Progress 03/01/09 to 02/28/13
Outputs
Target Audience: Air quality scientists, poultry growers and integrator companies, state agencies, middle school students and other stakeholders. Changes/Problems: The project objectives were modified based on the results of experiments done in 2009. We found that the water curtain scrubber was not effective in removing ammonia from the exhaust air. Therefore, the proposed mitigation system was modified as a contained biofilter system. Various empty bed residence times were evaluated in their effect on ammonia removal efficiency and nitrous oxide generation rates. It was found that higher amount of nitrous oxide was generated when higher amount of ammonia was removed from the exhaust air stream. Further investigation is warranted to understand the interaction of the nitrogen transformation during biofiltration process. What opportunities for training and professional development has the project provided? The project team conducted a service project in collaborating with a science teacher at a local middle school in fall 2011. The concept of employing biofilter in removing ammonia from chicken house air was demonstrated using household ammonia cleaner, bathroom wash water, pH meters, etc. 100 students and one science teacher participated in the service project and were exposed to an introduction of air pollution, agriculture, engineering, etc. How have the results been disseminated to communities of interest? Biofilter for removing ammonia from ventilation air on a poultry farm was demonstrated at a field day event at the Applied Broiler Research Farm of University of Arkansas in October 2011. More than 100 poultry producers and company personnel participated the event, toured the on-site biofilter set up with poster display, and learned about the biofilter applications. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
The initial proposed open curtain water scrubber system was ineffective in removing ammonia from the exhaust air of a poultry house (< 10%). As a result, the open bed biofilter design had to be modified, with a contained biofilter system evaluated instead. By maintaining a preferred range of biofilter moisture contents, residence times of air through biofilter beds varied between 8 to 40 sec. Ammonia removal and simultaneous nitrous oxide gas generation of the biofilter were monitored. Complex interaction of nitrogen transformation of the biofilter existed and should be further investigated in order to utilize the biofilter system for ammonia emission mitigation and minimize greenhouse gas emissions.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2010
Citation:
Post, J. P., S. G. Bajwa, Y. Liang, T. A. Costello. 2010. A COMPARISON OF PARTICULATE MATTER CONCENTRATION MEASURED BY TEOM AND DUSTTRAK. International Symposium on Air Quality and Manure Management for Agriculture. 13-16 September 2010 Dallas Texas. ASABE
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Progress 03/01/11 to 02/28/12
Outputs
OUTPUTS: Six lab-scale biofilters were tested for over one year to evaluate their effectiveness in scrubbing ammonia from ammonia-laden air. The six biofilters started with slightly different media of 3 different C:N ratios of 30, 40 and 50, and two different column length of 1 m and 1.5 m respectively. The biofilter media contained different proportions of mulch, wood shavings, zeolite, char ash and poultry litter. Air containing 10-25 ppm of ammonia was passed through the media at 5 LPM for 5 h a day during 5 days of a week. With the incoming air with 10-25 ppm ammonia, all biofilter were consistently able to remove 99% of the ammonia from the air once the biofilter function was stabilized. The ammonia removal rate showed some dependence on the moisture content of the medium. The C:N ratio showed a very slow decline over the period of data collection. Correspondingly, the N in the medium showed a slow increase over the period of data collection. The particle size distribution of the medium shifted to the finer particles with respect to time, indicating microbial degradation of organic material. Two field scale biofilters of 4x4x8 ft were built at the Applied Broiler Research Farm at Savoy. The filter media contained wood chips, mulch, zeolite and poultry litter to ensure a beginning C:N ratio of 50 since this ratio provided the most effectiveness during the lab-scale trial. The air from the commercial broiler houses was drawn with a 500/750 CFM pump and send through the filter media. The inlet air contained 10-50 ppm of ammonia depending on flock age, season and ventilation rate. These biofilters also showed similar trends to the lab-scale biofilter in that the initial ammonia removal rate varied from 35-99% depending during the stabilization period. PARTICIPANTS: One graduate student (Jacob Post) is involved in conducting this research along with three undergraduate students (Alvaro Claure, Chris Martindale, Iain Bailey). Co-PIs for the project include Yi Liang and Tom Costello, both from Biological & Agricultural Engineering, and Susan Watkins from Poultry Science. TARGET AUDIENCES: Air quality scientists, poultry growers and integrators, state agencies, extension specialists, and other stakeholders. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Biofilters are potential mechanisms to remove ammonia from commercial broiler facilities. Although they may not be appropriate to treat all the exhaust air coming out of poultry houses because of the huge size of biofilters needed for such endeavors, smaller sized biofilter may be appropriate for reducing ammonia emissions from poultry houses to below critical levels. Also, biofilters have the potential benefits of acting as a source of heat and reducing the ventilation requirements during winter time. Moisture content of the biofilter media and retention time are critical factors that affect ammonia removal rate. Therefore, biofilters need to be carefully designed and operated to ensure the highest efficiency.
