Browsing by Subject "ammonia"
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Item Back-calculating emission rates for ammonia and particulate matter from area sources using dispersion modeling(Texas A&M University, 2004-11-15) Price, Jacqueline ElaineEngineering directly impacts current and future regulatory policy decisions. The foundation of air pollution control and air pollution dispersion modeling lies in the math, chemistry, and physics of the environment. Therefore, regulatory decision making must rely upon sound science and engineering as the core of appropriate policy making (objective analysis in lieu of subjective opinion). This research evaluated particulate matter and ammonia concentration data as well as two modeling methods, a backward Lagrangian stochastic model and a Gaussian plume dispersion model. This analysis assessed the uncertainty surrounding each sampling procedure in order to gain a better understanding of the uncertainty in the final emission rate calculation (a basis for federal regulation), and it assessed the differences between emission rates generated using two different dispersion models. First, this research evaluated the uncertainty encompassing the gravimetric sampling of particulate matter and the passive ammonia sampling technique at an animal feeding operation. Future research will be to further determine the wind velocity profile as well as determining the vertical temperature gradient during the modeling time period. This information will help quantify the uncertainty of the meteorological model inputs into the dispersion model, which will aid in understanding the propagated uncertainty in the dispersion modeling outputs. Next, an evaluation of the emission rates generated by both the Industrial Source Complex (Gaussian) model and the WindTrax (backward-Lagrangian stochastic) model revealed that the calculated emission concentrations from each model using the average emission rate generated by the model are extremely close in value. However, the average emission rates calculated by the models vary by a factor of 10. This is extremely troubling. In conclusion, current and future sources are regulated based on emission rate data from previous time periods. Emission factors are published for regulation of various sources, and these emission factors are derived based upon back-calculated model emission rates and site management practices. Thus, this factor of 10 ratio in the emission rates could prove troubling in terms of regulation if the model that the emission rate is back-calculated from is not used as the model to predict a future downwind pollutant concentration.Item Chemical and Physical Properties of Atmospheric Aerosols (a) A Case Study in the Unique Properties of Agricultural Aerosols (b) The Role of Chemical Composition in Ice Nucleation during the Arctic Spring(2011-08-08) Moon, Seong-GiThis study focuses on the analysis of atmospheric particles sampled from two different field campaigns: the field study at a cattle feeding facility in the summer from 2005 to 2008 and the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in 2008. A ground site field study at a representative large cattle feeding facility in the Texas Panhandle was conducted to characterize the particle size distributions, hygroscopicity, and chemical composition of agricultural aerosols. Here, a first comprehensive dataset is reported for these physical and chemical properties of agricultural aerosols appropriate for use in a site-specific emission inventory. The emission rate and transport of the aerosols are also discussed. In addition, mixing ratios of total and gaseous ammonia were measured at the same field in 2007 and 2008. Measurements such as these provide a means to determine whether the fugitive dust emitted from a typical large feedlot represents a health concern for employees of the feeding operation and the nearby community. Detailed chemical composition of aircraft-sampled particles collected during ISDAC was studied. Filter samples were collected under a variety of conditions in and out of mixed phase and ice clouds in the Arctic. Specifically, particles were sampled from a mixed-phase cloud during a period of observed high concentrations of ice nuclei (IN), a biomass plume, and under relatively clean ambient conditions. Composition of particles was studied on a particle-by-particle basis using several microspectroscopy techniques. Based on the elemental composition analysis, more magnesium was found in Arctic cloud residues relative to ambient air. Likewise, based on the carbon speciation analysis, high IN samples contained coated inorganics, carbonate, and black or brown carbon particles. In the samples collected during a flight through a biomass burning plume, water-soluble organic carbon was the dominant overall composition. Due to their hygroscopic nature, these organics may preferably act as cloud condensation nuclei (CCN) rather than IN. Other ambient samples contained relatively higher fractions of organic and inorganic mixtures and less purely water-soluble organics than found in the biomass particles. The most likely source of inorganics would be sea salt. When present, sea salt may further enhance ice nucleation.Item Design and performance of an ammonia measurement system(Texas A&M University, 2007-04-25) Boriack, Cale NolanAmmonia emissions from animal feeding operations (AFOs) have recently come under increased scrutiny. The US Environmental Protection Agency (EPA) has come under increased pressure from special interest groups to regulate ammonia. Regulation