Carroll panel OKs plant's plan to burn sludge pellets

The Baltimore Sun

A Carroll County advisory panel approved last night a request from Lehigh Cement Co. to permanently store pelletized sewage sludge, known as biosolids, for burning at its Union Bridge plant.

The Carroll County commissioners are expected to vote on Lehigh's request in the next two weeks, County Attorney Kimberly A. Millender said. After a public hearing, the German company could gain clearance to permanently store the biosolids by mid-September, Millender said.

The Lehigh plant is the first cement factory in North America to burn pelletized sludge in addition to coal to fire its cement kiln, according to Lehigh officials. Yet Lehigh has burned biosolids and other alternative fuels at its European plants for five to 10 years.

After years of dirty emissions, air quality at the cement manufacturing plant has recently improved, said Sher Horosko, a member of the Carroll County Environmental Advisory Council, which backed Lehigh's request yesterday.

"We're come a long way with Lehigh," Horosko said. "Biosolids are a renewable resource."

Lehigh obtained permits and a temporary zoning amendment to begin test-burning the sanitized sludge in early 2006 - a process that has been closely monitored at the state and county level. The county commissioners in September renewed Lehigh's yearlong permit to store as much as 400 tons of dried biosolids in a 130-foot silo built for that purpose on the plant's grounds.

The biosolids - obtained from Baltimore's wastewater treatment plants - are trucked in from Synagro-Baltimore LLC, stored and then pumped into Lehigh's kiln, where temperatures reach 3,000 degrees.

Union Bridge residents initially worried that burning biosolids would create excess odor and pollution. But the town's mayor, Bret Grossnickle, said there are no complaints now. After being treated to remove any detectable bacteria, the sludge pellets are nearly odorless.

Lehigh officials hope to continue firing the plant's rotating kiln with a heat source that is 20 percent biosolids and 80 percent coal. The plant requested permanent approval to burn between 2.2 and 6.6 tons of biosolids per hour.

No solid waste is produced by the biosolids because the burnt ash is used in the clinker, the powdered cement product.

In June, Lehigh's environmental engineer, Kurt Deery, updated the environmental council on the emissions data generated by test-burning the biosolids. Chemical emissions such as nitrogen oxide and sulfur oxide are at or below the levels permitted by the Maryland Department of the Environment, Deery said.

Lehigh is also awaiting final permits from the state environmental department, which should come within three months, Deery said.

laura.mccandlish@baltsun.com

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