News From Terre Haute, Indiana

July 30, 2013

H2OH!: Researchers discovering how sun power purifies water for arid lands

Howard Greninger
The Tribune-Star

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

But sunshine is.

A group of Rose-Hulman Institute of Technology students has 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 sophomore 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 (70 Celsius) 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 a bio layer that further helps filter out bacteria; however, that bio layer often takes 30 days to create. The solar collector allows for more pure water immediately, said Ashley Bernal, assistant professor of mechanical engineering.

Bernal was among a group of Rose-Hulman faculty members who visited Kenya last year.

“With this system, it could reduce the amount of water-borne diseases,” Mbugua said after the student’s presentation. “The application is quite simple for people to understand,” he said, adding the cost is about $130 for materials. That cost could be lower simply by using sticks to construct a frame for the plastic buckets.

The device can also be built with simple hand tools, such a hand saw, hammer and hand drill, said Gunnar Horve, a sophomore from Clinton, Ill., who is majoring in mechanical engineering.

The water purification device is part of a new team-taught, 12-credit, design-build-communicate course focused on the National Academy of Engineering’s Grand Challenges. This challenge was to put solar energy to work economically. The students began work on the device on July 8.

Julian Sfeir, a junior from New Jersey majoring in mechanical engineering, said the students will next formulate an implementation plan and contact students at Egerton University (an agricultural university in Kenya), who can bring the device to their individual tribes.

Sfeir said students hope to collect data to determine longevity and determine repair costs for the device. The implementation plan includes contacting at least two organizations, such as WaterAid, an international nonprofit organization that seeks to provide safe domestic water in Africa, Asia and Central America.

“If we find that our product ends up being successful, we will be able to work with them, in the long term, to distribute it to other places in the world,” Sfeir said.

Reporter Howard Greninger can be reached at 812-231-4204 or