Composting facilities are essential parts of most manure-belt (MB) poultry houses in the U.S., but their NH 3 concentrations and emission are not well understood. This may affect farm operation safety and limit the development of NH 3 mitigation and management strategies. The study aimed to quantify NH 3 concentrations and hen-specific emission rates (ER) at a commercial poultry manure composting facility and to understand their diurnal and seasonal
As dairy operations evolve towards larger, concentrated facilities, air quality on and around the dairy farms becomes a concern. Data on air quality in and around large dairy facilities are insufficient and therefore very much needed. In this study, preliminary data on air quality spatial distribution and temporal variations on two new large dairy facilities with naturally ventilated free stall barns and outside manure storage were collected. Concentration of hydrogen sulfide (H 2 S) and ammonia (NH 3) at 12 to 14 locations on each farm were measured in three seasons using portable gas analyzers. Odor samples were collected at odor sources, upwind and downwind locations. Dust was measured using a portable dust mass concentration meter. Gas levels inside the dairy buildings at one leeward location were continuously monitored for three days in two seasons. In addition, indoor and outdoor temperature, relative humidity, and air velocity were measured to determine effects of these parameters on air quality. The study found that manure storage ponds have the most effect on air quality during warm and hot seasons. Variations of air quality inside the dairy building were insignificant. Inside the dairy buildings, the average dust mass concentrations range from 0.9 to 1.5 mg m-3 ; ammonia 1.4 to 3 ppm, hydrogen sulfide 2 to 32 ppb; and odor concentration 90 to 140 OU m-3. However at the downwind berm of the manure storage ponds, odor concentration reached 1256 OU/m 3 during the hot weather months. Weather conditions also affected the outdoor dispersion of air emissions. Most of the time, gas levels at 152 m downwind of the barn and manure storage were similar to upwind levels, but on hot and windy days these levels reached a point high enough to raise concerns. Inside the building, the hydrogen sulfide concentrations were not significantly different from hour to hour within a day or from day to day within a season. Although daily variation of mean ammonia concentrations were significantly different, hourly mean ammonia concentrations were not significantly different between morning hours and afternoon hours within any given day.
Significant ammonia emissions from animal facilities need to be controlled due to its negative impacts on human health and the environment. The use of acid spray scrubber is promising, as it simultaneously mitigates and recovers ammonia emission for fertilizer. Its low pressure drop contribution on axial fans makes it applicable on US farms. This study develops a full-scale acid spray scrubber to recover ammonia emissions from commercial poultry facilities and produce nitrogen fertilizer. The scrubber performance and economic feasibility were evaluated at a commercial poultry manure composting facility that released ammonia from exhaust fans with concentrations of 66-278 ppmv and total emission rate of 96,143 kg yr(-1). The scrubber consisted of 15 spray scrubber modules, each equipped with three full-cone nozzles that used dilute sulphuric acid as the medium. Each nozzle was operated at 0.59 MPa with a droplet size of 113 μm and liquid flow rate of 1.8 L min(-1). The scrubber was installed with a 1.3-m exhaust fan and field tested in four seasons. Results showed that the scrubber achieved high NH3 removal efficiencies (71-81%) and low pressure drop (<25 Pa). Estimated water and acid losses are 0.9 and 0.04 ml m(-3) air treated, respectively. Power consumption rate was between 89.48 and 107.48 kWh d(-1). The scrubber effluents containing 22-36% (m/v) ammonium sulphate are comparable to the commercial-grade nitrogen fertilizer. Preliminary economic analysis indicated that the break-even time is one year. This study demonstrates that acid spray scrubbers can economically and effectively recover NH3 from animal facilities for fertilizer.
The anaerobic activities in swine slurry storage and treatment generate biogas containing gaseous ammonia component which is a chemical agent that can cause adverse environmental impacts when released to the atmosphere. The aim of this pilot plant study was to remove ammonia from biogas generated in a covered lagoon, using a sulfuric acid wet scrubber. The data showed that, on average, the biogas contained 43.7 ppm of ammonia and its concentration was found to be exponentially related to the air temperature inside the lagoon. When the air temperature rose to 35°C and the biogas ammonia concentration reached 90 ppm, the mass transfer of ammonia/ammonium from the deeper liquid body to the interface between the air and liquid became a limiting factor. The biogas velocity was critical in affecting ammonia removal efficiency of the wet scrubber. A biogas flow velocity of 8 to 12 mm s(-1) was recommended to achieve a removal efficiency of greater than 60%. Stepwise regression revealed that the biogas velocity and air temperature, not the inlet ammonia concentration in biogas, affected the ammonia removal efficiency. Overall, when 73 g L(-1) (or 0.75 M) sulfuric acid solution was used as the scrubber solution, removal efficiencies varied from 0% to 100% with an average of 55% over a 40-d measurement period. Mass balance calculation based on ammonium-nitrogen concentration in final scrubber liquid showed that about 21.3 g of ammonia was collected from a total volume of 1169 m(3) of biogas, while the scrubber solution should still maintain its ammonia absorbing ability until its concentration reaches up to 1 M. These results showed promising use of sulfuric acid wet scrubber for ammonia removal in the digester biogas.
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