Burning sludge as a fuel could help cut pollution

Carroll plant would be first in U.S. to use biosolids

April 14, 2005|By Mary Gail Hare | Mary Gail Hare,SUN STAFF

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 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. It has requested approval from the county and the state and conducted a test-burn.

European plants have been burning the biosolids for fuel for two decades, said Peter Lukas, plant manger of the Lehigh plant in Union Bridge.

At a plant in Maastricht, the Netherlands, operators fire the kiln with a 30 to 70 mix of biosolids to coal, said Jan Theulen, who helped develop the process for Heidelberg Cement Co., parent company to Lehigh.

Replacing primary fuels with biosolids "is a significant step forward to reduce the greenhouse gases," Theulen wrote in an e-mail in response to a question from The Sun.

But neighbors of the German-owned Lehigh Cement Co. in Union Bridge plant say they do not want to be guinea pigs for a testing process. The Maryland Department of the Environment requires testing before approval, and then, monitoring of stringent standards.

"Why not see if it's safe first, before we find out too late that it is not?" said Judy Smith, a member of Carroll Air, a community environmental group that formed about six months ago to fight what members call "constant pollution" from the plant.

The Mid-Atlantic region faces tremendous challenges disposing of sludge from wastewater treatment plants. Baltimore collects and treats up to 250 million gallons of wastewater daily. The resultant sludge is heat-dried and used for fertilizer.

"If this sludge is already being land-applied, its pollutant profile is not intense," said Allen Hershkowitz, senior scientist with the Natural Resources Defense Council and a former advisor to the Environmental Protection Agency.

Lehigh's kiln would burn the sludge pellets at about 3,000 degrees, "a temperature at which just about anything goes away," Hershkowitz said.

"It will all depend on who is operating the combustion, how well the kiln is maintained, who is overseeing and how well standards are enforced," he said. "There is no question this is better than land filling waste and there are limits to land applications."

Other communities incinerate sludge to dispose of it.

"You can have pollutant-free emissions," said Robert Canham, chief operating engineer at the Prince William County (Va.) Service Authority, which incinerates about 45 tons of biosolids a day for disposal.

"If the kiln is extremely efficient, it could actually help cut down on air pollution. Biosolids burn like fuel. It is like throwing a log on the fire."

Using dried sludge as fuel could solve energy needs and disposal issues, said Tom Burke, associate chairman of health policy at the Johns Hopkins University Bloomberg School of Public Health who recently served as chairman of a National Academy of Sciences panel on biosolids.

"But it all depends on what is in the sludge and what level of treatment it receives," Burke said. "Anything we flush down the sink actually collects in sludge."

In Union Bridge, Lehigh employs nearly 200 people, many of them town residents. For years, residents have complained about the constant dust and noise from the plant and its truck traffic. The state recently fined Lehigh and forced it to hasten work on dust reduction.

"Lehigh has its hands filled with too many other problems without getting involved in some other unproven technology, just because it can," said Smith, who lives near the plant.

Public health issues concern Sher Horosko of Westminster, another member of Carroll Air.

"I want to see the science that says this process is safe," she said. "All the burden of proof for determining the health hazards is on citizens."

Horosko has amassed statistics from the Toxics Release Inventory, established by Congress in 1986, an EPA program where more than 20,000 companies in the United States self-report data.

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