Publications
- No publications reported this period
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Progress 03/01/10 to 02/28/11
Outputs
OUTPUTS: A lab experiment was conducted to characterize the ammonia scrubbing ability of biofilters, and how various factors such as different filter media, residence time and moisture content would impact ammonia removal from the air. Six lab-scale vertical biofilters were built from 8" PVC pipes. The treatment variables included two residence times determined by the height (1 m and 1.5 m) of the biofilter, and three different filter media that resulted in starting C:N ratios of 30, 40 and 50 respectively. Based on literature review, a gravimetric moisture content of 40-60% was deemed appropriate for the filter media. Air containing ammonia at 10-25 ppm were passed through the 6 biofitlers. A small volume of air from the inlet and outlet of each of biofilter were passed through acid traps containing boric acid. The acid traps were calibrated for ammonia concentration with respect to pH. Acid traps were removed and analyzed after every 3 days, at which new acid traps were set up. Since our moisture sensors buried in the media did not work reliably, the biofilter media was taken out, mixed thoroughly, weighed, a sample was removed, and filled back in the filter holder once a week. Part of the sample taken was dried in the oven for measuring gravimetric moisture content, and then sieved for particle analysis. The remaining wet sample was send to the Agricultural Diagnostic Laboratory for analyzing total C and N in the media. PARTICIPANTS: One graduate student (Jacob Post) is involved in conducting this research and supervising the undergraduate students who are working in the project. Three undergraduate students (Alvero Claure, Joseph Chidiac, Iain Bailey) are getting trained in conducting the various aspects of this research including calibration of acid traps, pH meter, moisture meter, etc, particle analysis, construction of biofilter, monitoring the operations of the biofilter, data acquisition, etc. TARGET AUDIENCES: Air quality scientists, poultry growers and integrators, state agencies, extension specialists, and other stakeholders. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The very first batch of acid traps indicated an ammonia removal rate of less than 10% for biofilters with the C:N ratio of 30 at a media moisture content of 68%. The corresponding ammonia removal rates were 34.3% at a C:N ratio of 40 and moisture content of 58.7%, and 66% at a C:N ratio of 50 and moisture content of 65%. The 1.5 m biofilter had higher ammonia removal in the first 10 days of operation compared to the 1 m biofitler. A C:N ratio of 50 showed the higher ammonia removal at the beginning. After approximately 4 weeks of running the biofilter, there was no difference in ammonia removal between the two higher C:N ratios, both groups resulted in over 99% of ammonia removal. However, the biofilters with lower C:N ratio of 30 had shown significantly lower ammonia removal in the first two weeks, and the highest ammonia removal rate observed for these biofilters was slightly over 97%. Also, filter moisture content may have influenced how fast the microbial population was able to establish and remove ammonia from the incoming air. Our laboratory study indicates that the biofilter with higher C:N ratios of 40-50 were faster in establishing a steady state removal of ammonia.