of ammonia is very difficult because every facility has different manure management practices. Different management practices lead to different emissions for every facility. Researchers have been tasked by industry to find best management practices to reduce emissions. The task cannot be completed without equipment that can efficiently and accurately compare emissions. To complete this task, a measurement system was developed and performance tested to measure ammonia. Performance tests included uncertainty analysis, system response, and adsorption kinetics. A measurement system was designed for measurement of gaseous emissions from ground level area sources (GLAS) in order to sample multiple receptors with a single sensor. This multiplexer may be used in both local and remote measurement systems to increase the sampling rate of gaseous emissions. The increased data collection capacity with the multiplexer allows for nearly three times as many samples to be taken in the same amount of time while using the same protocol for sampling. System response analysis was performed on an ammonia analyzer, a hydrogen sulfide analyzer, and tubing used with flux chamber measurement. System responses were measured and evaluated using transfer functions. The system responses for the analyzers were found to be first order with delay in auto mode. The tubing response was found to be a first order response with delay. Uncertainty analysis was performed on an ammonia sampling and analyzing system. The system included an analyzer, mass flow controllers, calibration gases, and analog outputs. The standard uncertainty was found to be 443 ppb when measuring a 16 ppm ammonia stream with a 20 ppm span. A laboratory study dealing with the adsorption kinetics of ammonia on a flux chamber was performed to determine if adsorption onto the chamber walls was significant. The study found that the adsorption would not significantly change the concentration of the output flow 30 minutes after a clean chamber was exposed to ammonia concentrations for concentrations above 2.5 ppm.Item Development of an ammonia emission protocol and preliminary emission factor for a central Texas dairy(Texas A&M University, 2004-09-30) Rose, Adam JosephA protocol was developed to measure ammonia emission concentrations from dairies using an isolation flux chamber. A hybrid dairy in Comanche county, Texas, was measured for one week each during August 2002 and January 2003. Sixty total ammonia samples were taken from the free stall barn, open lot, mixing tank, separated solids, compost, and two lagoons using the developed protocol. The ammonia concentration measurements were made using a chemiluminescence analyzer located inside a mobile laboratory. From the emission concentrations recorded, it was estimated that 9.68 metric tons of ammonia were produced from this dairy per year. An emission factor of 13.34 ? 28.80 kilograms per day per thousand head of cattle (kg/day/1000 head) was estimated for this dairy (?95% confidence intervals) during summer conditions. For winter conditions the emission factor was 12.05 ? 12.89 kg/day/1000 head. The 11% difference of the emission factors from summer to winter conditions was predominantly from the change in ambient and control volume temperatures (a mean difference of approximately 25 degrees Celsius), differences in source temperatures, and seasonal variability in husbandry. The adsorption of ammonia onto different polymer tubing used in pollutant stream conveyance was researched for possible systematic losses. Teflon and low density polyethylene (LDPE) were tested for ammonia losses with treatments of: temperature, length, and inlet concentration. Inlet concentration and temperature were significant factors used to describe ammonia adsorption for Teflon, whereas LDPE was also affected by tubing length. These factors were used to create a model to correct the summer dairy measurements for ammonia losses, resulting in an emission factor increase of 8.3% over the original value obtained from the flux chamber. A nitrogen mass balance was performed to estimate the amount of nitrogen available for ammonia formation as excreted - 177.5 kilograms per year per animal (wet basis). The amount of ammonia excreted per year was also estimated to be 26.63 kilograms per year. The measured ammonia emitted from the dairy was five times less than the ammonia excreted and thirty-six times less than the total nitrogen excreted.Item Effects of Microbial Litter Amendments on Broiler Performance, Litter Quality and Ammonia Production(2011-02-22) Hinkle, MatthewThe reuse of litter in broiler production can lead to litter pathogen buildup and high levels of ammonia in broiler housing, thus resulting in poor broiler performance. This study evaluated the effects of two microbial litter amendments on litter characteristics, ammonia production and broiler performance. Experiment one, consisting of three trials, utilized eight pens approximately 3 x 3.2 m (10 x 10.5 ft) to rear broilers to 49 d of age. Experiment two, consisting of one trial, utilized twelve 1.8 x 3.7 m (6 x 12 ft) pens to rear broilers to 42 d of age. Used litter was obtained from separate commercial broiler farms for each experiment and placed into the pens at an average depth of 11 cm (4.3 in). Feed consumption and mortality were recorded for each pen for each trial. Ammonia production was measured by placing an enclosed chamber over the litter and measuring the headspace ammonia concentration after 20 minutes for both experiments. Experiment one also utilized a two