Odor Busters

A multi-faceted approach to odor control balances pH levels in the manure pit while controlling air quality in the pigs' environment above the slats.

Six years ago Dennis Willard built a new, 2,000-head contract-finishing barn. Soon after, he was peppered with odor complaints from neighbors on all sides. The list of complaints leveled at the 81 × 208 ft. unit grew to 50 per day at times. Today, odor complaints have dwindled to just one discontented neighbor.

The answer to Willard's odor-sensitive neighbors' concerns is a novel approach that treats the air space above the slats and the 6-ft.- deep manure-holding pits below as completely separate environments.

In a nutshell, the program the Smithsburg, MD, producer has incorporated focuses on managing the pH balance in the pit so that microorganisms can efficiently break down the volatile fatty acids into odorless gases — carbon dioxide and methane — while also controlling the dust levels in the pigs' environment above. And, as an unexpected benefit, the pigs are performing better.

The odor-busting squad supporting Willard's efforts includes three dedicated professionals who have championed the program through a trial-and-error process.

Leading the charge is Sonny Pusey, swine business manager with Land O' Lakes Feeds, who is also responsible for identifying new product opportunities for the company. In 2000, when he first encountered the odor control program, Pusey promptly wrote a multi-page memo to upper management noting this technology was one to keep an eye on.

The originator of the concept is Gary Rapp, Athens, IL, a self-described entrepreneur with roots in the hog industry. He has shepherded his odor control/air quality philosophy through the development and patenting process.

Finally, Warren Kosman, a professor and head of the chemistry department at Valparaiso University, Valparaiso, IN, conducted laboratory simulations and formulated theoretical understandings.

The Setup

Willard contract finishes for Deer Stone Ag, which has about 24,000 additional feeder pigs finished annually by various growers in Maryland and Pennsylvania. All pigs come from the same genetic base and are fed the same pelleted rations, which provides an opportunity to effectively compare pig performance data. Pigs are delivered to Willard weighing about 45 lb., placed 25-28 per pen, and marketed at about 255 lb. Split-sex and phase feeding is practiced.

Willard's home is just 300 ft. south of the finishing unit. Two neighbors are within about 1,000 ft. of the unit — one to the north, another to the south; 2,000 ft. further down the road in each direction sits two more neighbors. Another neighbor built a new house roughly 2,000 ft. northeast in 1998, the same year Willard built the new finishing facility.

Odor complaints came rolling into the Maryland Department of the Environment for over two years before Willard began phasing in what has become known as Land O' Lakes' “Good Neighbor Program.”

A departmental spokesman indicated the situation was markedly improved, although complaints have not totally ceased. The lone complainant is the homeowner about the length of a football field north of the finishing facility.

For perspective, Willard remembers the circumstances of that person's first complaint: “The last of September the health department showed up here and said they had received a complaint about the odor from pigs in the barn. I said, ‘let me show you these pigs.’ I opened the door, we walked in and there was just new concrete. We didn't have the first pig in there yet.”

“We're not getting complaints from any of the other neighbors (now) — even when we haul manure,” he says.

Pay Attention to Pits

Willard adopted portions of the “Good Neighbor Program” in steps over the past couple of years. He started with the pit.

In an effort to contain pit odor, the first step was to slowly float crude vegetable oil with a mixture of activated carbon oil down the pit wall and onto the slurry surface. This is called the “liquid lid” and its purpose is to seal organic molecules (including the volatile fatty acids responsible for the smell) under the surface.

“We shoot for about one-quarter of an inch of the liquid. With gravity, it seeks its own level,” explains Rapp.

Chemist Kosman says to think of the liquid seal as the equivalent of a Zip-Loc bag. “The seal serves as a Zip-Loc on top of a set of molecules that you really don't want to smell. The idea is to keep the odor inside the bag — or in this case, contained below the seal in the pit. Of course, the animals are constantly depositing new waste into the pit right through the seal, which seals itself up again,” he says. “And, other things contained in the seal solution help slow down the process of the molecules coming through (the liquid lid). It's not just vegetable oil.” The seal is expected to last up to two years.

