Environmental concerns

Extension professor’s research aims to reduce hog farm odor using biofilters


Photo: biofilter system

Pork brings us the wonderful aromas of bacon frying, pork chops grilling and ham baking. However, the odor from a hog house is less pleasant.

MU Extension assistant professor Teng Lim and graduate assistant Brandon Harvey examine the material inside a biofilter at the MU Swine Research Center. Lim’s research centers on management systems to minimize odor, dust and gas from swine operations.

A University of Missouri Extension assistant professor of agricultural systems management is researching ways to reduce that odor. With funding from the MU College of Agriculture, Food and Natural Resources, Teng Lim uses biofilters to reduce the odor, dust and gas emissions from typical swine operations.

Lim has evaluated small-scale biofilters at commercial hog farms and concluded that these biofilters could be scaled up to reduce emissions from larger hog operations.

“We are trying to evaluate different potential media to improve the biofilters,” Lim said. He is looking at biofilter materials at the MU Swine Research Center in Columbia. Wood chips are the primary medium used in the filters, though he also uses a puffed plastic material.

The biofilters at the MU hog facility have windows to observe the materials inside and are raised off the ground to keep them away from rodents. The rooms in the research barn have individual ventilation control systems and can be monitored online. The system uploads all data to a server and sends a daily email with data from the previous 24 hours.

Lim said the data lets researchers evaluate whether the pigs are comfortable and monitor temperature fluctuation, humidity and pressure to make sure the whole system is working.

When producers look to expand their operations or build a new barn, neighbors often have concerns about the odors. Lim said biofiltration is one of the least expensive ways to reduce odors and dust and should be part of farmers’ best management practices.

“It also shows they are concerned with taking care of the environment and their neighbors and community as well,” he said.

MU Extension structural engineers, air quality engineers, soil scientists and other specialists are working as a team to evaluate farms and offer recommendations on the best ways to mitigate odor and dust.

Lim is also conducting research on anaerobic digesters, which can help with managing waste and odor and provide a source of energy. Manure from the facility goes through a 21-day biochemical process that produces methane gas, which can be used to fuel generators and boilers, said Brandon Harvey, a graduate assistant working with Lim.

Harvey said a hog farm could meet its energy needs with an anaerobic digester and even earn revenue selling excess energy to the utility. For odor mitigation alone, however, a digester is a much more expensive proposition than biofilters, he said.

“Every farm is different, so we’re trying to provide different options — viable options, sustainable options — for people to use,” Lim said. “As hog operations expand, it is critical that they be responsible for the environment and be responsible for their community and neighbors. We want to make sure they have best management practices to adopt that improve their operations and minimize conflicts in their community.”



In partnership with the USDA's Natural Resources Conservation Service and soil and water districts, MU Extension held 26 Grazing Schools and one advanced school this past year, with an estimated total enrollment of 558. The economic impact resulting from the adoption of pasture renovation practices taught in these schools is estimated at $83.6 million. In 2014, the schools passed two milestones: MU Extension has conducted more than 600 schools and educated more than 15,000 producers since 1997. The total area renovated because of the schools now exceeds 1.6 million acres.