Sludge burning tests set to begin

Plant in Union Bridge to experiment with biosolids for 6 months in bid to measure safety


A Union Bridge manufacturer expects to begin test-burning dried sludge as an alternative fuel in its cement kiln early next year, under a process that will be closely monitored by the state and county.

The Maryland Department of the Environment is allowing the German-owned Lehigh Cement Co. to conduct about six months of burning to determine the safety and suitability of using pelletized sludge, known as biosolids, as a fuel. Carroll County has issued a one-year permit that allows the company to store the material in a new silo at its factory.

"Sludge disposal is a major challenge nationally, and we have to make sure this process isn't just moving pollution around," said Thomas A. Burke, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health. "We must make sure that using sludge as an alternative fuel makes good sense for public health."

At the invitation of county officials, Burke will be part of Carroll's monitoring team.

"The one thing I can say is that we will learn from this," Burke said.

A pound of dried biosolids could do the work of about a half-pound of coal and would burn cleaner than the thousands of tons of coal that Lehigh burns hourly, company officials said.

"If the company demonstrates it can meet emissions limitations with alternative fuel, we can modify the permit so Lehigh can conduct the operations," said William Paul, division chief of air quality programs at MDE.

Lehigh would store as much as 400 tons of sludge, trucked from Synagro-Baltimore LLC, in the new 130-foot silo and pump it into its kiln, where it would burn at temperatures as high as 3,000 degrees.

Those high temperatures destroy organic compounds, removing them from the environment, and the resultant ash is incorporated into the cement, company officials said.

"We will start with a low rate of biosolids and run about a half-ton per hour," said Peter Lukas, plant manager. "Our final target is eight tons an hour. We will step up slowly and monitor slowly. This is the test phase for us to gain experience and make adjustments."

Burning biosolids, rather than taking them to landfills, could benefit the Chesapeake Bay, said James Slater, Carroll County's environmental compliance officer. Landfill sludge can cause water quality problems because of nitrogen and phosphorus runoff, he said.

"This process gives us a way to deal with sludge that doesn't involve the potential for water pollution," Slater said. "This is a big deal for the bay, which has, for years, had issues with sludge. Landfills have been the predominant place for disposal because nobody figured out what else to do with sludge."

The Union Bridge factory would be the first in the United States to burn sludge for fuel, although the practice is widespread in Europe. County and state officials, including Paul and Slater, visited several German cement plants in October to see the process firsthand. They were struck by the use of biosolids.

"The trip showed us the process is clearly workable," Paul said. "Several German factories are close to residential communities, and some are in the midst of commercial areas. Europeans are using a variety of alternative fuels, and they can teach us. Their requirements are much more stringent than ours."

Slater, who is convinced burning biosolids is sound science, met with German regulators who discussed the constant monitoring of stack emissions and air quality. He seconded Paul's assessment.

"Europe is regulated to the point well beyond where we are," Slater said. "They are doing it. It can be done."

Also on the trip was Richard Ellman, director of the Maryland Environmental Restoration Group, a privately owned company that works with the state on recycling.

"As long as it is handled properly, burning sludge is good for the future of the country," Ellman said. "It is a product that ain't going away, and this is a wonderful way to use this material."

The test-burning phase will take about six months and will help assure MDE that the process can work in the U.S., Paul said.

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