If the Lehigh Portland Cement Co. burns carbon wastes in its kilns, it would not pose a danger to the environment because the amount of metals emitted would be low, a University of Maryland professor said.
"If you paid an honest chemistry lab $1 million, they couldn't find a trace of this in the environment," said Larry L. Gasner, an associate professor of chemical engineering at College Park who has studied combustion and cement manufacturing.
Heavy metals would be emitted in trace amounts from Lehigh's stacks if the company burned carbon waste from a New Jersey dye company, he said.
But, as often happens with controversial environmental issues, experts can be found to support both sides.
"There is no assurance that complete destruction of organic hazardous waste is routinely accomplished in cement kilns," a Washington consultant wrote in apaper about incineration in cement kilns.
Lehigh is asking the state for permission to burn non-hazardous wastes as fuels in its kilns.
The company has applied to the state to burn a carbon waste usedat a waste-water treatment plant at CIBA-GEIGY in Toms River, N.J. Lehigh says the carbon waste should not be classified as hazardous, but Maryland Department of the Environment officials say the material could be hazardous.
MDE denied Lehigh permission to burn the waste.Lehigh appealed the decision; a hearing is pending.
Gasner lookedat data provided by Lehigh about emissions that would occur if the company burned the carbon waste.
"Most of these things are not scary to me," Gasner said of the organics and heavy metals that would be emitted.
The metals would be emitted in such small amounts that they would not pose a danger, he said.
More benzene -- a flammable, poisonous liquid -- would be emitted by spilling several ounces of gasoline at a service station than would be emitted at Lehigh in a yearif the company burned the carbon, he said.
Also, being in the same room with a cigarette smoker for one hour per year would pose aboutthe same health hazard as living one mile from Lehigh's stack if thecompany burned the carbon, Gasner said. Cigarette smoke contains cyanide and phenols, which are poisonous compounds, he said.
Emissions from burning the carbon waste would be almost identical to burning coal, except the amount of mercury emitted would be higher, Gasner said. But the increase would be small, probably not detectable in testsand not harmful to human health, he said.
"Say 'hazardous waste' and people say, 'Not in my town,' ", he said. "They don't realize so many hazardous wastes aren't scary."
Cement kilns are safe places to burn wastes because they are exposed to temperatures of about 2,700 degrees Fahrenheit and will be in the kilns for about two hours, Gasner said.
Commercial incinerators operate at 1,400 to 1,600 degrees Fahrenheit and hold the wastes for about one second, he said.
Both methods result in wastes being more than 99 percent destroyed, Gasner said.
Most of the metals produced in the burning process latch onto cement dust particles, and most of the dust is caught in electric dust collectors and becomes part of the cement, he said.
The process of melting rock to make cement is more rigorous than burning waste in a commercial incinerator, he added.
Gasner has taught at Maryland for 17 years. He has a doctorate from the Massachusetts Institute of Technology and has been a consultant to corporations on environmental matters for 25 years. He teaches a course that includes a unit on cement manufacturing.
Some 25 of the approximately 125 cement plants nationwide now burn hazardous wastes. Industries pay cement companies to take the wastes, which provide a less expensive fuel source than coal.
Jeffry H. Brozyna, a Lehigh vice president and general counsel, said cement kilns offer the safest place to burn wastes because the temperature is high and the wastes stay in the kilns for a long time. The wastes otherwise might end up in landfills, he said.
"Supplemental fuels can solve environmental problems," Brozyna said. "(Residents) don't want it in their backyard, but it has to be insomeone's backyard."
Edward W. Kleppinger, a Washington environmental consultant and former chemistry professor, disagreed that cementkilns are ideal places to incinerate wastes. Kilns are designed to make cement and are subject to temperature fluctuations, he said.
"You can't serve two masters equally effectively," Kleppinger said.
Until this year, cement kilns also were not regulated in the same way commercial incinerators were, he said.
Hazardous wastes usually are disposed of at the least-regulated and cheapest sites, which havebeen cement kilns, Kleppinger said.
In Maryland, the Department of the Environment must issue a permit for a cement company to burn alternative fuels.