AIR EMISSIONS FROM TWO SWINE FINISHING BUILDING WITH FLUSHING: AMMONIA CHARACTERISTICS

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1 This is not a peer-reviewed article. Livestock Environment VII, Proceedings of the Seventh International Symposium, 18-2 May 25 (Beijing, China) Publication Date 18 May 25, ASAE Publication Number 71P25. Ed. T. Brown-Brandl. Copyright 25 American Society of Agricultural Engineers, St. Joseph, Michigan USA. AIR EMISSIONS FROM TWO SWINE FINISHING BUILDING WITH FLUSHING: AMMONIA CHARACTERISTICS Albert J. Heber, Pei-Chun Tao, Ji-Qin Ni, Teng T. Lim, and Amy M. Schmidt ABSTRACT The goal of this 11-month study was to evaluate the characteristics of ammonia (NH 3 ) emission during a test of 1) soybean oil sprinkling (SOS), 2) misting of essential oils, and 3) misting of essential oils and water. Measurements were recorded every 6 s from August 22 to July 23 at two tunnel-ventilated swine finishing barns that were flushed at least 16 times daily with lagoon effluent. Ammonia concentrations were measured with a chemiluminescence analyzer by time-sharing it between the barns and ambient air. The treated barn with SOS resulted in 4% less NH 3 emission than the control barn. The mean (± st. dev.) NH 3 concentration and emissions were: 17±8.5 ppm (n=184) and 62±22 g/d-au (n=175), AU=animal unit=5 kg). KEYWORDS. Air quality, air pollution, air pollutants, pig barn, gas INTRODUCTION AND OBJECTIVES Long-term measurements of air emissions from swine housing have shown that ammonia (NH 3 ) emissions may be significant, especially at large sites (Ni et al., 2; Heber et al., 22). The average daily mean NH 3 concentration at a mechanically-ventilated swine barn was 5.6±.41 ppm (mean ± 95% confidence interval) and ranged from 2.8 to 1.6 ppm, and the mean emission rate was 145±1 g/d-au (Ni et al., 2). The authors concluded that barn ventilation significantly impacts NH 3 concentration. Pig mass and indoor temperatures are directly related to NH 3 emission due to greater manure production and a greater amount of manure degradation byproducts. Tao (24) and Heber et al. (24) described the basic results of a study in a swine finishing house using soybean oil sprinkling (two trials), and misting of essential oils with or without water as a carrier. The barns housed 1,1 pigs and were flushed several times daily. Ammonia and several other air pollutants were measured for eleven months. In the test of oil sprinkling, NH 3 emission was 19% less in the treated barn. The NH 3 emission was 16 to 2% less in the barn treated with essential oil spraying. The mean NH 3 concentration and emission were 18 ppm for 132 d and 55 g/d-au for 125 d (AU=animal unit=5 kg). The objective of this paper is to evaluate the concentration and emissions characteristics of NH 3 measured at the two swine finishing barns (Heber et al., 24). METHODS AND PROCEDURES The fan-ventilated swine finishing barns (61. m x 13.2 m x 2.4 m) had two rows of 24 pens with a center alley and four shallow manure gutters under a slatted concrete floor (fig. 1). Each gutter was flushed four times daily with lagoon effluent. Ventilation air entered through ceiling inlets except during warm weather when it entered through curtains on the east end of the barns for tunnel ventilation. In warm weather, the barns were tunnel ventilated with four 1.22-m diameter belted exhaust fans on the west end wall along with one continuous.91-m direct-drive variable speed fan (Heber et al., 22). The north and south barns were denoted B7 and B8, respectively, with B7 the control barn. New pigs arrived at about 25 kg and were harvested at about 123 kg. Odor, NH 3, hydrogen sulfide, non-methane hydrocarbons, and particulate matter were monitored from both barns (Heber et al., 24). The barns were compared to evaluate effects of abatement 436

