Empirical model of odor emission from deep-pit swine finishing barns to derive a standardized odor emission factor

Odor emission from swine housing is influenced by the herd characteristics and building environment. The following three specific factors were identified as inputs to a swine house odor emission model: indoor temperature, barn ventilation rate, and pig activity. Model input parameters were determined based on tests of four, identical, 1000-head, mechanically-ventilated swine finishing houses. Each building had two sidewall curtains, a curtain on the west end wall, five exhaust fans on the east end wall, four pit ventilation fans, and long-term manure storage beneath a fully slatted floor. Odor concentrations of 112 odor samples were determined using dynamic forced-choice olfactometry with four to six trained panelists. The emission model showed that the standard live mass specific odor emission factor was 48 OU s−1 per 500 kg live mass or animal unit (AU), and it corresponded to an indoor temperature of T0 = 20 °C, a ventilation rate of V0 = 200 m3 h−1 (55.6 × 10−3 m3 s−1) per pig (maximum capacity for summer time), and the daily mean animal activity. The rate of odor emission from a swine finishing house can be calculated based on these parameters coupled with the number of animals, the mean live mass, and the standard live mass specific odor emission factor. Using this process-based odor emission model, the odor emission estimation and therefore the input for odor dispersion models can be improved to obtain more reliable estimates of separation distance for siting future pig farms.