Researchers at the University of North Carolina at Charlotte think they've hit upon a simple and cheap way to filter drinking water in underdeveloped nations.
The process — which utilizes sand, a short section of PVC pipe, and common purification chemicals — can be produced onsite by minimally trained workers. Dr. James Amburgey says he hopes the low-tech solution will make fresh water available to millions who are now without safe drinking sources.
Amburgey has been experimenting with ways to add low-cost ferric chloride and a pH buffer to a traditional sand filter. The chemicals force contaminants such as Cryptosporidium oocysts to stick to the sand. The Cryptosporidium's tiny 5 micron diameter would otherwise allow it to pass through the comparatively porous filtration layer.
The UNC method has the additional advantage of speed. The chemical pretreatment yields filtration rates 30 to 50 times faster than more expensive methods, and can also be adapted to local varieties of sand and crushed rock.
A UNESCO report released at the start of an international water conference in Istanbul in 2009 defines fresh water access as one of the world's most pressing health issues. In Africa, half a billion people lack access to a reliable source of safe drinking water. Some 5,000 children die each day from diseases directly related to unsanitary water.
In prototype testing at UNC Charlotte labs, the new filter design removed 99 percent of Cryptosporidium-sized particles in water sampled from local creeks and rivers.