2 methods applied to B8 for comparison with B7. First, a soybean oil sprinkling (SOS) system automatically applied soybean oil daily in the treated barn from August 28, 22 to February 28, 23. Second, misting of essential oils (MEO) was conducted in the treated barn (March 5 to April 1, 23). The essential oils application was later modified by atomizing a mixture of essential oils and water (MEOW) from June 24 to July 21, 23. Emission measurements in barn 8 were temporarily discontinued between May 2 and June 11, 23, during which a test of another abatement method was conducted to treat the exhaust air of barn 7. Air Sampling Small Propeller Anemometer Relative Humidity/Temperature Static Pressure Port Temperature Sensor Met Tower Lab Barn 7 Barn 8 Fan # Barn 7 Summer Air Inlets Floor plan (61 m x 13.2 m) S Background air sampling Instrument shelter Attic Diffusers Side View Shallow pit with recycle flush Pens 1-5 Figure 1. Barn monitoring plan (Heber et al., 22). Automatic sequential gas sampling from the exhaust of each barn and ambient air at 4 L/min was conducted using filtered and heated Teflon tubes (Heber, et al., 22). The exhaust sampling location was about 1 m away from the continuous winter ventilation fan (fig. 1). Air was sampled for one sampling period at each gas sampling location (GSL). A 1-min sampling period was used for the exhaust locations until Aug. 28 when it was increased to 6 min. The ambient sampling period was increased from 1 to 2 min on Sept. 23. Ammonia was monitored with a chemiluminescence NH 3 analyzer (TEI Model 17C, Thermo Electron Co., Waltham, MA) with a range of 1 ppb to 1 ppm. Its full scale was set between 2-1 ppm depending on the season. Assuming that NO and NO 2 were negligible, the analyzer was operated in the total nitrogen mode. Periodically, the analyzer was calibrated using a programmable diluter and the analyzer s zero and span response was checked twice a week. Fan status was recorded with propeller anemometers (SPA) (R.M. Young Company, Traverse City, MI) at each fan (Heber, 23). A portable fan tester was utilized to measure in-field airflow rates of three fans in B7 and three fans in B8. Electronic transmitters (Model HMW61, Vaisala Inc., Woburn, MA) monitored temperature and humidity at barn fan locations. The HUMICAP TM sensor in these units had ±2% accuracy between and 9% RH and ±3% between 9 and 1% RH. Barn static pressure was measured with a -1 to +1 Pa pressure sensor (Model 267MR, Setra Systems, Inc., Boxborough, MA). Wind was monitored with a cup anemometer (R.M. Young) about 1 m above the ground and solar radiation was monitored with a pyranometer (Li-COR). Three activity sensors (Model SRN-2, Visonic Inc., Bloomfield, CT) monitored pig activity in each barn. Flushing and heating were also monitored (Heber et al, 22). Mean pig mass was estimated from mean weights and animal numbers provided by the producer. The first several readings during each sampling period were invalid because of time required for the analyzer to equilibrate. To obtain continuous gas data to match continuous airflow, the minute-by-minute gas concentration data in long intervals between valid readings were estimated by linear interpolation between intermittent sampling periods. The anchor points for the interpolations were the mean of the last 1 min of the previous sampling period and the first 1 min of valid data from the next sampling period, each located at the midpoint of the 1-min interval. A complete day for a given variable was defined as a day with more than 8% of the data judged to be valid and a full barn was defined as a barn with at least 8% of full capacity. 437

3 Only data collected under the complete days full barn (CDFB) condition was analyzed. Barn Environmental Control RESULTS AND DISCUSSION The basic statistics of several environmental variables are given in table 1 and figs. 2 to 4 show the daily mean temperatures, barn static pressure, airflow rates and relative humidity of exhaust air throughout the test. The ventilation, humidity, and temperature in the barns were quite similar. While the mean ambient temperature and relative humidity was 1 C and 66.1%, respectively, the mean exhaust temperatures in B7 and B8 were 23.2±3.6 C and 22.5±3.6 C, (fig. 2) respectively. The average annual temperature at the site was 1.4 o C based on weather data collected from 1971 to 2 (ggweather.com/normals/mo.htm), thus the test represented typical annual weather. Daily mean barn temperatures ranged from 15 to 3 C and typically exceeded the ambient temperature. Overall mean relative humidities were 54.2±6.1% and 56.3±6.6% in B7 and B8 (fig. 3), respectively. Daily relative humidity exceeded 7% on some occasions in the summer with large pigs and was as low as 4% in the spring with young pigs. The mean static pressures over 252 and 243 d were -16. and Pa in B7 and B8, respectively. Daily means ranged from about -5 Pa in winter to about -4 Pa in summer (fig. 4). Overall mean airflows were 13.1±1.4 (n=231) and 12.5±11.4 m 3 /s (n=232) for B7 and B8, respectively. The observed similarities were expected because the barns were identical in construction, environmental control, and management. Each barn was subjected to the same weather disturbances. The barns were usually loaded simultaneously with similar pig numbers and ages. The cumulative frequency distribution of hourly mean ventilation rates (fig. 5) showed that the summer fans moved a relatively small fraction of the 318,45, m 3 of fresh air that flowed through the barn during the 6661 h represented by the graph. Specifically, the amounts of ventilation air provided by less than 25, 5, 75 and 9% of the maximum barn capacity of 38.3 m 3 /s were 54.6, 79.1, 93.3 and 98.8% of time, respectively. Half the time, the ventilation rate was 8.6 m 3 /s (22.5% of total capacity) or less. The barn airflow rate was less than 4.3 m 3 /s (11.1% of total capacity) for 25% of the time, and less than 18.8 m 3 /s (49.1% of total capacity) for 75% of the time. These relationships indicate that air treatment systems (e.g. biofilters) should be installed first on the cold weather fans for the greatest cost/benefit ratio. Also, diminishing benefits occur as they are installed on a greater number of fans, which operate less and less Temperature, o C Ambient T Barn 7 Barn 8-3 8/22 9/26 1/31 12/5 1/9 2/13 3/2 4/24 5/29 7/3 8/7 Date, mm/dd Figure 2. Daily mean barn and ambient temperatures. 438

