Two Princeton engineering groups hope to use technologies based on inexpensive, easily available materials to give villagers in developing countries access to safe drinking water and help create local jobs.
One group led by Wole Soboyejo, a professor of mechanical and aerospace engineering, has developed a ceramic filter made from a clay-and-sawdust mixture to remove pathogenic bacteria from water. Baking the mixture burns off the sawdust, leaving behind tiny pores that block microbes.
Currently available filters and treatment methods based on heat, the sun or chlorine are costly, inaccessible or ineffective. The clay filter developed in Soboyejo’s lab eliminated water-borne diseases within weeks in a Nigerian village near Abeokuta, where the researchers have helped set up a factory. They are now transferring the technology to Burkina Faso and Kenya.
“Local people need to generate income from making these filters,” Soboyejo said. “That’s the key to making this sustainable.”
Other than filter-maintenance, the biggest challenge is educating villagers about sanitation and the filter’s benefits, he said. “You’d think it’s as easy as telling people ‘You should use these because it’s good for you,’” Soboyejo said, “but that’s like telling me to eat salad because it’s good for me.”
Another group led by Peter Jaffe, a professor of civil and environmental engineering, is using apatite, a phosphate compound, to make filters for well water that remove fluoride, which can deform teeth and bones if ingested in high amounts. Lab tests show that apatite composed of lime and phosphoric acid works as well as today’s more expensive activated alumina filters.
Once the engineers optimize the filter’s operation, they hope to test it in a village in India where excess fluoride is endemic and study the spent apatite’s potential as a fertilizer, Jaffe said. “It would be irresponsible if we don’t figure out what to do with the used material,” he said.
Soboyejo and Jaffe, both funded by Princeton’s Grand Challenges program on global health, are now collaborating to develop filters made from both clay and apatite that could remove pathogens and fluoride from drinking water at once.