State-of-the-art technology can clean wastewater from swine production

WASHINGTON – The attorney general of North Carolina and Smithfield Foods have selected technology adapted by Agricultural Research Service scientists in Florence, S.C., to clean up and dispose of manure from swine-production wastewater at a 4,360-pig farm in North Carolina’s Duplin County.

Replacing lagoons. The new technology will be used by Smithfield Foods to replace current lagoons for cleaning up wastewater in the state’s hog operations.

Swine production in the United States is increasing rapidly. In North Carolina alone, it grew from 2.6 million hogs in 1990 to more than 9 million in 1997. The expansion has caused waste-treatment problems that are one of the region’s greatest environmental issues.

These problems are related to flushing waste from high-density confinement facilities into anaerobic lagoons and then applying the wastewater to cropland. Besides nitrogen, swine manure contains phosphorus and other chemicals that can fertilize plants. But land application can become problematic when more manure nitrogen is applied than crops or forage can use.

Trapping bacteria. A team of USDA colleagues devised an innovative way to remove the ammonia form of nitrogen from swine manure quickly, effectively and relatively inexpensively.

They adapted a Japanese state-of-the-art technology for treating municipal wastewater with large populations of nitrifying bacteria entrapped in polymer gel pellets.

The full-scale treatment system to be built in Duplin County will separate solids and liquids, make a soil-less growth medium from the solids, remove the nitrogen and phosphorus from the wastewater, and recycle clean water for the cleaning of the swine houses.