4 Exhaust Relative Humidity, % Barn 7 Barn 8 8/22 9/26 1/31 12/5 1/9 2/13 3/2 4/24 5/29 7/3 8/7 Date, mm/dd Figure 3. Daily mean exhaust relative humidity in barns 7 and Static pressure, Pa dp B7 dp B8 Airflow B7 Airflow B Ventilation Rate, m 3 /s /22 9/26 1/31 12/5 1/9 2/13 3/2 4/24 5/29 7/3 8/7 Date, mm/dd Figure 4. Daily mean barn static pressures and airflow rates. 5 4 Airflow rate, m 3 /s 3 4 Temperature Airflow Temperature, o C Fraction of Time Figure 5. Frequency distribution of hourly mean airflow rates and their corresponding temperatures in B7. Ammonia Concentrations and Emissions The daily mean NH 3 concentrations ranged from 1.2 to 37 ppm (table 1) and averaged 17 and 14 ppm in B7 (n=175) and B8 (n=129), respectively. The overall mean concentration was lower in B8 because it was the treated barn in several tests (Heber et al., 24). The NH 3 level was 439

5 influenced by ventilation as the highest concentrations were observed in January and the lowest were observed in July (fig. 6). Ventilation was controlled to maintain inside temperature, and higher ventilation in warm weather diluted gas concentrations. The cumulative frequency distribution (fig. 7) indicates that NH 3 concentration in B7 was less than 9, 17, 2, 23, 25, and 29 ppm 25%, 5%, 7%, 75%, 83% and 9% of the time. The associated airflow rates show a very strong correlation with concentration (r = -.78). Since airflow is coupled with temperature, the daily mean concentration also correlated well with daily mean outdoor temperature (r = -.82) and indoor temperature (r = -.71). The daily mean concentration was directly proportional to daily mean pig activity as indicated by the correlation coefficient of.57 (table 2). Seasonal trends in activity occurred, with higher and lower values in cold and warm weather, respectively. Table 1. Average daily means (St. Dev.) of NH 3 and other variables. Parameter Control Barn (7) Treated Barn (8) Barn inventory of pigs Pig mass, kg Stocking density, kg/m Animal activity, mv (output from activity sensors) Ambient temperature, o C 9.98(11.4) Ambient relative humidity, % 66.1(11.) Wind speed, m/s 3.68(1.71) Exhaust temperature, o C 23.2(3.64) 22.5(3.61) Exhaust relative humidity, % 54.2(6.1) 56.3(6.57) Ventilation rate, m 3 /s 13.1(1.4) 12.5(11.4) Static pressure, Pa -16.(8.58) -19.5(8.85) Test duration, d 29 8% full % valid data Complete data full barn (CDFB) Concentrations, ppm n=184 n=129 Mean 16.9(8.46) 14.2(8.3) Maximum Minimum Median Emission rates n=175 n=125 Mean, kg/d 8.9(2.5) 6.5(2.61) Maximum, kg/d Minimum, kg/d Median, kg/d Mean, g/d AU 62.(21.6) 41.7(15.7) Maximum, g/d AU Minimum, g/d AU Median, g/d AU Mean, g/d pig 7.27(2.39) 6.2(2.52) Maximum, g/d pig Minimum, g/d pig Median, g/d pig

