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The researchers have developed an efficient and economical process that might be deployed on a large scale and allow access to drinking water even in the most remote places.
This prototype with a surface area of 0.3 m² can make 2 liters of water drinkable per day.
L. Forro
Today, 1,800 children die every day from diarrhea because they drank unsafe water. 1.8 billion people consume water contaminated with faeces and by 2040 most of the world will face insufficient supplies of drinking water. Finding effective and economical ways to decontaminate contaminated water is therefore a major challenge.
An EPFL team led by László Forro has just unveiled the prototype of a filter that runs on solar energy. On a frame, the scientists created a filter made of titanium dioxide (TiO2) nanowires. On their own, they can already purify water in the presence of sunlight. But the team has additionally interwoven them with carbon nanotubes, which adds an extra layer of decontamination through pasteurization, eliminating human pathogens such as bacteria and large viruses.
Tested with E. coli bacteria
How this system works is as follows: when sunlight hits the filter, its material releases molecules that are reactive oxygen species known to kill pathogens. EPFL tested this prototype with E. coli bacteria and demonstrated its “exceptional ability” to eliminate all pathogens from water. It should work equally well with bacteria causing diarrhea as well as organisms that cause Hepatitis A or Legionnaire’s disease. The researchers believe their filter also shows promise for removing pesticides, drug residues and cosmetics from water.
“Our prototype can provide access to drinking water in sparsely populated and even remote places, and might be easily deployed on a large scale,” explains László Forro. Featured in the magazine «npj Clean Water», the tested device has a surface area of 0.3 m², which makes it possible to supply 2 liters of water per day of decontaminated water. It is easy to increase its surface and therefore the quantity of drinking water produced. “The great advantage of this device is that it is economical, thermally stable and chemically inert.” Improvements are also possible to further increase the efficiency of the filter.
Endre Horváth, lead scientist on the project, says he is “convinced that this will create a strong following in the multidisciplinary scientific communities and hopefully in funding agencies”, which would allow the development and large-scale production of this filter. .
