Odor and Gas Release from Anaerobic Treatment Lagoons for Swine Manure

Odor and gas release from anaerobic lagoons for treating swine waste affect air quality in neighboring communities but rates of release are not well documented. A buoyant convective flux chamber (BCFC) was used to determine the effect of lagoon loading rate on measured odor and gas releases from two primary lagoons at a simulated wind speed of 1.0 m s −1 Concentrations of ammonia (NH 3 ), hydrogen sulfide (H 2 S), carbon dioxide (CO 2 ), sulfur dioxide (SO 2 ), and nitric oxide (NO) in 50‐L air samples were measured. A panel of human subjects, whose sensitivity was verified with a certified reference odorant, evaluated odor concentration, intensity, and hedonic tone. Geometric mean odor concentrations of BCFC inlet and outlet samples and of downwind berm samples were 168 ± 44 (mean ± 95% confidence interval), 262 ± 60, and 114 ± 38 OU E m −3 (OU E , European odor unit, equivalent to 123 μg n ‐butanol), respectively. The overall geometric mean odor release was 2.3 ± 1.5 OU E s −1 m −2 (1.5 ± 0.9 OU s −1 m −2 ). The live mass specific geometric mean odor release was 13.5 OU E s −1 AU −1 (animal unit = 500 kg live body mass). Overall mean NH 3 , H 2 S, CO 2 and SO 2 releases were 101 ± 24, 5.7 ± 2.0, 852 ± 307, and 0.5 ± 0.4 μg s −1 m −2 , respectively. Nitric oxide was not detected. Odor concentrations were directly proportional to H 2 S and CO 2 concentrations and odor intensity, and inversely proportional to hedonic tone and SO 2 concentration ( P < 0.05). Releases of NH 3 , H 2 S, and CO 2 were directly proportional ( P < 0.05) to volatile solids loading rate (VSLR).