Motivated by a 1993 cholera epidemic in Asia, Center for Building Science researchers have developed a simple, inexpensive ultraviolet-light-based water purification system ideal for villages in developing nations. In many rural areas, water is disinfected by boiling, an inefficient process that is hampered by fuel-wood shortages and contributes to deforestation, depletion of fuel-wood, and air pollution. Knowing that UV light sources can destroy organisms in water far more efficiently, Derek Yegian, University of California mechanical engineering graduate student, former Center Head Art Rosenfeld and myself investigated the technical and economic possibilities of UV disinfection. The result is a demonstration unit that can treat 30 liters (eight gallons) of water per minute using a 36-watt UV lamp similar in technology to a fluorescent lamp.
The purifier is based on the germicidal property of UV-C radiation (100 to 280 nm), which disrupts the DNA strands within the exposed virus, bacteria, or other waterborne pathogens. Less than one minute of exposure can disinfect contaminated water while costing about 1¢ per metric ton. The group's calculations suggest that the total cost to a village of 2,000 is 2.5 to 5¢ per capita annually-well below the medical costs of treating victims of cholera and other waterborne diseases. Yegian and I organized a workshop on this technology in Bhubaneswar, India, in May 1994. Indian nongovernmental organizations are now field-testing purification units that were manufactured privately in India according to an LBL design. The program received early support from USAID, DOE, UNICEF India, and the Joyce Mertz-Gilmore and Rockefeller Foundations. In addition, General Electric (USA) and Philips Lighting (The Netherlands) donated UV germicidal lamps for this project. Mexico, South Africa, and Brazil have expressed interest in the technology as well, and our research team plans to develop a UV unit that can be built locally for less than $200.
Indoor Environment Program
(510) 486-4651; (510) 486-6658 fax
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