Science Scoops: Fragrant Waste?

Traveling past a pig farm on a hot summer's day can be quite the nasal experience—similar to standing in a closed closet filled with rotten eggs. That disgusting odor emanates from pork waste and is also the source of major complaints against factory hog farms in Iowa, our nation's top pork-producing state.

But researchers are on the verge of a major breakthrough in the elimination of hog manure odor. Biologist David Soll (University of Iowa) says that all you need to do is bombard the manure with a little ultrasound. Doing so cuts by 50 percent the buildup of hydrogen sulfide, the key “rotten-egg,” odor-producing gas in hog manure. In addition to being an inexpensive and environmentally safe way to deal with the problem, this is an approach that satisfies scientists, hog farmers, and government officials.

Using ultrasound in search of advances in biology and agriculture is not new. For years, scientists have been using these high-frequency sound waves to induce and hasten biological and chemical changes at the molecular level. 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. When you apply ultrasound to hog waste, it still looks like hog manure but “it definitely has a softer fragrance to it,” says Bruce Rastetter, president of Heartland Pork Enterprises.

This spring, 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. If the results are positive, production of the ultrasound systems could begin this year. We'll just have to wait to smell what happens.

Vocabulary

emanate:
To come or send forth, as from a source.

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Activity

  1. What kind of chemical reaction occurs in the pork waste?
  2. How does the introduction of ultrasound affect this chemical reaction?
  3. Why might using ultrasound be more environmentally friendly than allowing the waste to change naturally or using a chemical method to hasten the change?