A New Waste-handling System for Pig Farms

Source: ARS : News & Events

Blue Lagoons on Pig Farms? A new waste-handling system can make it a reality

In Duplin County, North Carolina, a full-scale wastewater treatment system (foreground) that replaced the swine lagoon. (D033-1) The environment and hog producers alike should benefit from a new way developed by ARS scientists and collaborators to treat swine-production wastewater.

In fact, researchers at ARS’s Coastal Plains Soil, Water, and Plant Research Center in Florence, South Carolina, are delighted with the new system’s stellar performance throughout a recent, extensive evaluation.

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

The system performs three critical processes in animal-waste management: It separates solids and liquids from swine wastewater while recovering organic matter; it removes ammonia from wastewater, using acclimated nitrifying bacteria; and it transforms phosphorus removed from wastewater into a solid, marketable fertilizer while converting leftover effluent into an environmentally friendly liquid crop fertilizer.

"Results showed that this system can have a great impact in animal-waste treatment," says Szogi.

How great an impact?

It removed more than 97 percent of total suspended solids from wastewater during the tests. It stripped the water of 95 percent of its total phosphorus, 99 percent of its ammonia, 98 percent of its copper, 99 percent of its zinc, more than 99 percent of its biochemical oxygen demand, and more than 97 percent of its odor-causing components.

The reduction in fecal microorganisms achieved in this system resulted in disinfected effluent. Says microbiologist Patricia Millner, a project cooperator from ARS’s Environmental Microbial Safety Laboratory in Beltsville, Maryland, "This prevents dispersion of pathogens into soil, water, or air when the treated effluent is sprayed onto fields or recycled into storage ponds."

Indeed, the evaluation site’s old wastewater lagoon was converted into clean, aerated water. "It changed color, from brown to blue," says Hunt.

Minimizing the impact of livestock waste on the environment is one of U.S. agriculture’s major challenges. With swine facilities, the problem is compounded when nutrient-rich waste is flushed into lagoons and then applied to cropland. Problems arise when more nutrients are applied than crops or forage can use, causing excess nutrient runoff that can lead to poor drinking water and oxygen depletion in bodies of water.

The magnitude of this challenge was clear during the evaluation. At its operating peak during the trial, the system processed waste generated by more than 4,000 pigs. On average, 12,700 gallons of manure—containing 176 pounds of nitrogen—were flushed from the complex each day!

via Science Blog