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Evaluation of Design Specifications for a Vertical Bed Biofilter

Dick Nicolai, Associate Professor
Steve Pohl, Professor
Ryan Lefers, Graduate Research Assistant

Funding Source 

South Dakota Pork Producers Association 


Over time, biofilter media containing wood chips and compost will settle and become denser at the bottom of the vertical wall, which results in air channeling. A possible solution is to taper the biofilter media sides (i.e., make them thicker at the top than at the bottom). The objective of this research project is to determine the wall taper that results in uniform airflow after one year of media settling. 

Need or Impact

Odors from livestock facilities are an issue for many communities and livestock producer. Air quality effects from livestock operations have become an environmental, ecological, and sociological problem. Emissions for gases and particulates from livestock operations are considered to be environmental impacts that must be controlled. Odor sources for livestock production systems include buildings, manure storage, and land application of manure. Most complaints have focused on emissions from uncovered outside manure storage. Therefore, the current trend in swine production is to use deep pit manure storage beneath the slatted floor. In this situation, the livestock building becomes a major odor source. Biofiltration is an odor reduction technique that can be adapted to reduce emissions from these mechanically ventilated facilities. 

For biofiltration to be successful, significant land area is needed to effectively treat most, if not all, the exhaust air. For example, to treat 60 percent of the maximum summer ventilation rate of a 1,000 head finisher barn the required land area can equal up to half the size of the building. This approach works well for new design facilities, but there are many existing building locations that do not allow for such area. 

Project Status

Completed and the current report is Design Specification for a Vertical Bed Biofilter. 

Project Results 

Media thickness was determined to be a factor in achieving uniform airflow. For biofilters of 12 and 24 inches think, a wall taper of 9.6 degrees produced the least airflow variation at the end of one year as compared to a wall slope of 0 and 4.8 degrees. Improved media moisture distribution was achieved when the water soaker hose was placed on top of the media versus being suspended vertically through it. The value of this research leads to a more efficient vertical biofilter design configuration.