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Overhead photo showing a full-scale wastewater treatment system and former swine lagoon. Link to photo information
In Duplin County, N.C., a full-scale wastewater treatment system (foreground) that replaced the swine lagoon. Click the image for more information about it.

Patrick Hunt, Matias Vanotti and Ariel Szogi examine sample of calcium phosphate. Link to photo information
Soil scientists Patrick Hunt (left), Matias Vanotti (center) and Ariel Szogi examine a sample of calcium phosphate produced by the wastewater treatment system. Click the image for more information about it.

New System Allows Efficient, Earth-Friendly Use of Hog Waste

By Luis Pons
March 7, 2005

A new method invented by Agricultural Research Service (ARS) scientists and collaborators for treating swine-production wastewater may benefit hog producers and the environment alike.

The researchers--soil scientists Matias Vanotti, Ariel Szogi and Patrick Hunt at ARS' Coastal Plains Soil, Water and Plant Research Center in Florence, S.C.--were impressed with the system's stellar performance during a recent year-long evaluation. According to Hunt, the system converted the evaluation site's brown wastewater lagoon into blue, clean and aerated water. A patent is pending on the system.

Relying on a mix of technologies developed by ARS and companies in the United States, Spain and Japan, the system comprises tanks and staging areas laid out over 200 feet. In three stages, it separates solids from liquids, removes ammonia, recovers soluble phosphorus and processes the solids into plant fertilizer.

The researchers tested the system's ability to eliminate animal-waste discharge--and related release of ammonia, odors and pathogens--to surface and groundwater. They also gauged its ability to stem soil and groundwater contamination by nutrients and heavy metals.

During the evaluation, the system removed more than 97 percent of total suspended solids from wastewater. It also stripped the water of 95 percent of total phosphorus, 99 percent of its ammonia and more than 97 percent of its odor-causing components.

The evaluation was conducted by the inventors and the private firm Super Soil Systems USA of Clinton, N.C., on a full-scale version of the system built at Goshen Ridge Farm in Mount Olive, N.C.

The testing system was constructed as part of an agreement between Smithfield Foods of Smithfield, Va., Premium Standard Farms of Kansas City, Mo., and the North Carolina Attorney General's office to use environmentally superior technology to replace current waste lagoons.

Read more about this research in the March 2005 issue of Agricultural Research magazine.

ARS is the U.S. Department of Agriculture's chief scientific research agency.