6 Emission Rate, g/d-au Barn 7 Barn 8 Emission rate Barn 7 Barn 8 Concentration B7 Pig Mass B8 Pig Mass 8/22 9/26 1/31 12/5 1/9 2/13 3/2 4/24 5/29 7/3 8/7 Date, mm/dd Figure 6. Daily mean ammonia concentration and emission rate Concentration, ppm Total Live Mass, AU The overall mean emission rates were 8.1 and 6.5 kg/d in B7 (n=175) and B8 (n=125), respectively, but only B7 represents baseline emissions since B8 was abated in various tests. The average daily mean normalized NH 3 emission rates were 62 and 42 g/d-au in B7 and B8, respectively (table 1). The B7 emission rate was correlated to outdoor temperature and ventilation rate with correlation coefficients of.23 and.26 (table 2). As expected, it was also directly proportional to total live mass (r=.45). Concentration, ppm; Airflow rate, m 3 /s Airflow % 1% 2% 3% 4% 5% 6% 7% 8% 9% 1% Percent Time Less Than Concentration Figure 7. Frequency distribution of NH3 concentration and its corresponding airflow rate. Table 2. Correlations between barn 7 daily NH 3 concentrations and emissions (mg/s) and other variables. Variable Ammonia Concentration Emission rate Indoor temperature -.71 *.3 * Outdoor temperature -.82 *.23 * Pig activity.57 * -.27 * Ventilation rate -.78 *.26 * Total live mass -.24 *.45 * *p<.5 The overall mean activity signal in B7 was 26 mv. The absolute value was arbitrary but the variation of the signal was the essential indicator of pig activity. Different diurnal patterns were observed in this study. The hourly mean NH 3 emission rate displayed a distinct diurnal pattern 441

7 that corresponded to pig activity and the pattern was apparently influenced by the weather (fig. 8). The composite average diurnal patterns of emission and activity were calculated for each of the three groups of pigs. The average temperatures for groups 1-3 were 12., 2.1 and 21.5 C, respectively. Group 2 with the coldest mean outside temperature of 2.1 C exhibited single dominant broad peaks during the day (fig. 8). Groups 1 and 3 exhibited two peaks, a major peak in the morning and a minor peak in late afternoon. An analysis of monthly periods revealed a strong influence of outdoor temperature on the time of day at which the major peak occurred. The time of peak emission rate shifted from 14: at an outdoor temperature of -4 C to 6: at an outdoor temperature of 25 C. The number of peaks changed from one to two as outdoor temperature increased to 5 C (fig. 9). Building emission models need to consider these effects on NH 3 emission rate Group 1 Group 2 Group 3 Group 1 Group 2 Group 3 NH3 Emissions, mg/s-au Animal Activity, v Activity Emission rate Time of day (h) Figure 8. Hourly mean animal activity and NH 3 emission rates for (a) group 1 with average outdoor temperature T o = 12 o C; (b) group 2 with T o = 2.1 o C and (c) group 3 with T o = 21.5 o C Time of Day, h Time of daily maximum emission Number of emission peaks 2 1 Number of peaks Monthly mean outdoor temperature, o C Figure 9. Relationship between monthly mean outdoor temperature and (1) time of day at which daily maximum mean emission occurred, and (2) number of daily emission peaks. CONCLUSIONS 1. The overall mean NH 3 concentration was 17 and 14 ppm in B7 (n=184) and B8 (n=129), respectively. 2. The overall mean NH 3 emission was 62 and 42 g/d-au in B7 (n=175) and B8 (n=125), respectively. 3. The hourly NH 3 emission was correlated with indoor and outdoor temperature, 442

8 ventilation rate, and total live mass. 4. Pig activity and NH 3 emission rate displayed similar diurnal patterns that were influenced by season. ACKNOWLEDGEMENTS Premium Standard Farms, the Multi-State Consortium on Animal Waste at the University of Missouri, the Purdue Research Programs, and the University of Missouri Extension Service provided financial support. REFERENCES 1. Heber, A.J. 23. Air emission measurements at livestock houses: a hide-and-seek challenge to find the numbers. Resource 1(4): Heber, A.J., J.-Q. Ni, T.-T. Lim, P.C. Tao, A.M. Millmier, L.D. Jacobson, R.E. Nicolai, J. A. Koziel, S.J. Hoff, Y. Zhang, and D.B. Beasley. 22. Quality assured measurements of animal building emissions: Part 1. Gas concentrations. Symposium on Air Quality Measurement Methods and Tech., San Francisco, CA: Nov , Air & Waste Management Assoc.: Pittsburgh, PA. 3. Heber, A.J., T.-T. Lim, P.C. Tao, J.-Q. Ni, and A.M. Schmidt. 24. Control of air emissions from swine finishing buildings flushed with recycled lagoon effluent. Paper #44156, ASAE, St. Joseph, MI, Ni, J.Q., A.J. Heber, T.T. Lim, C. Diehl, R. Duggirala, B. Haymore, and A. Sutton. 2. NH 3 emission from a large mechanically-ventilated swine building during warm weather. J. Env. Qual. 29: Tao, P.C. 24. Abatement of Air Emissions from Swine Finishing Barns. M.S. Thesis. Purdue University, West Lafayette, IN