minute ammonia flux technique. Ammonia measurements were taken at the time of litter treatment, at chick placement, and once per week for the remainder of the grow-out. Litter samples were collected at the same time and location as ammonia measurements. At the end of all trials, caked litter was removed from each pen, weighed and sampled. Litter and cake samples were analyzed for total aerobic and anaerobic microbial counts in experiment 1. Experiment 2 analyzed aerobic litter samples only. Paw scores were also recorded at the end of each trial for all birds using a 3-point scale. Data was subjected to ANOVA using the GLM procedure with means deemed significantly different at P < 0.05. Statistical differences were seen sparingly in different parameters in both experiments; however these differences were random in their distribution and showed no trend. Final results indicated that the microbial litter amendments had no effect on broiler performance, litter characteristics or ammonia production.Item Quantification of litter production and the fate of nitrogen in commercial broiler production systems(Texas A&M University, 2005-11-01) Coufal, Craig DanielThe environmental impacts of broiler production have recently gained considerable public attention due to concerns regarding the amount of ammonia (NH3) released into the atmosphere from poultry facilities. Sound scientific data are needed to accurately estimate the production of manure waste products and gaseous emissions. This research project was undertaken to quantify nitrogen (N) loss through air emissions from a broiler grow-out facility over 18 consecutive flocks using the mass balance method. Measurement of litter and caked litter (cake) mass at the end of each flock allowed for the calculation of litter and cake production rates for broilers reared on recycled rice hull litter. Nutrient (nitrogen, phosphorus, and potassium) content of all litter materials was also measured. Broilers were reared in a research facility under simulated commercial conditions. All input materials (birds, feed, and litter) used in this study were obtained directly from a commercial broiler integrator to assure applicability to the broiler industry. The litter management technique of ??top-dressing?? was also investigated to determine its effects on N emissions and litter and cake production rates. Nitrogen emissions, litter and cake production rates, and nutrient density of litter materials were found to vary significantly between flocks reared at different times of the year. Nitrogen emissions were significantly greater for summer flocks than winter flocks. Average N loss over all 18 flocks was 11.07 g N/kg of marketed broiler (g N/kg). Nitrogen partitioning as a percentage of inputs averaged 15.29, 6.84, 55.52, 1.27, and 21.08% for litter, caked litter, broiler carcasses, mortalities and nitrogen loss, respectively, over all 18 flocks. Litter and cake production was lower in the summer compared to winter. Average litter, cake, and all litter (litter + cake) production was 153.3, 74.8, and 228.2 g of dry litter material/kg of marketed broiler. Litter and cake phosphorus and potassium content was elevated during summer flocks, while litter material N content decreased in summer flocks. Therefore, season of the year is an important factor that scientists and broiler producers must take into account when performing measurements and calculations, sampling litter materials and air emissions, and developing nutrient management plans.Item Selective Catalytic Reduction (SCR) of nitric oxide with ammonia using Cu-ZSM-5 and Va-based honeycomb monolith catalysts: effect of H2 pretreatment, NH3-to-NO ratio, O2, and space velocity(Texas A&M University, 2004-09-30) Gupta, SaurabhIn this work, the steady-state performance of zeolite-based (Cu-ZSM-5) and vanadium-based honeycomb monolith catalysts was investigated in the selective catalytic reduction process (SCR) for NO removal using NH3. The aim was to delineate the effect of various parameters including pretreatment of the catalyst sample with H2, NH3-to-NO ratio, inlet oxygen concentration, and space velocity. The concentrations of the species (e.g. NO, NH3, and others) were determined using a Fourier Transform Infrared (FTIR) spectrometer. The temperature was varied from ambient (25 C) to 500 C. The investigation showed that all of the above parameters (except pre-treatment with H2) significantly affected the peak NO reduction, the temperature at which peak NO reduction occurred, and residual ammonia left at higher temperatures (also known as 'NH3 slip'). Depending upon the particular values of the parameters, a peak NO reduction of around 90% was obtained for both the catalysts. However, an accompanied generation of N2O and NO2 species was observed as well, being much higher for the vanadium-based catalyst than for the Cu-ZSM-5 catalyst. For both catalysts, the peak NO reduction decreased with an increase in space velocity, and did not change significantly with an increase in oxygen concentration. The temperatures at which peak NO reduction and complete NH3 removal occurred increased with an increase in space velocity but decreased with an increase in oxygen concentration. The presence of more ammonia at the inlet (i.e. higher NH3-to-NO ratio) improved the peak NO reduction but simultaneously resulted in an increase in residual ammonia. Pretreatment of the catalyst sample with H2 (performed only for the Cu-ZSM-5 catalyst) did not produce any perceivable difference in any of the results for the conditions of these experiments.