Lehigh Cement Co. in Union Bridge hopes to be the first plant in North America to burn pelletized sludge as an alternative or supplemental fuel source to the coal that fires its cement kiln. A plan to fuel a kiln at a Carroll County cement factory with Baltimore sewage sludge would be the nation’s first use of so-called "biosolids" as an energy source - a technology that experts say holds great promise.
"People have been trying to do something creative with human waste for a long time," said Dr. Robert Hunt Sprinkle, a physician with a doctorate in public policy at the University of Maryland School of Public Policy in College Park. "If the company has a reliable source of high-quality waste turned into sludge and incinerates at high temperatures, then it is environmentally neutral and sounds good to me," he said. "The health risks with coal combustion easily exceed human waste combustion."
A pound of dried biosolids could do the work of about a half-pound of coal and will burn cleaner than the thousands of tons of coal Lehigh Cement Co. burns hourly, company officials said. The kiln’s high temperatures destroy organic compounds, removing them from the environment, they said.
Lehigh would procure the biosolids from Synagro-Baltimore LLC, which the city pays to haul sludge from its Back River and Patapsco waste-water treatment plants. Synagro produces tons of pellets each day from the sludge. Lehigh also wants to store the pellets in a new 130-foot-tall silo.