Likos is familiar with the landscape of Hannibal, which lies 120 miles north of his hometown of St. Louis. He is a new figure, however, in the region's long association with cement. The first workers, like Rosenkrans' Polish great-grandfather, were newly arrived immigrants from Eastern and southern Europe. They mined the limestone right from the river hills, and crushed and cooked it into cement. They returned home to company-owned houses in a company-owned town -- a rough-and-tumble place named "Ilasco," after the first letter in each of the ingredients used to make cement: iron, limestone, aluminum, silica, coal and oxygen.

For the next several decades, Ilasco workers and plant owners were caught up in struggles typical of that period of industrialization: conflicts rooted in prejudice against immigrants, strikes, unionization and workers' safety. They also shared in the plant's prosperity and were proud of their association with one of the nation's most productive cement operations.

Through it all, the grounds and nearby landscape were coated with fine dust created during the manufacturing process. Not surprisingly, today's technology has made capturing and containing the CKD easier. Now it is collected in air filtering and particulate control systems. Some cement companies can even sell CKD to farmers who spread it on their fields as a lime soil amendment. But bulk is the problem. Many plants produce huge quantities of CKD, and managers use landfills to contain the dust above ground or seal it deep in quarry holes left over after the limestone was removed.

The composition of the CKD is determined by its raw materials, as well as by the conditions the dust particles encounter in the kiln. The Environmental Protection Agency says that, in addition to its major constituents, portland cement contains magnesium oxide, sodium, potassium and sulfates. Trace quantities of the metals chromium, lead, zinc and others are often present, depending on the source of the raw materials used to manufacture it.

Continental Cement is one of 13 plants in the U.S. to recover energy from hazardous waste. Because the chemical composition of CKD that emerges from these plants varies widely -- from kiln to kiln, one region of the country to another -- management of the dust is difficult. That's where researchers such as the MU team come in. "One of the benefits of having MU involved," says Greg Haug, president of ReSource Enterprises, an environmental engineering firm working with Continental, "is that they'll publish their findings, and the information will be out there for others." Among those others is Sally Brown, a soil reclamation specialist and research assistant professor of ecosystems sciences at the University of Washington. The university's College of Forest Resources is one of the nation's leading natural resources programs. "CKD is problematic because it has a high pH," she says. "It can burn your skin; nothing will grow on it. But it can be a useful tool, or ingredient, for artificial soils and land reclamation."

Brown has worked with artificial soils for 14 years, mixing CKD with biosolids to reclaim land covered with lead and zinc mine tailings. "We've had some great successes with it here in the West," she adds. "Making these types of soils is a relatively environmentally friendly, low-cost approach that makes disposal of a couple of types of unwanted materials possible."