Many industrial odors associated with food production are the result of sulfur compounds or ammonia compounds. Hydrogen sulfide, sulfur dioxide, thioethers, and mercaptans are examples of sulfur compounds, released from sulfur containing components, that have very disagreeable odors. Ammonia and the oxides of nitrogen are examples of odor causing agents released by the degradation of complex ammonium and nitrogen compounds.
Air scrubbers in the exhaust stacks are often the first interventions to treat odor emitted from industrial plants. These are water sprays used to wash out any water soluble components in the air stream and add them to the waste stream from the plant where it can be treated and disposed of in an environmentally acceptable way. Chemicals can be added to this water stream to further treat the odor stream. Sulfur compounds are easily oxidized to a state that is odorless so oxidation chemistry is often used to neutralize sulfur odors. Ammonia is a volatile gas so reactions that convert the ammonia to a nonvolatile ammonium compound are frequently employed to eliminate that odor. Other options exist, such as the addition of an odoractant to change the apparent scent of the odors being emitted. For weaker odors it is possible to mask them with a stronger albeit more pleasant odor to hide the more offensive one. It is also possible to dilute odors to make them less offensive by increasing the air volume in the stream and increasing the discharge height of the stacks.
In an effort to be good neighbors, most companies make some effort to control obnoxious odors that result in complaints from the surrounding community.