Publications
- No publications reported this period
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Progress 03/01/09 to 02/28/10
Outputs
OUTPUTS: A wet scrubber prototype was built and evaluated for its efficiency in removing ammonia from the exhaust air of a commercial broiler house. This wet scrubber was installed at the hood of a tunnel fan such that 5 nozzles mounted at the rim of the hood sprayed water in to the exhaust air and another three nozzles sprayed water from the center of the hood outwards. All nozzles used had 110 degree spray angle. The scrubber was tested in between flocks when the house was decaked and tilled, with three different nozzles (Teejet XR11004VS, TT11015VP, TF-VS4) at three different pressures (165, 207 & 248 kPa) such that a range of droplet size and water application rates were obtained. The experiments were repeated 3 times resulting in 27 runs. During each run, the ammonia concentration of the exhaust air was monitored with an Innova sensor. The water used for scrubbing was collected from a 9 by 5 m area and analyzed for total ammoniacal nitrogen. The ammonia removal efficiency of the water scrubber was calculated as the ratio of amount of ammonia captured in water to the amount of ammonia in the exhaust air, expressed as a percentage. A similar experiment was also conducted while the chickens were in the house to evaluate the effectiveness of the scrubber for removing particulate matter (PM). The concentration of PM in the exhaust air was monitored with a TEOM device. The output water after scrubbing was collected, filtered, dried and weighed to measure the collected PM. The efficiency of the water scrubber was calculated as the ratio of the amount of PM captured by the water to the amount of PM in the exhaust air recorded by TEOM, expressed as a percentage. A third experiment was conducted to quantify the hydraulic residence time (HRT) of different biofilter media since this would be a key factor affecting the amount of ammonia removed by a biofilter. The HRT was calculated for different mixtures of wood shavings, mulch and chicken litter with C:N ratios of 56, 48, 40, and 32, using a procedure mentioned by Garzon-Zuniga et al. (2003). A clear acrylic column of 1.5 m long and 0.15 cm diameter was filled with a specific biofilter media. After packing the filter material, the column was filled with water to submerge all the material. The biofilter column was then drained and the water was collected at the bottom of the column. Weight of this water was measured to determine volume flow rate at 1, 2, 4, 16, 33, 89, 232, 282, and 1200 minutes. The porosity of a material was then calculated, which was used to calculate the HRT as (Vwc+Vwf-Vvg)/Q, where Vwc is the total volume of water collected at the end of experiment, Vwf is the volume of water remaining in the filter media after the experiment, Vvg is the volume of pore space occupied by gas, and Q the flow rate of water through the filter media. PARTICIPANTS: Other than the project directors, two graduate students, Prathamesh Bandekar and Jacob Post worked in this project in 2009. TARGET AUDIENCES: Air quality scientists, poultry growers and integrators, state agencies, extension specialists, and other stakeholders. PROJECT MODIFICATIONS: The project objectives were modified slightly based on the results of experiments done in 2009. We found that the water scrubber was not very effective in removing ammonia from the exhaust air. Therefore, we have modified the proposed mitigation system from an open water curtain and biofilter working in series to a contained biofilter and water scrubber. In new design that we are proposing, plastic bags used for storing forage or silage will be used to contain the biofilter media. Water will be applied to biofilter media at an optimal rate to ensure water scrubbing and microbial activity. The objectives we are currently working on include: (1) Model ammonia diffusion and immobilization in a bag biofilter system as a plug flow reactor so as to develop design guidelines. (2) Build and evaluate this bag biofilter. The bag biofitler is expected to run off a dedicated fan mounted on a tunnel-ventilated broiler house. The scrubbed air will be recirculated back to the house such that the birds will benefit from the mitigation system. This system will also avoid issues of rodents or birds getting into the biofilter. In addition to wood shavings and mulch, we are also looking into char ash as a potential filter medium with a high C:N ratio.
Impacts
The average concentration of ammonia in the house varied from 7.25 ppm to 33.9 pmm during the experiment with an average fan flow rate of 41,221 cu.m/hr. The average mass of ammonia released from the house during the experiment varied from 54 g/hr to 976 g/hr. Approximately, 71-98% of the sprayed water was recovered from the sampling area of 9 m by 5 m in front of the fan. The ammonia removal efficiency of all treatments were below 10%, mainly due to the limited contact time the water had with exhaust air, which was 0.5 s. The type of nozzle and operating pressure did not affect the ammonia removal efficiency. The water curtain performance was superior in removing particulate matter compared to ammonia. On average, the PM removal efficiency varied from 40-94% under different conditions of PM concentrations in the exhaust air, water pressure and nozzle. The performance of the water curtain indicates that it may be an effective method for removing particulate matter, but not very effective in removing ammonia from the exhaust air coming from broiler houses. The HRT of 1.5 m long filter packs varied from 9.4 to 11.3 min. As the C:N ratio increased, HRT decreased. This negative relationship was mainly caused by the fact that the filter media components with higher N content (such as poultry litter) also had finer particle size compared to the coarser wood shavings with low N content.
Publications
- No publications reported this period
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