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Research to Pasteurize Manure Featured at Chesapeake Bay Day

By Don Comis
September 22, 1999

BELTSVILLE, Md., Sept. 22--Agricultural Research Service administrator Floyd P. Horn announced today the start of an experiment to see if pasteurization is an effective means of killing E. coli, Cryptosporidium parvum and other pathogens possibly lurking in cow manure, to make sure it can be used safely to improve soils.

"N-Viro, International, of Toledo, Ohio, has loaned the U.S. Department of Agriculture patented equipment used to pasteurize biosolids--the solids remaining after wastewater treatment," Horn said. "The equipment turns the sludge into 'N-Viro Soil,' a product that meets the strictest federal standards for safe biosolids."

Horn said N-Viro moved the equipment--a vertical and horizontal silo with a manure hopper and mixing bins in between--to a composting facility at USDA's Beltsville (Md.) Agricultural Research Center. He said the equipment mixes recycled materials like cement or lime kiln dust, coal ash from electric power plants, and gypsum with manure. A natural chemical reaction occurs when the lime or other high-calcium material hits the manure, creating heat, ammonia and high pH that kill pathogens.

The equipment can be seen on a tour of the composting facility as part of the first Beltsville Chesapeake Bay Day activities on Sept. 28 at the research center, operated by ARS, USDA's chief scientific agency.

Horn said Patricia D. Millner, research leader of the Soil Microbial Systems Laboratory in Beltsville, has begun experiments to compare pasteurization with composting. Millner said she will assess each system for its ability to kill pathogens and control odor. She will also test a hybrid system that combines quicker composting with the pasteurization technique.

Millner said she wants to see if the pasteurization process will also convert phosphorus in manure to a form less likely to leach into streams and rivers. "We will also test the addition of materials such as alum residue from wastewater treatment plants for their ability to stabilize phosphorus in manure," she said.

Horn said if the experiment works it could help areas such as the Chesapeake Bay both by preventing the escape of pathogens and phosphorus and by providing a safe outlet for two materials found in excess in Chesapeake Bay coastal areas: high-phosphorus chicken litter and harbor dredging spoils.

"We will try pasteurizing chicken manure in a mixture of dredging spoils to convert the spoils into a substitute soil for reclamation of road cuts, strip mines and other degraded soil sites that need topsoil for plant growth," he said.

A complete agenda and free online registration for the Beltsville Chesapeake Bay Day is on the World Wide Web at:

Scientific contact: Patricia D. Millner, Soil Microbial Systems Laboratory, ARS Beltsville Agricultural Research Center, Beltsville, Md., phone (301) 504-8163, fax (301) 504-8370,