Engineered Windbreak Wall-Vegetative Strip System to Reduce Pollutant and Odor Emissions from Mechanically-Ventilated Broiler and Swine Barns

Livestock farms are major sources of ammonia and odor and they also emit hydrogen sulfide, particulate matter (PM) and greenhouse gases that affect the environment, public health, visibility and quality-of-life of neighbors. The U.S. EPA may regulate livestock barn emissions under the Clean Air Act and it is paying particular attention to ammonia because it is released in large amounts and it is a precursor of fine PM (i.e., PM2.5) which impacts public health and visibility. Local ordinances and nuisance complaints could also force livestock producers to reduce odor emissions. Improving management practices can improve air quality marginally but to reduce pollutant and odor emissions from barns substantially and consistently many farms may require exhaust air treatment to comply with the Clean Air Act. While conventional exhaust air treatment technologies are effective, they are very expensive and they choke the ventilation system. One promising method is the use of natural windbreaks (trees and shrubs) that can reduce odors without affecting the ventilation system. But windbreaks require maintenance, have large footprints and cannot be placed close to the fans where they would be more effective. This project will develop a low-cost, engineered windbreak wall – vegetative strip system. Computational fluid dynamics modeling will be used to design the system, including, vegetation height and density and wall features (e.g., height, angled or vertical) to maximize effectiveness by balancing pollutant removal, dilution to reduce odors and acceptable back pressure on the fans. Two systems will be installed to treat the exhaust gases of tunnel-ventilated livestock barns (roaster and swine) and monitored over two years. Inlet and outlet gas, PM and odor concentrations will be measured to evaluate treatment effect. Concentrations of pollutants and their fates will be determined using soil and plant analyses and compared with control areas. Finally, cost-effectiveness of the system will be determined based on reductions in $/kg of the pollutants.