Lehigh Cement Co. is proposing to use as much as 100tpd of pelletized sludge - known as a "biosolid" - as an alternative or supplement to the coal it burns in kilns at its factory in Union Bridge, in Western Carroll. Lehigh, which is based in Allentown, Pa., has asked Carroll County for zoning approval to build two 130ft silos, one of which would store as much as 400t of biosolids. The other would hold products for the company’s milling operation.
Lehigh proposes to haul dried sludge by the 20t truckload from sewage treatment operations in Baltimore City to its plant. It would take about five truckloads a day to keep the process in operation, plant officials said. "We would consume about five tons of biosolids per hour and will be using it to enhance or supplant coal," said Peter Lukas, Lehigh’s plant manager in Union Bridge. "We would have to fill the silo every three days." Lukas knows of no similar operation in the United States, but "this is a common practice all over Europe," he said. He said that the heat that would be used would neutralize contaminants and that the process is environmentally safe.