Use of Amendments in Pits and Lagoons for Reducing Ammonia, Odor and Sludge1

Background Anaerobic (absence of air or oxygen) bacteria play an important role in breaking down the hog waste (urine, feces, wasted feed, etc.) into simpler organic and inorganic compounds in the pits and lagoons. However, this also results in the production of many organic gases, also called volatile organic compounds (VOCs) as well as inorganic gases (e.g., ammonia, hydrogen sulfide). Many of these gases, individually or in combination with other gases, produce objectionable odors. Schiffman et al. (2001a) identified 331 VOCs in hog waste that contribute to odors. As the population ofNC grows and subdivisions are being built closer to hog farms, odors can result in friction between hog producers and homeowners. Some manure gases can also affect the health of the hogs and workers at high concentrations. Jones et al. (1997) showed that ammonia concentrations in the 10 to 15 ppm range reduced resistance to infection in hogs. Ammonia has been identified as an air pollutant of major importance at the large scale as it contributes to formation of very fine particulate matter that can cause (and increase) respiratory diseases and haze (NRC, 2003). Hence, the US EPA is considering regulating emissions of not just ammonia but also other air pollutants from animal agriculture under the Clean Air Act as well as other laws. Dietary manipulation (e.g. , reducing crude protein), technology (e.g., spraying oil in the houses) , management (e.g. , regular wash-down of pens), or amendments can be used to reduce production of odorous gases in hog facilities . Amendments can also reduce sludge levels in the lagoon thereby requiring sludge removal at greater intervals. This paper focuses on amendments (additives) for use in hog house shallow pits and lagoons because they can improve productivity and air quality and reduce sludge levels in lagoons.