This article was taken from the February 2014 issue of Wired magazine. Be the first to read Wired's articles in print before they're posted online, and get your hands on loads of additional content by subscribing online.
Alfredo Zolezzi's low-cost purifier could transform the lives of some of the planet's most deprived people. Once, Alfredo Zolezzi invented technologies to help corporations refine their oil more efficiently. But in 2009, he refocused on water. "Science and technology are advancing quickly, but our innovations are not always helping the poor," says Zolezzi, 55, founder of the Advanced Innovation Center in Viña del Mar, Chile.
With the Plasma Water Sanitation System (PWSS), contaminated water is pressurised and then pumped into a 32cm-long tube. There it is accelerated to 320m/s to achieve a pressure drop, which transforms the water into a liquid-and-gas steam. A 5,000-volt electrical field ionises it, transforming it briefly into plasma -- a state in which the external structures and genetic material of micro-organisms are destroyed. Finally, the plasma is decelerated and returned to water. "The whole process takes just a few milliseconds," says Zolezzi. It has been in use since August 2011 in the San José de Cerrillos slum in Santiago, Chile, where Zolezzi says it has reduced the incidence of waterborne illness. In tests performed by the US National Sanitation Foundation, the PWSS killed all bacteria and viruses in heavily contaminated water.
Each full-size PWSS device, housed alongside a pump and a water tank in a shipping container, can clean 2,500 litres of water a day: enough for 125 people. Zolezzi says each full-size unit will cost £320 when mass-produced. "But I am not a philanthropist," he says. Instead, by developing compact versions of the PWSS to be sold as kitchen appliances, Zolezzi plans to build a business that makes a profit while helping to solve one of humanity's toughest problems.
Start
The contaminated water enters the Plasma Water Sanitation System in a continuous stream.
Pressure
The water is rapidly pressurised and then pumped into a narrow, 32cm-long tube.
Acceleration
Once inside the tube, the water is accelerated to 320m/s - that's close to the speed of sound.
Pressure drop
This acceleration causes a sudden drop in pressure, and the water becomes a stream of liquid and gas.
Plasma
A 5,000v electrical field is turned on, ionising the steam and turning it into plasma.
All clear
The water is returned to normal pressure and is now drinkable. The entire process takes milliseconds.
Watch Alfredo Zolezzi discuss the PWSS at WIRED2013.
This article was originally published by WIRED UK
