Temporal Variations in Gas and Odor Emissions from a Dairy Manure Storage Pond

摘要

As dairy production evolves towards larger and more concentrated operations, air and water quality on and around dairy farms is becoming a significant concern. It is necessary to understand air emission temporal variations for development and implementation of effective abatement technologies and management practices. The objectives of this study were to understand temporal variations in H_2S, NH_3, and odor emissions from a dairy manure storage pond, the effects of manure characteristics and environmental conditions on gas emissions, and gas management need of dairy manure storage ponds. One representative Ohio dairy farm with a 675-cow free-stall barn and one outside earthen manure storage pond was selected as the experimental farm. Monthly measurements of H2S, ammonia, and odor emissions from the dairy manure storage pond were conducted using a convective flux chamber and gas analyzers. Surface manure was sampled for manure characteristics analysis. Manure temperature and weather conditions weremeasured. The data was analyzed using general statistical description, correlation, and regression analysis. The results showed there were large temporal variations in NH_3, H2S, and odor emissions among months of the year. The daily mean NH_3, H_2S, and odor emission rates ranged from 5.7 to 174.8 ug s~(-1) m~(-2), 0.1 to 4.6 ug s~(-1) m~(-2), and 0 to 10.34 OU s~(-1) m~(-2), respectively. The daily H_2S emission was not a concern relative to the EPCRA and CERCLA's 100 lb d~(-1) reporting requirementfor NH_3 and H_2S. However, NH_3 emission from the 650-700 dairy operation exceeded 100 lb d~(-1) in warmer months. Daytime NH_3 emission variations were small and within about 10-20% of the mean. However, the daytime H_2S emission variations were significant. Odor andNH_3 emission was strongly correlated with the ambient air temperatures. Higher ambient temperature resulted in higher odor and NH_3 emissions. However, H_2S emissions were not clearly associated with the ambient temperatures and fluctuated month by month without a clear statistical trend. Higher surface air velocities resulted in higher gas and odor emissions. However, the exact correlation relationship was not easily determined from the limited field studies.