A pig production operation is easier on the nose and the surrounding environment, thanks to timely assistance from researchers at the University of North Dakota Energy & Environmental Research Center (EERC). Last July, the EnviroPork hog farrowing facility west of Larimore, N.D., faced possible penalties for violating state odor regulations and a potential shutdown because of a lawsuit filed by two local residents. Today, using EERC expertise in odor control technology, the area around the operation is nearly odor free
The solution to EnviroPork's manure lagoon odor problem was low-cost, low-tech barley straw. Using a straw cannon that pulls apart bales and shoots the straw up to 150 feet, barley straw was spread over the two-acre manure lagoon to form an eight- to 12-inch-thick matt covering.
Dan Stepan, an EERC research manager, says that the straw acts as a biofilter by providing a favorable environment for the growth of microorganisms. These microorganisms use the odor-causing compounds as a food source, breaking them down to odorless carbon dioxide and water.
"Barley straw works best because it floats well," says Tom Moe, an EERC research engineer. "The straw has a waxy coating that prevents it from becoming quickly saturated with water."
Another source of odor was EnviroPork's hog barns. During warm weather, large fans are used to ventilate the barns for temperature control. The air coming out of the barns contains small particles of pig dander, feed dust, manure and other compounds that contribute to odor problems. The EERC designed a unique filter system consisting of vertical walls of barley straw. Air coming out of the barns is blown into the straw walls, capturing particles and removing a significant source of odor.
Since the barley straw was applied on EnviroPork's manure lagoon and filter walls were constructed near the hog barns, the results of odor inspections at the facility have dramatically improved.
"I've been extremely impressed with the low odor level around the facility," Baer says. "I'm absolutely amazed that a design this simple is having such a dramatic effect. It's the best money our cooperative has spent."
