College of Engineering News • Iowa State University

Down from the Mountaintop

ABE researchers Jacek Koziel and Steve Hoff work to clear the air between livestock producers and their neighbors.

Jacek Koziel measures emissions at a central Iowa livestock facility

As a young man in his native Poland, Jacek Koziel’s flights of fancy literally took wing on the passage overhead of jets to and from the capital in Warsaw and other major cities of the former Soviet bloc. Tupolev TU-154sAntonov An-26s, and, higher yet, the vapor streams of barely visible MIG fighters on patrol—Koziel would become an aerospace engineer.

Accomplished in math and physics, Koziel won admission to the prestigious Warsaw University of Technology. But two years into his studies, things began to change. His penchant for mountain climbing, he admits, didn’t sit well with his demanding curriculum. Also, with the Soviet Bloc in a state of accelerating collapse throughout the 1980s, the already limited opportunities in aerospace for non-Russian engineers would become even scarcer. So Koziel changed his undergraduate major to mechanical engineering—and kept climbing mountains.

Which brings him to Iowa.

On an ascent of Alaska’s Mount McKinley in 1991, Koziel’s friend and climbing partner suffered severe injuries that put him in the hospital for an extended stay. There, Koziel met a native Iowan who was working in a hospital ministry. They married, and Koziel returned to school, earning a master’s in environmental engineering from the University of Alaska–Anchorage. The couple then moved to Austin, where Koziel enrolled in the doctoral program in civil engineering at the University of Texas, followed by a post-doc at the University of Waterloo in Ontario and an academic appointment with the Texas A&M Agricultural Experiment Station in Amarillo before taking an academic appointment at Iowa State in 2004.

The would-be aerospace engineer had drifted down from the heavens, descended the mountain, and come to earth in Ames, Iowa—elevation 942 feet.

Yet for Iowa State—and Iowa—near-tragedy on the face of Mount McKinley was a fortunate detour, ultimately redirecting Koziel from mechanical to environmental engineering. At Texas, he further refined his focus by looking at air quality issues—specifically, the mass transfer of noxious gases from water to air in municipal sewers. (“You would find very high stripping or mass transfer from liquid to air occurring inside sewers—very close to where people live or work,” Koziel remarks.) And, at Waterloo, Koziel found himself the lone engineer in the research group of Janusz Pawliszyn, an analytical chemist who invented solid-phase microextraction.

“It was a new situation for me,” Koziel observes. “I did a lot of chemical measurements in my PhD, but this was like moving to the major leagues from the farm club. It was wonderful: I was the sole engineer among 20–25 chemists, and I realized some of the things that can be done when you put scientists and engineers together.”

Today, along with ABE colleague Steven Hoff, Koziel is working to expand the pioneering research in livestock odor mitigation of ABE emeritus professor Dwaine Bundy. While Hoff focuses on mitigation strategies and applications, Koziel concentrates largely on chemical analysis of the numerous airborne compounds that constitute the odor from the large-scale feeding and finishing operations that have come to define livestock production in Iowa and elsewhere over the past quarter-century.

An industry altered

That shift in the livestock production model roughly parallels Koziel and Hoff’s professional trajectories as engineers, from their undergraduate careers to the present. The growing presence in Iowa and other farm states of large-scale livestock confinements has given rise to conflicts between producers seeking to site new facilities and residents who must live with the effects of animal wastes on groundwater and airborne emissions from the operations.

Both Hoff and Koziel acknowledge the shift in the production model and the economics and cultural politics associated with that shift. In and before the first half of the 20th century, production was more widely dispersed among smaller operations in the countryside, with swine, beef cattle, and other livestock trucked to markets in large cities such as Omaha, Chicago, and Kansas City, where they were sold, slaughtered, and processed in a concentrated industry that supported the livelihoods of a working class with middle-class aspirations.

