The Herald Bulletin

August 11, 2013

Students create solar-powered water filter for Third World

By Howard Greninger
CNHI News Service

---- — TERRE HAUTE — In Kenya, purified water is not always readily available. But sunshine is.

Students from the Rose-Hulman Institute of Technology in Terre Haute, Ind., have created a device that fills that void by harvesting solar energy to pasteurize and filter drinking water.

"Purified water is a big problem, as two thirds of Kenya lies in an arid or semi-arid area," said Francis Kimani Mbugua, a geography exchange student from Egerton University in Kenya, who provided Rose students insight into the cultural and geographic aspects of Kenya. "Most water comes from rivers or lakes. Children often drink directly from the lake or river with no purification."

As part of the water purification process, Rose students built a three-legged wooden frame to hold two plastic buckets. One bucket is filled with pea gravel, coarse sand and fine sand.

That bucket is then filled with water, such as from a river or lake. The filtered water drains from holes at the bottom of the bucket.

The water then goes into a second bucket, where it is drained into a garden hose that connects to a 10-foot long galvanized steel pipe.

Around the pipe is an 8.5-foot-long, 47-inch wide solar collector. The solar energy heats the water up to 158 degrees Fahrenheit to kill off bacteria, said Phillip Markison, student project manager and a sophomore from Marengo, Ill., who is majoring in mechanical engineering.

The water purification device was designed for a family of five, from materials easily obtained in Kenya. The device can purify 15 liters of water per day, "and we could probably get close to double or triple that," Markison said.

The device meets Environmental Protection Agency requirements for pH (a measure of acidity or basicity of water), lead, bacteria and water hardness, Markison said.

The sand filter in the bucket develops what's known as a "biolayer," that further helps filter out bacteria; however, that biolayer often takes 30 days to create. The solar collector allows for more pure water immediately, said Ashley Bernal, an assistant professor of mechanical engineering who was among a group of Rose-Hulman faculty members who visited Kenya last year.

The cost of each unit is about $130 for materials, and that could be reduced simply by using sticks to construct a frame for the plastic buckets, Mbugua said.

"With this system, it could reduce the amount of water-borne diseases," Mbugua said. "The application is quite simple for people to understand."

Howard Greninger is a reporter for The Tribune Star in Terre Haute, Ind.