In trials at Premium Standard Farms, oil sprinkling and other techniques improved air quality inside and outside a finishing unit.
Settlement agreements with the state of Missouri and the Environmental Division of the Department of Justice in the last four years have obligated Premium Standard Farms (PSF) to spend millions on technologies to abate odor, reduce nitrogen levels and monitor emissions.
One of their latest projects addresses the Environmental Protection Agency's (EPA) concern for particulate matter emissions under the Clean Air Act. In accordance with the settlement, PSF installed and tested an oil sprinkling system in one of its finishing units. According to Purdue University agricultural engineer Al Heber, who monitors emissions, it is an old idea, revisited.
“Oil has been tested probably a dozen times in the last decade,” said Heber. “It started in Denmark and came to the U.S. by way of Canada. But this is the most complete study.”
Heber has one of a handful of mobile laboratories equipped with sophisticated equipment specifically designed for emissions testing. Housed in a trailer at the Locust Ridge production site near Princeton, MO, instruments measure air exiting two tunnel-ventilated finishing units. In the latest study, one barn received a sprinkling of soybean oil once a day and one served as the control. Barns hold 1,100 pigs.
Early results show oil sprinkling reduced total particulate matter (PM) by 63% when compared to the control barn.
Heber explained that EPA only regulates ambient particles that are less than 10 microns in diameter (PM-10), since particles that small are easily inhaled and have the most potential to affect health. PM-10 emissions dropped by 67%.
Odor emissions in the test building were reduced 35%, non-methane hydrocarbons by 49%, and ammonia by 22%, he noted. However, hydrogen sulfide showed little difference between the test and control. This is expected in a flush-style building because of the short time manure stays in the shallow pit, Heber explained.
The idea did have a downside, however. “Safety was a concern,” said Matt Gabris, director of environmental affairs for PSF. “The application was non-uniform, which made the slats slippery. Oil also stuck to the fan louvers, making them hard to clean.”
The cost of the oil, applied at 1 cc/10.8 sq. ft., was 65¢/pig, according to Gabris.
With only a $500 investment to fit the building with nozzles, Heber regards oil sprinkling as a viable technology. “I think the application distribution problems can be solved. A redesign of the sprinkling system would also improve distribution,” he said.
“The air seemed better in the sprinkled barn. It reduces emissions into the air and improves air quality for the pigs and the workers,” Heber continued. “If odor is carried by dust particles, then there is an advantage there, too. That's why the oil-sprinkling concept is so beautiful. It not only helps outdoor air quality but helps indoor air quality, too. Oil attacks the source of emissions so it doesn't come into the air in the first place.”
PSF followed the soybean oil study with a similar study using natural oils in the same barn. Also called essential oils, the natural oils are like industrial potpourri, and smell like spearmint, pine, cedar and peppermint.
The essential oils were stored in a 55-gal. barrel outside the finishing building and released inside through atomization and vaporization near the ventilation inlet. People working in the barn liked the smell, but it did nothing for dust and very little for odor concentration, said Heber.
“However, odor concentration tells only part of the story. Rating the offensiveness paints a more complete picture of its effectiveness,” he commented. “Odor offensiveness on a scale of 0 to 10 with 10 being worst was 5 in the control barn and 4 in the essential oil barn.”
According to odor panelists who evaluated bag samples of air the next day, the biggest difference in odor was detected with odor offensiveness. They seemed to agree, however, with Heber's personal assessment that the treated barn was definitely better, but still somewhat annoying, because the differences between the two barns were not dramatic. The cost was 7¢/pig.
Along with the National Center for Animal Waste Management and Utilization, Heber is also monitoring emissions from a Bio-Curtain attached to the oil-sprinkled barn. Made by BEI Ag Environmental Solutions, the same company that makes the Bio-Cap lagoon cover (see sidebar), the curtain is designed to filter dust particles without hindering fan performance.
