Researchers at Iowa State University have found a useful way to recycle a byproduct from water treatment plants. Hans van Leeuwen, an I-S-U environmental engineer, says the byproduct is called “lime sludge” and there are huge piles of it sitting all over Iowa.Lime is used in the water purification process and this sludge is created in quantities measuring hundreds of thousands of tons in Iowa alone every year. Professor van Leeuwen says the lime sludge can be used to make cement and other road-building materials.He says using lime sludge instead of fresh-mined limestone in cement would save our natural resources and would make use of a waste product that otherwise would cost water treatment plants money to throw out. Van Leeuwen says water plants have to add up to ten-percent to the cost of water treatment to dispose of the sludge.Another possible use for the sludge is as a smoke-stack purification material for power plants. Van Leeuwen says the lime sludge is also being combined with “fly ash,” a byproduct from power plants, to make a new product that may be useful as a structural fill material, like for making highway embankments. The sludge could also be used to combat dust on Iowa’s many unpaved roads.