A water purification system that uses nanotechnology to remove bacteria, viruses and other contaminants may be able to deliver clean drinking water to rural communities for less than $3 a year per family, according to a new study.
Researchers at the Indian Institute of Technology Madras in Chennai, India, developed a purification device that filters water through a specially crafted mixture of nanoparticles to remove harmful contaminants.
The device, which is currently being tested in communities in India, could offer an affordable way to provide small families with at least 10 liters (2.6 gallons) of safe drinking water per day, said study co-author Thalappil Pradeep, a professor in the department of chemistry at the Indian Institute of Technology Madras. [10 of the Most Polluted Places on Earth]
Silver ions to the rescue
To develop this system, scientists first had to figure out how to remove impurities from water retrieved from wells and other local sources.
"We had to look at several problems with water: One is microbes. Another is bacteria and viruses, and then chemicals, like arsenic, lead and pesticides," Pradeep told LiveScience.
The researchers designed a water filter composed of a grainy mix of nanoparticles — so-called composite nanomaterials — that release a continuous stream of silver ions to destroy microbes in the water.
Silver ions, which flow from nanoparticles when oxidized (a conversion process in which an element or molecule becomes more positively charged), have long been known for their ability to effectively kill bacteria.
Other composite materials in the filter cartridge were added to remove arsenic, pesticides, lead and other heavy metals from the water.
"By combining several materials together, we can have an all-inclusive purifier," Pradeep said. "Everything goes through the filter, passes through these materials, and you finally get clean water."
From left to right: Four vials of composite nanomaterials used in the filter, a sachet containing the materials, a filter cartridge, and a prototype of the water filtration device. (Image: Thalappil Pradeep/Indian Institute of Technology Madras)
Will it work?
The filtration process takes approximately an hour, and the researchers' current prototype containers can hold up to 10 liters of water.
"For a family of five in a rural Indian village, you probably need some water in the morning for cooking and some water for drinking," Pradeep explained. "We figure 9 to 10 liters is good enough for those purposes. Then, you can fill it up again, and you now have 20 liters for the day."
Eleven percent of the global population, or 783 million people, lack access to improved sources of drinking water, according to the World Health Organization and UNICEF Joint Monitoring Programme for Water Supply and Sanitation.
The water purifiers are currently being tested in communities in India, but Pradeep sees potential for them to be used in other rural locations around the world.
"We're implementing this already on a community scale, looking at regional water problems," Pradeep said. "But arsenic is a big problem in Africa and other places, and we are interacting with people about it."
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