The issue of having clean water to drink has been around for centuries, but it has gained greater attention today in the context of the impact of climate change on human existence.
According to the World Health Organization (WHO), around 1.8 billion people still do not have access to clean potable water, making do with resources that are contaminated by human and animal fecal matter and industrial wastes. From their end, the United Nations Children’s Fund (UNICEF) notes that 1,800 children in developing countries die every day because of diarrhea, cholera, and other diseases caused by the consumption of unsafe water.
To make matters worse, it is expected that a great part of the world will need to deal with the issue of water stress by 2040 if the issue of insufficient water resources is not resolved soon.
Scientists around the world are racing against the clock to come up with viable solutions to the potable water crisis, and a team at Switzerland’s Ecole Polytechnique Federale de Lausanne (EPFL) has come up with a revolutionary filtration solution powered by the sun.
According to team leader László Forró, they have created a filter made up of titanium oxide (TiO2) nanowired and carbon nanotubes that are activated by UV light. On their own, the TiO2 nanowires can purify water properly if exposed to sunlight.
But the effectiveness of these nanowires is considerably improved when woven with carbon nanotubing, creating a composite material which further decontaminates the water through pasteurization. The process then kills off both bacterial and viral human pathogens.
The Principle Behind the Technology
Based on the team’s findings, when UV light from visible sunlight strikes the filter, it causes a chemical reaction that results in the formation of Reactive Oxygen Species (ROS) molecules, including hydrogen peroxide, hydroxide, and pure oxygen, all of which are known to be effective against pathogenic material.
The team tested the device on E.coli bacteria, though it is expected to be just as effective in removing Campylobacter jejuni (which is the primary pathogen causing diarrhea in much of the developed world); Giardia lamblia which causes intestinal infections; salmonella, cryptosporidium, as well as the bacteria that causes Hepatitis A and Legionnaires’ disease.
Findings also show that the filter may also be used to remove micropollutants to make water more potable.
According to Forró, the filter’s current prototype can help supply clean water for small populations located in distant areas and that the technology is easy to scale up.