020826 Ultrasound May Cut Smell of Hog Waste

Iowa City, IA (AP) - Researchers say they've found a way to take some of the sting out of hog manure's stench: Bombard it with a little ultrasound.

David Soll, a biological sciences professor at the University of Iowa, has applied for a patent on ultrasound technology that cuts by 50% the buildup of hydrogen sulfide, a key odor-producing ingredient in hog manure.

Scientists, hog farmers and pork industry officials say the technology could be an inexpensive, environmentally safe approach to deal with a major complaint against factory hog farms in the nation's top pork-producing state.

They say the technology also may be effective in treating waste from dairy and beef cattle and poultry operations.

"When it's been treated, you can still tell it's hog manure, but it definitely has a softer fragrance to it," says Bruce Rastetter, president of Heartland Pork Enterprises. Heartland, the nation's ninth-largest pork producer, contributed toward the research.

Using acoustics in search of advances in biology and agriculture is hardly revolutionary, Soll said. For years, scientists have been using high-frequency sound waves to induce and hasten biological and chemical changes at the molecular level.

Soll said he began working with ultrasound to infuse pesticides into seeds to eliminate the need to spray crops with chemicals after planting.

In lab tests on small amounts of frozen manure, Soll found that ultrasound increased the solubility of the manure, slowed production of ammonia and other potentially harmful gases and hastened the oxidation process.

A large-scale test is under way at a 1,300-head confinement barn south of Alden, a small town in the heart of hog country in central Iowa. For four months, manure collected in a storage pit has been piped up to the barn's ceiling and through a sonification chamber before it's dumped into a nearby lagoon.

Acoustic waves generated by titanium tubes vibrating 20,000 times per second penetrate the manure, breaking chemical bonds and triggering chemical reactions that alter the typical decomposition process.

This spring, researchers will broaden testing to confinement lots of 4,000 hogs, as well as lagoons. A panel of professional smell testers will judge the effectiveness of the technology, comparing the aroma of the treated manure with that of untreated confinement pens and lagoons, Soll said.

If the positive results continue, production of the ultrasound systems could begin next year, Rastetter said.

"People are just dying for a solution to this, the producers as well as those who live nearby," said Soll. "And it's important we find one, because we don't want to shut down one of the state's top industries."

Opponents of large-scale hog operations are skeptical of the technology. Hugh Espey, rural project director for Iowa Citizens for Community Improvement, said making large operations smell better doesn't solve other problems, such as water pollution and the threat posed to smaller, family hog producers.

"Our bottom line is Iowa has too many factory hog farms in the first place," Espey said. "We should be looking at ways to improve sustainable farming by smaller, independent producers. This just gives the bigger operations reason to expand and proliferate."

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