Odor emission in lagoons is due to the production of odorous compounds, their emission to the atmosphere, and their transportation to the receptors. The keys of odor control of lagoons are prevention of the production, the emission, and/or the transportation of the odorous compounds. Odor is considered as a result of the microbial activities and caused by the production of the odorous volatile compounds such as volatile fatty acids, phenols, ammonia, volatile amines, hydrogen sulfide (the major one), and volatile sulfur-containing compounds, which are intermediate or end products in organic matter degradation during anaerobic processes.