That all changed with the growth of a vertically integrated livestock industry in which a relative handful of giant corporations put livestock producers under contract to raise swine and cattle in large confinements, Moreover, the massive stockyards and processors in those Midwestern cities disappeared by the 1980s—and with them the good-paying union jobs that lifted tens of thousands of blue-collar workers into the middle class. Relocated to remote rural areas, the “new” slaughterhouses hired a low-paid workforce composed largely of the rural poor and recent immigrants—both legal and illegal—with no economic or political clout to protect their interests.

In short, an industry that formerly represented the backbone of regional economies now was relegated to the rural margins. On a given day in the mid-20th century, the odor from Omaha’s Union Stockyards and its contiguous processing and rendering plants would cover the sprawling city like a smothering blanket. But, as the city fathers were fond of saying, it was “the smell of money”—their money, the money that literally built the city from the ground up and sustained the dreams of its workers. Today, the odor emanating from an 8,000-sow confinement operation may still be the “smell of money.” But it’s someone else’s money—and therefore someone else’s smell that’s inflicted on their neighbors.

Political agnostics

Although they claim to be agnostic on the politics of pork production, Koziel and Hoff at times find themselves caught in the crossfire of the ongoing battles between large-scale livestock producers and the alliance of rural residents, environmentalists, and political activists arrayed against them. Indeed, the fact that both men have accepted support for their research into odor mitigation from industry associations has led to accusations that the engineers are shills or apologists for producer groups.

Hoff declines to get distracted by the politics, however, and responds to such criticism by turning the question around: Would opponents of the large confinement operations rather he and his Iowa State colleagues not conduct research into odor analysis and mitigation?

“What if the commodity groups didn’t go out and seek research projects to help address these questions?” Hoff asks. “Then what would they be saying? So I give the commodity groups a lot of credit for saying, ‘OK, we’ve got these issues to address; send us a project to address these issues.’”

And, Hoff insists, industry funding has no effect whatever on research. “Basically, I won’t talk about a topic unless I have some scientific information to back me up,” he says. “My discussions and message need to be 100% science based.”

Isolating the troublemakers

Much of that science comes from Hoff’s Air Dispersion Laboratory, the Olfactometry Laboratory founded in 1998 by ABE emeritus professor Dwaine Bundy (today supervised by Hoff), and, increasingly, from the Atmospheric Air Quality Laboratory of Jacek Koziel. While Hoff’s labs focus on mitigation strategies centered largely on measuring and controlling ammonia and hydrogen sulfide emissions from confinement operations, Koziel’s work takes a more analytical approach to the detailed chemical characterization of air samples.

“Often, what we react to as odor is caused by a handful of compounds that are present in air at very low concentrations and that aren’t necessarily dangerous, health-wise,” Koziel explains. “But we are wired in a way to detect them by nose at very low concentrations.”

Building on his work with analytical chemists before coming to Iowa State, Koziel seeks to determine just which chemical compounds—and in what concentrations—make up air samples drawn from livestock confinements or, for that matter, any industrial environment. This includes developing a comprehensive library of compounds that make up the offending air, and then subjecting those compounds to simultaneous sensory and chemical analysis using an array of human subjects screened for demographic balance and sensitivity to the compounds.

“We have found and ranked organic compounds that are mostly responsible for livestock odor,” Koziel observes. “We know there are top-ranking compounds out of hundreds of others we really need to focus mitigation on. And we’ve shown that if we remove or mitigate those key compounds, then we can mitigate the overall odor.”

Koziel’s human test subjects are exposed to an array of compounds that they will categorize based on three points: the essential character of the odor (anything from “rotten eggs” to “dirty socks”—and worse), the intensity of the odor, and what Koziel calls the odor’s “hedonic tone,” i.e., the degree to which it is pleasant or unpleasant on a numbered scale. These reactions are then linked with specific chemicals and gases in the air sample rather than to the sample in general, giving engineers a much narrower target for mitigation.

