital of Henan Province.

Zhu said although the Yellow River brings abundant water resources to the county, the shallow underground water there was severely contaminated in the past.

"Due to the county's special position, the shallow underground water there was heavily polluted by both the sewage from Zhengzhou City and the water from the Yellow River which contained many impurities."

Excessive fluorine was also found in the county's shallow underground water that further threatened the health of the local people, who are not able to drill deep wells by themselves, Zhu added.

In order to avoid fluorine poisoning through drinking the water, the local government has decided to build ten water plants over the next few years which can pump up and purify the deep underground water.

"Four water treatment plants have been built with a daily water supply capacity of 10,000 tons each. 100 thousand residents have used the purified water that will cover the whole county when they are completed."

The water treatment plants are controlled by computers and the operation of one plant requires less than 20 workers, Zhu said, adding the only task of the workers is to monitor whether the system is working normally.

Besides the health benefits and convenience of using this water, local residents are also satisfied with the acceptable price which is less than 0.8 yuan (about 11.4 US cents) per tonnage.

Wang Shuming, also from Qiancheng Village, has three family members. He says his family usually spends less than 20 yuan on water per month, although they wash clothes and take showers at home often.

Wang is also content with the easy water fee recharging method via a pre-paid IC card.

"The workers usually come to help me recharge the card as soon as I phone them and the recharging is completed as soon as I insert the card into the reader."

Zhu Dalin said in addition to efforts being made to increase the supply of clean water, the local government has urged all residents to save water, while manufacturers and farmers are also being encouraged to cut their water consumption.

Efforts Made to Ensure Safe Water

Monday, 16 March 2009 06:18 Lily Wang