“Corn oil, soy oil or any cheaper vegetable oil can be used,” Kosman adds.

Once the pit was sealed, Rapp's next step was to adjust manure pH below. Willard's 6-ft. pit has a dividing wall in the center, but ports allow manure to flow between them to equalize manure depth.

An orbiting probe in each pit monitors pH levels near the bottom, where acidity is typically highest. The probe rotates about 10 seconds every hour to keep the filament clean and relay accurate pH readings to a central computer.

“The orbiter is a vital part of the equipment,” explains Rapp, adding that a static probe could form residuals on the sensor that affect pH readings.

“It's the acids that we're trying to attack,” he continues. “Our pH target is set at a maximum of 8.0.”

With pH highs and lows set in the computer, the pH orbiter readings tell the computer when to add an ammonia-based, acid neutralizer (buffer) to the pit.

Two, 3,000-gal. tanks containing the neutralizer solution sit at one corner of the finishing building. When the computer opens a valve, the pump kicks on and the neutralizer is pumped into a manifold of PVC pipes that direct the product to the bottom of the pit. Pressure gauges at the near and far ends of the barn monitor pressure of the whole manifold injection system. Rapp says there's about 2 psi difference between the ends of the manifold.

Orifices mounted in the injectors proportion the flow rate out so that the neutralizer is injected equally from one end of the pit to the other. “That way, we only need to have one point of monitoring (pH), avoiding a bunch of sensory monitors mounted throughout the pit,” he adds.

The computer tracks all injections. For example, if the orbit sensor in Pit #1 reports a pH of 7.4, a computer printout will show the date, the amount of neutralizer injected into the pit and for how many seconds the injection occurred. When the pH hits the 8.0 target, no neutralizer is injected.

What's the big deal about pH? That's where the chemist comes in.

“Primarily, it is acid-base chemistry in terms of the molecules most responsible for odor,” explains Kosman. “I say ‘most’ because there are other molecules in the pit. But the ones most responsible for odor are acids, and we tend to just neutralize them with acid-base chemistry. The problem is, we don't want to go too far because if we do, we're going to really disrupt the anaerobic environment that's in the pit naturally.”

Kosman credits Rapp and his wife, Carrie, for bringing the concept to Valparaiso University. Intrigued, Kosman began simulation experiments in the laboratory. “If we can take care of the volatile fatty acids, we're really taking care of most of what would be the odor problem,” he says. “If they are volatile, they all have one thing in common: your nose can pick it up. They stink. The more we remove volatile fatty acids in the slurry beneath the seal, the less they will disperse in the air above the pit.”

The goal is to create the best possible pit environment so that microorganisms can survive and break down solids. Kosman describes the pit program as a “double-barreled approach,” beginning with immediately neutralizing the volatile fatty acid molecules, thereby allowing the microorganisms to naturally go through the total digestion process, which eventually breaks down almost all of the organic waste to methane and carbon dioxide — both odorless gases.

“We don't have to add enzymes or microorganisms to the pit. Everything is there. However, we do add some chemicals to help keep a neutral environment,” he says.

“So, we're getting rid of the volatile fatty acids in two ways. The first is immediate, acid-base neutralization where the base buffer neutralizes some of the acids right away, but in so doing, it also preserves the anaerobes that continue the (breakdown) process that goes all the way down to methane and carbon dioxide. That's exactly what goes on in anaerobic digesters — except we put it right down there in the pit so you don't smell it,” Kosman explains.

But, he cautions: “Someone with a little chemistry background might think they can do that themselves. The thing you have to watch out for is overdoing it. If you get things too basic, you will begin killing off those anaerobes. That's why we monitor the pH closely. We put the neutralizer in gradually, as we need it.”

Pigs' Living Space

Pusey describes the above-slat challenge as the reverse of what's happening below.

“What takes place in the manure is entirely different than the living environment above the slats,” agrees Kosman. “That's an aerobic environment and the chemistry is entirely different. We have a basic problem that you have to treat with an acid. When the waste breaks down, it primarily releases a ‘base’ into the air — which is ammonia.”