“This is unique,” Koziel says, “because for many years we had labs or groups that essentially went separately in their own ways. One would do just chemical analysis, but couldn’t tell you what meaning it had in terms of odor, what we should really be going after to mitigate or solve. And then you had people who only worked with the sensory analysis.”

A practical partnership

Integrating the two approaches, however, requires that Koziel partner with an experienced hand at applied odor mitigation. And these days in ABE, that nearly always involves Professor Steve Hoff.

Hoff may be a city boy by upbringing—he’s from the St. Paul suburbs—but he’s no cloistered academic. Unlike colleague Koziel’s serial ascents of several engineering “mountains” before claiming his PhD atop civil engineering, Hoff, to the bemusement of his parents, never wanted to be anything other than an agricultural engineer. Further, when it comes to pig production, Hoff’s rural Hamilton County home lies in the belly of the beast in Iowa.

Originally focused on housing, ventilation, and environmental controls for animals, Hoff jumped into odor mitigation in the 1990s as the political heat rose with the spread of large confinements across the Iowa landscape.

“Politically, it was something that absolutely needed to be addressed,” Hoff acknowledges. But Hoff is no politician—despite moving to the countryside. “I find myself in the middle of both sides of this controversy a lot.”

Consolidation into larger operations, Hoff notes, is a natural evolution for most businesses, ag related or not. So, as with any engineering discipline, he sees his job largely dedicated to mitigating whatever downside might be associated with that consolidation, in this case the inevitable environmental impacts associated with confining thousands—even tens of thousands—of animals in a limited space.

It’s not just the numbers that are daunting, though. Unlike the tightly controlled conditions under which many technologies are developed—think of the “clean rooms” in which microchips are designed and manufactured— the sheer volume and variability of structural and environmental factors frustrate the development of effective remedies for odor. Weather, animal diet, confinement architecture, manure management plans, siting of facilities—these and others make a technology that might do the job for producer A nearly useless for producer B three miles down the road.

“It’s horrible,” Hoff concedes. “The amount of variability we deal with is really, really troublesome. There are so many variables, and it’s so difficult to do controlled, replicated experiments to validate some of these technologies once you get on the farm.”

Mitigation, plain and fancy

It is tempting to think there’s a one-size-fits-all technology to do an end run around such endless variability. Koziel’s favored “magic bullet,” for example, takes the form of ultraviolet (UV) light, which, he claims, has the potential to be a veritable panacea against not only odor, but airborne pathogens as well.

“We can essentially irradiate moving air with UV light and convert or remove up to 100% of key pollutants responsible for livestock odor,” Koziel says. “We’ve shown that happening to various phenolic compounds, volatile fatty acids, sulfur-containing VOCs (volatile organic compounds), also ammonia.”

Using UV light, Koziel says, odorous compounds can be broken down into CO2 and water or ionized, with the resulting ozone converting the VOCs responsible for odor into less offensive forms. But Koziel would be the first to concede that, at least for now, while UV light might work wonders in the highly controlled environs of the lab, it’s not yet ready for the real world of livestock production facilities. Rather than any “magic bullet” technology, effective odor mitigation is typically more a customized proposition, in fact the coordination of any number of approaches from a suite of technologies both simple and sophisticated.

One of the seemingly “simpler” approaches Hoff was involved in studied the use of “shelter belts,” clusters of trees placed strategically around odor sources to encourage air turbulence closer to the livestock facility, thereby diluting odor before it is carried downwind. The experiment, Hoff admits, was only “marginally effective,” achieving no better than a 10% reduction in odor.

For the past several years, Hoff has been experimenting as well with biolfilters at a pig finishing site, where he has divided a barn into two sections—one for treatment with biofilter technologies, the other as an untreated control. But that’s just one barn, he notes, and cites the need for greater funding, which would allow him to generate more statistically significant data by using a number of different livestock facilities having different architectures and practices.

