Researchers at a university in Switzerland have harvested water from fog, while also removing pollutants, making it possible to extract drinking water in urban areas with heavy atmospheric pollution.
Powered by solar energy, the ETH Zurich researchers used a mesh lattice coated with a mixture of polymers and titanium dioxide. The polymers ensure that fog water droplets collect efficiently on the mesh and then trickle down into a container. The titanium dioxide acts as a chemical catalyst, breaking down organic pollutants.
Ritwick Ghosh, a scientist at the Max Planck Institute for Polymer Research in Mainz, Germany, conducted the research project at ETH Zurich, where he was able to collect 8% of the water in artificially created fog and break down 94% of added organic compounds.
“Our system not only harvests fog, but also treats the harvested water, meaning it can be used in areas with atmospheric pollution, such as densely populated urban centres,” Ghosh said in a statement.
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The researchers explained that in countries such as Peru, Bolivia and Chile, it’s not uncommon for people who live in foggy areas to hang up nets to catch precious droplets of water during dry periods. This technique, however, also captures air pollution.
By utilizing photocatalytic memory, Ghosh’s fog water mesh technique only requires 30 minutes of sunlight to reactivate the titanium oxide for 24 hours.
In addition to harvesting drinking water from fog, the technology could also recover water used in cooling towers, where water vapour escapes up into the atmosphere.
During Ghosh’s time at ETH Zurich, he was a member of the project group led by Thomas Schutzius, who has since taken up a post as professor at the University of California, Berkeley.
“In the United States, where I live, we use a great deal of fresh water to cool power plants,” says Schutzius in a statement on the project. “It would make sense to capture some of this water before it escapes and ensure that it is pure in case you want to return it back to the environment.”