Although ammonia is very water soluble, there is very little moisture above the slats, so high ammonia levels become very noticeable.

The final step in squelching odors in the Willard finisher is the “atomizer,” which disperses a fine mist over each finishing pen. The atomizer solution is a corn oil-based product mixed with four other ingredients. “A lot of people have tried just using an oil, but oil alone won't quite get the job done,” explains Rapp.

The first step in the atomization process is to get the corn oil mixture in suspension. To do so, the product in the mixing tank is actually circulated through the PVC dispersion system placed above the rows of 11.6 × 19 ft. finishing pens.

“The mixing time is set for 7 minutes — the amount of time needed to mix about 55 gal. into good suspension,” Rapp explains. The atomization time is set for 45 seconds, which includes the time to build the pressure to 240 lb., so actual time spent dispersing a 1-micron mist is about 30 seconds. The solution is delivered through nozzles on 10-ft. spacings to ensure each pen is covered thoroughly. About 1.8 gal. of solution are dispersed per cycle.

When the cycle is complete, all liquid drains back to the mixing tank so nothing is left in the line, allowing each cycle to start over new.

Willard manually switches a valve during morning and evening chores to ensure each side receives the daily treatment.

In the end, the atomization solution cuts the dust and ammonia associated with odor.

Production Advantages

The performance of Willard's pigs has improved incrementally as each part of the odor control program has been introduced.

During the last five turns, from July 20, 2001 to June 15, 2003, they incorporated the liquid seal on one side of the barn, then the other. The pit neutralization treatment followed; then one side was atomized, then the other. “That probably explains why each subsequent group has performed better,” says Pusey.

Table 1 compares Willard's last five groups' performance (treated) to his non-treated groups before odor control programs were begun. The only variables in the comparison are the incorporation of odor control technology in Willard's barn, and a sire-line change made by the source herd supplying the pigs. Pig source and nutrition remained the same throughout. Market price was standardized at $40/cwt. for the comparison.

Pusey notes that after standardizing all costs and revenue, Willard's system profited Deer Stone Ag $10.89/head over all costs, including the cost of odor control. “Every year since the treatment began, this farm has generated more income — even after the cost of the treatment,” he says.

Other key data points include feed conversion and daily gain. Willard's feed conversion during the untreated period averaged a respectable 2.71. However, since the treatments were initiated, feed conversion has improved to 2.57. Similarly, daily gains averaged 1.73 lb./day before treatment. They've climbed to 1.88 lb./day since treatment was initiated.

“The percentage of mortality decrease really started to show itself more dramatically once the atomization system was put in,” Pusey notes. Mortality in the last five groups was a mere 1.94%, while morbidity was just 1.41%. “Dennis' numbers are dramatic. We can't say why scientifically, but my observation is that when you take the dust and particulate matter out of the air, the lungs are much healthier and the pigs just do better. It is rare to hear a pig cough in Dennis' barn.”

Pusey prefers to express the treatment and equipment costs on a “per pig” basis. “Essentially, we're looking at an amortized cost over five years of 44¢ in equipment costs/head, and a treatment cost of $2.06, based on the 10,442 pigs Willard has finished,” Pusey says. The total cost for the equipment in Willard's system is $12,300. “We could amortize it over a longer life, say 10 years, and then it really looks good,” he adds.

He also notes that treatment costs for Midwestern producers would be even lower, because their shipping costs would be markedly less than Willard's cost for shipping to the East Coast.

The odor-busting threesome is currently working with Midwestern universities to set up third-party oversight of field data collection on the “Good Neighbor Program.” Interested parties can contact Pusey at (574) 658-4137 (e-mail: Spusey@landolakes.com), Rapp at (217) 968-1611 (e-mail: rapptech@dtnspeed.net) or Kosman at 219-464-5387 (e-mail: Warren.Kosman@valpo.edu).

Table 1. Willard Farm Before and After Treatment and Performance Compared to Others in System