To look at Mark Owen's LilyPad water purifiers, you wouldn't think they could do very much. They look like giant cosmetic wipes—the sort of thing you clean make-up with—not an invention that can break down serious contamination.
Well, looks can be deceiving. Owen says the one-meter diameter devices can clean whole ponds, reduce river pollution, and allow farmers to spray purer water onto their crops. The pads pack a fierce, albeit slow-moving, punch.
The LilyPads, which are plastic, contain a mesh with a nano-tech coating. When sunlight hits the surface, it spurs a reaction that breaks down material in the water nearby. The process is sufficient to eliminate E. coli and salmonella, and also helps trap heavy metals, Owen says.
Owen, who lives in Oregon, started working on the mesh seven years ago. While in Japan, he saw a "smog-eating" building (probably covered with titanium dioxide) and wondered if he could adapt the idea for water treatment. His material is related to the photo-reactive coatings seen on a growing number of high-rise buildings.
His company, Puralytics, first developed the SolarBag, which includes the same mesh. Treating up to three liters of water at a time, it's since been sold in 60 countries. The LilyPad is still being trialled and doesn't yet have a release date or price.
One possible application is to clean up ponds that aren't worth dredging and refilling. The LilyPads could offer a speedier alternative to letting polluted water revive itself naturally. You can just leave the devices sitting on the surface for months at a time until they've done their thing.
Another potential application is in stormwater clean-up. Often, heavy rains in cities deliver a lot of unwanted chemicals and metals into streams and rivers. Puralytics is looking at ways to purify contaminated water before it enters, working with a $53,000 grant from Oregon BEST, a nonprofit that funds early-stage cleantech in the state.
And then there's agriculture. Puralytics is working with Driscoll Berry Farms in Mexico to see if the pads purify water used for spray irrigation. At the moment, because water is too contaminated, farmers have to employ flood irrigation (not spraying) which is much less efficient.
Owen says the pads will probably cost between $100 and $500 per square meter, though much will depend on how the Oregon and Mexico pilots work out. The LilyPad is also a finalist in USAID's Securing Water for Food 2014 challenge, which will issue grants of between $100,000 and $3 million soon.