Waste Not: Once-Discarded Fly Ash Now Being Used To Clean Contaminated Water

Drs. Shah Jahanian, assistant professor of mechanical engineering at Temple University, and Hossein Rostami, assistant professor of mathematics and science at Philadelphia University, have been using fly ash, sand, and activating chemicals to create reactive barriers, which can either change or destroy contaminants.

Heavy metal pollution of groundwater is an extremely serious problem and costly to remediate. There are over 200,000 contaminated sites in the Unite States, with the groundwater being contaminated at over 70 percent of those sites, and more than half with heavy metal contaminants.

"Right now, many companies cannot afford to clean contaminated water because the available processes are very expensive, labor intensive, and time consuming," says Rostami, who has been researching constructive ways to use fly ash since the early 1990s and holds two patents related to the subject. "By using these reactive barriers, you can remove 80-90 percent of the heavy metals, and what's left is a lot less damaging and can be cleaned at much less cost."

Thus far, the researchers have been successful at removing nearly 99 percent of cadmium (Cd) and chromium (Cr) from contaminated water, and are still testing the removal of lead (Pb) and mercury (Hg).

Jahanian, who joined with Rostami in 1997, says fly ash--a waste by-product of burning coal to generate electricity--is cheap because power companies don't have much use for it other than as landfill.

Each year, 110 million tons of fly ash is generated in the United States, approximately 1,000 lbs. per person. Less than 30 percent of the fly ash is reused in industrial processes or recycled.

"So we are taking something that is an environmental problem and using it to solve another environmental problem," he says.

The research has been funded by the U.S. Department of Energy, and more recently, the National Science Foundation.