The curtain, similar to landscape felt, nearly encloses the fans and can be custom-fit to most configurations. A Bio-Curtain for a typical 40-ft. wide, tunnel-ventilated finishing barn costs $3,100 to $3,500. PSF has eight Bio-Curtains at its 52,000-head White Tail site, plus the one being tested at Locust Ridge.
Heber said the data from the test will determine whether backpressure significantly reduced fan airflow and whether the curtain noticeably reduced the emission of dust, gases and odor. Smoke tests revealed airflow patterns inside the curtain and suggestions have been given to BEI for further improvement of the Bio-Curtain design.
The data's still out, so anything else is purely anecdotal. But Brian Paulsen, manager of environmental affairs, had this observation on the curtain: “There are a lot of odors attached to dust. I can stand behind it and eat lunch.”
A technology PSF has implemented on one large farm is the advanced nitrification/denitrification (AND) system. It is part of a consent decree with EPA signed last year that requires a 50% nitrogen reduction, a reduction in air emissions and emissions monitoring. The system is removing nitrogen as intended, according to Brian Paulsen, PSF manager of environmental affairs. And odor is considerably less than in the past, he says. The effluent is pumped under a low-pressure, center pivot system up to four miles away. “It has made a tremendous difference. Our applicators say there is essentially no odor.”
Called their baseline technology, AND is a system for economies of scale, says Paulsen: “We evaluate all other technology on this.”
Lagoon covers like the one designed by BEI Environmental Solutions offer potential for reducing odor emissions.
A study evaluating two, next-generation versions of BEI's Bio-Cap cover was conducted at two large production sites in southern Utah. Finishing units using the two covers were compared to a finisher using the original Bio-Cap cover, which was installed in October 2000. An uncovered control lagoon was also included. The units housed 8,000 hogs.
The versions included the Bio-Cap ground cover multi-layer (GCML) and the Bio-Cap non-woven multi-layer (NWML). The GCML has three layers: a top layer of woven, UV-resistant material to prolong life; foam strips in the middle to aid in flotation; and a felt-like layer on the bottom. The NWML also has three layers, with the top and bottom layers comprised of non-woven material with foam strips sandwiched in between.
Southern Utah University researcher Kim Weaver developed air-monitoring protocol for the study in conjunction with Richard Dotson and Dwaine Bundy of Iowa State University (ISU). Air samples were taken about every two weeks for six months. Samples were analyzed by the ISU olfactory lab for odor, ammonia and hydrogen sulfide.
Results showed overall odor was reduced 84% in the covered lagoons, compared to an uncovered anaerobic lagoon. The NWML cover reduced odor the most (358.88 odor detection units), while the GCML Bio-Cap reduced odor the least (381.42).
Ammonia emission testing showed a 66% decrease in emissions in the covered lagoons compared to uncovered, and the GCML reduced ammonia the most. Hydrogen sulfide testing also showed a 95% decrease in hydrogen sulfide emissions in the covered lagoons compared to uncovered. The original Bio-Cap reduced hydrogen sulfide emissions the most, while the NWML reduced it the least.
The Utah results show an overall decrease in odor detection, ammonia and hydrogen sulfide emissions. The multi-layer covers, however, do not have significantly better odor control than the original.
BEI's new covers have twice the life, but cost almost twice as much as the original at around $3.50/sq. yard.
Premium Standard Farms is the company's largest customer, with 93 lagoons currently covered with the original Bio-Cap.
Confinement systems that use outside storage tanks for liquid manure could benefit from a clay pebble that has been an odor reducer in Europe for years.
Called Leka rock, the lightweight clay pebbles float on the surface of a manure tank at the Atlantic, IA, research station. Resembling the popular cereal Cocoa Puffs, the pebbles form a 3-in.-thick layer.
Iowa State University extension agricultural engineer Shawn Shouse says the rock was installed in 1998 and does not appear to have lost any of its effectiveness.
Effluent is easily pumped from under the product and the odor control is excellent. “We can stand around the edge of the tank without any regard for wind direction,” Shouse said. High shipping costs from northern Europe, however, jack up the price to just over $1.50/sq. ft. for the clay cover.