Iowa Concentrated Animal Feeding Operations Air Quality Study-Executive Summary

Emissions odors, gases, and dust from livestock production facilities arise primarily from three sources; buildings, manure storages, and land application (1). Emissions from buildings and storages form a baseline emission level. Eliminating emissions from one of the sources will likely not eliminate emissions entirely. Control technologies often address only one of the three sources. Many of the technologies reduce emissions; none eliminate them. Emissions from buildings can be reduced by inhibiting contaminant generation, or by treating the air as it leaves the building. Frequent manure removal is one of the best ways of reducing contaminant generation within the building. Frequent removal requires outdoor storage. Other methods include the use of bedding, oil sprinkling, chemical additives, and diet manipulation. Treating the air leaving a building can be done with washing walls or biofilters. Natural or manmade windbreak walls may be beneficial. There are four types of storages; deep pits, outdoor slurry storage, anaerobic lagoons, and solid stacks. Outdoor storages are the most apparent source of odors. Controls include permeable and impermeable, natural and synthetic covers. They have been shown to be effective when managed properly. Solids separation has not been proven effective to reduce odors. Proper aeration will eliminate odors from outdoor storages, but is expensive in a liquid system. Composting works well for solid manure. Anaerobic digesters reduce odors, but are also not economically feasible. Manure additives are generally not reliable. Emission control during land application is best done by direct injection.