A tiny device could solve one of the greatest problems in the developing countries: water contamination. Researchers from Stanford University’s Institute for Materials and Energy Science in collaboration with scientists at the Department of Energy’s SLAC National Accelerator Laboratory have created a sunlight-fueled gadget that killed 99.99 percent of bacteria after 20 minutes of use in 25 millimeters of water contaminated E. coli and lactic acid bacteria produced in a laboratory.
Current methods include boiling water by consuming precious fuel and leaving the liquid in plastic bottles under the sun, a process that can take as long as 48 hours. The new device could significantly cut that time at a very low cost. The researchers published their findings in Nature Nanotechnology last Monday.
Smaller than a postage stamp, the device uses the visible part of the solar spectrum aside from UV rays to disinfect water, humanity’s most precious resource. It is made of glass and invisible layers of a compound called molybdenum disulfide, which becomes a photocatalyst capable of producing a disinfectant known as hydrogen peroxide when it is hit with visible light.
“Our device looks like a little rectangle of black glass,” lead author and PhD researcher Chong Liu said in a press release, as quoted on SLAC’s website. “We just dropped it into the water and put everything under the sun, and the sun did all the work.”
The device uses nanoflakes of molybdenum disulfide, a cheap industrial lubricant that is easy to manufacture. It triggers the formation of disinfectants when placed in direct sunlight. Topped with a layer of copper, the nanoflakes are very thin films that make the device’s surface look like a fingerprint under an electron microscope and the tiny flakes of molybdenum disulfide are arranged like walls on a glass surface, as explained in the report.
Stanford researcher Yi Cui, whose team developed the device, was proud to say how they were able just to design a material and then achieve excellent results. The device left pure water behind in less than half an hour, as postdoctoral Stanford researcher Chong Liu wrote in the report.
Improving people’s lives
The device proved an excellent performance and it shows promise, but Cui acknowledged that further research is needed to be able to achieve the ultimate goal: indeed solve environmental pollution problems to improve people’s lives. The researchers need to prove the device’s efficiency to kill greater amounts of real-life viruses or chemicals, which have a more complex mixture of contaminants than the bacteria produce in the laboratory to test the newly-created object.
Before the device can be sent for commercial production, additional tests will be carried out in rivers of developing countries. Andrew Gordon, the publicist for SLAC, said the device would have to wait up to five years to hit the market.
“There’s a limit of how many bacteria and viruses you can drink before you become sick,” Liu said, as quoted by Mercury News. “Our intention is to solve environmental pollution problems so people can live better.”
Globally, one in nine people lacks access to improved sources of drinking water, and one in three does not have access to improved sanitation, according to UN-Water. About two million tons of human wastes end up in watercourses every day. About 300-400 MT of contaminated waste is dumped in waters every year. In developing countries, as much as 70 percent of industrial waste is dumped untreated into waters where they contaminate the usable water supply.
But agriculture also pollutes water resources, with nitrate being the most common chemical contaminant in the groundwater aquifers worldwide. The food sector produces 54 percent of organic water pollutants in low-income countries.
All this causes 3.5 million deaths every year as so many people lack access to improved water quality, sanitation, and hygiene. Moreover, the biodiversity of freshwater ecosystems has been degraded the most by water pollution.
World Water Week 2016
UN-Water will celebrate the 2016 edition of World Water Day on 28 August to 2 September in Stockholm, Sweden. Sessions will be held on issues related to water and jobs. Those interested in being part of the celebration but are unable to be in Sweden by that time can watch live interviews on UN-Water’s Facebook page every day at 15:30 CET. People from around the world will be able to watch leading experts from the International Labour Organization, the UN Refugee Agency, UNICEF, Water.org and the World Health Organization as they go through the challenges this world is facing.
Another way of digital engagement includes online discussions with Members of UN-Water who will take on the Twitter account for one hour every day to talk about specific topics related to water and the Sustainable Development Goals.
Source: SLAC National Accelerator Laboratory