Nuisance farm odor is focus of Iowa State University researcher's work

AMES, Iowa - In the summer months, few people can afford to run their air conditioning 24 hours a day.

And even if you could afford it, there are times during the day when you just don't need it.

Steven Hoff, an Iowa State University professor of agricultural and biosystems engineering, thinks the same logic should apply to odor mitigation for concentrated animal feeding operations.

Hoff has developed a system for operating odor mitigation systems only when the weather is most likely to cause the odors to become a nuisance to neighbors.

Hoff's odor mitigation prototype monitors several climate variables and operates only when neighbors may be effected.

The system is a miniature weather station that includes locations of neighbors as part of its programming.

"The idea is to keep track of atmospheric stability, which we know affects how far odors will travel, and whether a neighbor may be impacted because of the atmospheric conditions - the wind direction, and those types of things," said Hoff.

"But if no one is going to be impacted by the odors emitting from a pig house, let's say, or a poultry house, then save the farmer some money and don't mitigate," he added.
Hoff said the system can be used with any odor-scrubbing system that can be controlled in an ON/OFF mode.

"Whatever the method is, bio-filters, or any other mitigation technique, it will be turned on when the conditions dictate," he said.
The most important weather aspect of the system is monitoring atmospheric stability, according to Hoff.

When the atmosphere is unstable, odors will not travel as far and it will affect fewer neighbors.

When the atmosphere is more stable, odors will travel farther and can be a nuisance to more neighbors, according to Hoff.

"We call it 'impact-based odor control' because the idea is going to be to mitigate only when needed," he said.

Atmospheric conditions that the system monitors most closely are humidity, wind speed, wind direction, temperature and solar impact - all of these are likely to affect stability.

Because two of the important inputs of the system are wind speed and direction, the system can also tell where the odor may be headed.

Hoff and Lun Tong, adjunct assistant professor in agricultural and biosystems engineering, currently can take into account the locations of five different neighbors. Within a year, the program will be able to expand to as many as 20 neighbors that might be affected.

Another benefit of the system is the effect on emissions that have environmental impact.

"This is not geared to gas-emission reduction; however, one of the side benefits is that you are still mitigating some of the gases that have environmental concern," said Hoff.

Through two summers of research, Hoff and Tong have developed a system that will provide "significant reduction in operation time while still maximizing the benefit to the neighbor" and also be affordable for the producer, according to Hoff.

Cost of operation is the greatest limiting factor for current odor mitigation systems, Hoff said. This system will allow producers to invest greater amounts in the mitigation system without having to worry as much about operating costs.

For anyone who lives outside the city, as Hoff does, there are tradeoffs.

"In my business, everybody has a sensor. And everyone's is calibrated a little differently. We all have thresholds. My wife's threshold is lower than mine," he said. "With this system, we are trying to minimize the odor impact of animal production to become less of a nuisance to neighbors."