As cities expand, encroaching suburbanites are raising a stink about unpleasant odors emanating from neighboring hog farms. But a simple, inexpensive concoction of horseradish root and hydrogen peroxide developed by Pennsylvania State University researchers could help deodorize swine and other animal manure, perhaps putting an end to a festering war of the noses.
The report appears in the June 29 issue of the American Chemical Society’s peer-reviewed Journal of Agricultural and Food Chemistry. ACS is the world’s largest scientific society.
In addition to city folk flocking to the country, hog farms have gotten larger. In 1993, 18 percent of hog operations had more than 5,000 animals, now 53 percent do. The confluence of more people and more pigs has sparked a slew of complaints and litigation.
In 2004, for instance, a state appeals court in Nebraska, a major pork producing state, ruled that a hog farm must compensate its neighbors for enduring smells some described as “a suffocating stench.” In response to complaints, the $40 billion industry that employs 566,000 people nationwide has tried — with mixed results — various solutions including building windbreak walls, pumping the manure directly into the ground and adding manure-eating bacteria to the waste.
“The problem of odors from farm manure has never been solved. Yet it is a problem that needs to be addressed given the strain it puts on the increasing number of people living nearby,” says Jerzy Dec, Ph.D., a PSU senior research associate and a co-author of the new study. “Our new approach is a very simple method that doesn’t really take a lot of time, money or effort to do.”
In laboratory studies, Dec and his colleagues mixed horseradish root — purchased at a vegetable market — with hydrogen peroxide. Horseradish root contains large amounts of peroxidase, an enzyme that when combined with peroxide neutralizes phenols. Phenols are chemical compounds that are a common source of odors in manure.
A panel of six trained odor evaluators randomly sniffed treated and untreated manure samples. Overall, the panelists found the samples treated with the horseradish mixture had odors about 50 percent less intense than untreated ones. Chemical analysis indicated the deodorizing effects lasted for at least 72 hours.
In pilot-scale tests, the horseradish mixture effectively deodorized more than 50 gallons of hog manure, Dec says. Larger tests are planned.
Dec suspects the mixture also will work well on other animal waste. Although the PSU researchers used horseradish root, they believe other plants that are good sources of peroxidase such as potatoes, white radish roots and soybean hulls could be used.
The American Chemical Society is a nonprofit organization, chartered by the U.S. Congress, with a multidisciplinary membership of more than 158,000 chemists and chemical engineers. It publishes numerous scientific journals and databases, convenes major research conferences and provides educational, science policy and career programs in chemistry. Its main offices are in Washington, D.C., and Columbus, Ohio.