A win-win situation

Further standardization of livestock facilities and production practices, Hoff believes, has made effective odor mitigation more feasible over the course of his career. “Instead of having a thousand different building styles we have to deal with,” he says, “we have a manageable number of styles that have evolved over the past 20–25 years.”

Yet the very standardization that makes Koziel and Hoff’s research and applications more efficient in mitigating odor has, paradoxically, led to further criticism of the industry for its “factory farming” techniques—often from some of the same people protesting the odor.

Whatever the applied technologies—UV light, biofilters, shelter belts, architecture, and more—odor mitigation works best when it works in the most efficient, economical manner possible. Therefore, Hoff notes, technologies that might otherwise be prohibitively expensive to operate become feasible when they operate only when needed. And that, he adds, is only when prevailing atmospheric conditions present a likelihood of transmitting noxious odors downwind to a livestock facility’s neighbors.

In order to maximize the efficiency of any suite of mitigation technologies, then, Hoff has designed what may best be described as an on-site, independent weather station to feed real-time data—wind direction and speed, humidity levels, barometric pressure, and any other factor affecting the downstream transmission of odor—to the control systems operating a facility’s odor mitigation technologies. The weather station’s computer interface reads odor levels at the facility and simultaneously triangulates that information with the weather data and a map of neighboring odor “receptors” within range of the livestock facility’s emissions to determine if and when to engage any or all of the facility’s mitigation technologies.

“If the wind direction is unfavorable for a given receptor, and the atmosphere is such that we know odors will travel a long distance at about breathing height,” Hoff says, “then you should invoke some mitigation strategy or suite of options that gives you this 70% reduction in odor concentration at the source. But if you have no one downwind who is going to be affected by odor from a nuisance point of view,” he continues, “then save the producer from spending money on an odor mitigations strategy when they don’t need to do it.”

Adds Hoff, “It’s a win-win situation for both the receptor and producer.”

Location, location, location

Of course, the best mitigation strategy of all is to site a large livestock facility in a location where it’s unlikely to impact neighbors in the first place. So Hoff and his colleagues have developed an odor dispersion model to help producers optimize siting decisions through a combination of receptor mapping—who are the neighbors? and where are they with regard to the prospective livestock facility?—and a minimum of ten years of historical data from the National Weather Service.

Used in about 150 siting decisions to date, the model has met with a measure of success among both producers and their neighbors. Still, no modeling can accurately predict future results based simply on past performance, and both Hoff and Koziel acknowledge the need for significant research and innovation in odor mitigation strategies and technologies for the foreseeable future. In fact, the researchers just last month put the finishing touches on a report covering their work in the Environmental Protection Agency‘s National Air Emissions Monitoring Study.

“For two years continuously—day and night, 24 hours a day, seven days a week—we have measured concentrations of target gases and dust, ventilation rates, and all sorts of other environmental parameters of a typical swine gestation/farrowing site here in central Iowa,” Koziel says.

“This one project is the largest national air emissions monitoring study to date focusing on livestock and agriculture,” Koziel continues. “The impact of the study will be very significant, because the baseline data will be used to develop emission factors, essentially tools EPA will use to regulate the entire livestock industry.”

Perception vs. reality

Neither Koziel nor Hoff have any illusions that either their own modeling or new EPA regulations based on their studies will settle the conflict between producers and downwind residents anytime soon. Science ends where subjectivity begins, after all, and, ultimately, no amount of studies or statistics can argue with human perception and the emotions it engenders.

Still, as a man of science who himself lives in close proximity with large-scale livestock production, Hoff is perhaps better situated than most to mediate the conflict—while mitigating the source that gave rise to the conflict in the first place.

“I really see both sides of the issue,” Hoff insists. “I see the frustration of community residents. I see the notion, the concern that a property value may be negatively impacted. I see that—I’m living in the community.

“But I also see the huge gap between the perception of animal agriculture in the community and the reality of the receptor in the community,” he adds. “The perception is way worse than reality. And so we’re trying to come up with scientific tools to address this issue—take the emotion out of it.”