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Tool determines when water disinfected by sun is safe
University of Washington (UW) engineering students won an international contest for their design to monitor water disinfection using the sun's rays. The students will share a $40,000 prize from the Rockefeller Foundation and are now working with nonprofits to turn their concept into a reality.
Team member Jacqueline Linnes, who recently completed her bioengineering doctorate, traveled to Bolivia last year with the UW chapter of Engineers Without Borders. While there, she and other students treated their drinking water by leaving it in plastic bottles in the sun.
The concept is an old one. Solar disinfection of water in plastic bottles, also called SODIS, is promoted by many nonprofits. It offers a cheap and easy way to reduce some of the roughly 1.5 million diarrhea-related children's deaths each year. But global adoption has been slow, partly because it is hard to know when the water is safe to drink.
UW entered a competition to design an indicator for Fundación SODIS, a Bolivia-based nonprofit dedicated to testing and promoting this method. Solar disinfection in water bottles removes more than 99.9% of bacteria and viruses, with results similar to chlorination. The UW device lets users know when the sun's rays have done their job.
Linnes began working on the problem with Engineers Without Borders members Penny Huang, a senior in chemical engineering, and Chin Jung Cheng, then an undergraduate in chemical engineering and now a UW doctoral student in bioengineering.
At first, the students focused on developing a chemical test strip. Then they considered an electronic sensor and contacted Charlie Matlack, a UW doctoral student in electrical engineering. Together they built a system using parts from a keychain that blinks in response to light. Other electronics monitor how much light is passing through the bottle and whether a water-filled bottle is present, so the system knows when to stop or start recording data.
Winning the contest means the students split the $40,000 prize, and their efforts may improve the health of children around the world. The competition was put on by InnoCentive Inc., a Boston-based company that since 2001 has hosted a website where organizations can post technical challenges with prize money and anybody can submit a solution.
In this case, even the challenges themselves were solicited on the web. GlobalGiving Foundation Inc., a Washington, D.C. nonprofit that acts as a clearinghouse for charitable donations, asked nonprofits around the world to submit technical challenges relating to water quality. It then chose five to post to InnoCentive, and the Rockefeller Foundation supplied prize money.
The challenge called for designs costing less than $10. The UW students estimate their parts would retail for $3.40, and bulk buying could reduce the cost further.
The Sodis Foundation now holds a nonexclusive license to develop the technology. It is also focusing on larger-scale systems that could be used in situations such as disaster relief. A Sodis Foundation donor has also offered Matlack $16,000 to continue developing a prototype of the water bottle indicator. (The contest proposal tested each part of the system separately.)