Comparative Assessment of Ammonia Emissions from Potential Environmentally Superior Technologies for Swine Facilities

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Title: Comparative Assessment of Ammonia Emissions from Potential Environmentally Superior Technologies for Swine Facilities
Author: Semunegus, Hilawe
Advisors: Dr. Viney P. Aneja, Committee Co-Chair
Dr. Sethu Raman, Committee Member
Dr. John J. Bates, Committee Member
Dr. S. Pal Arya, Committee Chair
Abstract: Globally, domestic animal waste contributes nearly half of the total tropospheric ammonia (NH3) emitted into the atmosphere. In North Carolina, swine waste from agricultural operations represents 47% of the total ammonia emissions and 21% of the state's nitrogen budget. Due to the short residence time of NH3 (1-5 days) in the atmosphere, deposition occurs close to emission sources. Ammonia that does not deposit quickly combines with acidic species such as sulfuric acid, nitric acid, and hydrochloric acid to form ammonium aerosols. Ammonium aerosols travel farther from emission sources due to their lower deposition velocity leading to longer residence time (1-15 days) compared to gaseous ammonia. Detrimental effects of high concentrations and dry and wet depositions of reduced N species include harmful algal blooms, nitrogen enrichment, and eutrophication in aquatic ecosystems, soil acidification, and respiratory damage due to exposure of fine particulate matter (PM 2.5) formation, nitrogen saturation of forest soil, odor emanation, and visibility degradation. In response to perceived adverse environmental impacts of the nearly 10 million hogs residing in North Carolina, alternative waste treatment methods were evaluated that could potentially reduce substantial emissions of ammonia. These are being evaluated by the OPEN Project Team. This study was a part of that evaluation, especially focusing on the ammonia emissions from two potential environmentally superior technologies (ESTs). Between April 2002 and February 2003, continuous NH3 flux measurements were conducted over 2-week periods from two potential ESTs during two different (warm and cold) seasons and compared with two conventional Lagoon and Spray Technology (LST) facilities, which were also sampled during different seasons. The two alternative technologies are (1) The Covered In-Ground Ambient Digester Technology and (2) The Constructed Wetlands/Solid Separator Technology. Using the dynamic flow-through chamber system, ammonia flux measurements were determined, along with measurements of meteorological parameters such as wind speed and direction, air temperature, relative humidity, and solar radiation from a 10 m tower at all the EST and LST sites. For LST sites, the average ammonia fluxes for the storage ponds were 2,385 Āg NH3-N/m2/min for Stokes Farm and 1,657 μg NH3-N/m2/min for Moore Farm during the fall season measurement campaigns. For winter season measurement campaigns, average ammonia flux measurements were 153 and 325 Āg NH3-N/m2/min for the storage ponds at Stokes and Moore farms, respectively. For the April and November 2002 measurement campaigns at Barham Farm (EST), respectively, the average ammonia fluxes from the liquid waste storage ponds were 1,169 Āg NH3-N/m2/min and 352 Āg NH3-N/m2/min. At Howard Farm (EST), average measured ammonia fluxes were 790 Āg NH3-N/m2/min and 243 Āg NH3-N/m2/min during the June and December 2002 field campaigns. Using the mass balance method, NH3-N emissions from conventional LST or baseline sites were compared with those from ESTs. Ammonia emissions from different components such as liquid waste storage ponds, hog barns, and spray fields were also evaluated. To predict baseline NH3-N emissions during the EST measurement periods, lagoon temperature (TL) and air temperature — lagoon temperature difference (D) were inserted into an observational statistical model, developed from all baseline measurements. The observational model equation for average lagoon emissions at baseline sites is as follows, Log10(Area*flux/ton) = 3.8655 + 0.0449*TL — 0.05946*D where TL and D are in oC and Area*flux/ton represents the NH3-N emissions from the lagoon per 1000 kg of live animal weight, expressed in units of Āg NH3-N/1000 kg-LAW/min. Emissions of NH3-N normalized by the nitrogen excretion rate show that the Constructed Wetlands/Solid Separator Technology was not effective at all in reducing nitrogen emissions compared to the conventional Lagoon and Spray Technology. The Covered In-Ground Ambient Digester Technology was somewhat effective in reducing NH3-N emissions compared to conventional Lagoon and Spray Technology, especially when the former attained steady-state.
Date: 2003-09-24
Degree: MS
Discipline: Marine, Earth and Atmospheric Sciences

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