AIR POLLUTANT EMISSIONS FROM TWO HIGH-RISE
LAYER BARNS IN INDIANA
Paper # 1368
Albert J. Heber*, Ji-Qin Ni*, Teng T. Lim*, Rudy Chervil*, Pei C. Tao*, L.D. Jacobson, S.J.
Hoff, Y. Zhang, J. Koziel and D.S. Beasley.
*Agricultural and Biological Engineering, Purdue University, 225 S University Street, West
Lafayette, IN 47907-2093
ABSTRACT
Baseline gas, odor and PM emissions were collected from two, 250,000-hen layer barns over a
period of 15 months using state-of-the-art continuous emission monitoring equipment. The tests
began on December 8, 2002 and were completed on March 8, 2004. The data collected included
concentrations of ammonia (NH3), hydrogen sulfide (H2S), carbon dioxide (CO2), and particulate
matter (PM10), and odor both at the exhaust fans and in the bird occupation zones. Other
variables measured included inside and outside temperature, relative humidity, and building
static pressure, wind speed and direction, bird activity, fan operational status and barn ventilation
rate. Continuous data was acquired every second by a computerized data acquisition system and
60-second averages were recorded every minute. Discrete odor samples were evaluated offline.
The data are very important to the livestock industry, government regulators, and university
scientists and engineers. It will be used by the U.S. EPA to set policy related to air pollution
standards (Clean Air Act, CERCLA, EPCRA). The egg production industry will use the data to
help them comply with new animal welfare standards relating to ammonia concentrations and to
compare alternative barn design and management strategies to reduce emissions. Mean emission
rates were 287.7±27.2 g (mean±standard deviation), 0.62±0.11 g, 24.9±0.9 kg, and 3202±312 g
per day per AU (animal unit=500 live mass) for NH3, H2S, CO2 and PM10, respectively. Average
odor emission from the two barns was 6.1 OUE per second per m2 barn area.
INTRODUCTION
Large animal confinement buildings are becoming more common because they effectively
reduce unit costs of production. Air pollutants produced in these barns represent a risk to the
health and well-being of animals and of workers, and pollution to the environment 1. Aerial
pollutants of particular interest in livestock barns are ammonia (NH3), hydrogen sulfide (H2S),
and particulate matter (PM10 and TSP) 2-5. Odor emitted from barns contribute to nuisance
experienced in areas surrounding livestock production 6,7. Carbon dioxide (CO2) emissions are
thought to be an important greenhouse gas but vegetation provides a substantial sink and the
primary reason for measurement of CO2 is for the assessment of building ventilation 8. Von
Wachenfelt et al (2001) 9 found a large diurnal variation in CO2 production, closely correlated to
measured animal activity; the average CO2 production during the 12-h dark period was only 66%
of the production during the day.
While several air emission studies have been conducted previously, baseline data from
comprehensive, long term, and continuous emission measurements at large U.S. layer barns are
still needed. Federal and state regulators are more strictly regulating poultry facilities recently.
1
Therefore, the objective of this paper is to report NH3,H2S, CO2, odor and PM emissions from
two modern high-rise caged-layer barns 10.
MATERIALS AND METHODS
This experiment was conducted in two caged-hen layer barns in north-central Indiana that were
located on a farm about 64 km (40 mi.) from the West Lafayette campus of Purdue University.
The two barns were constructed in 2002 and measurements were taken with the first group of
hens in each barn.
Experimental Barns
The barns (Barns 13 and 14) were oriented E-W and spaced 75 ft (22.9-m) apart. The roofs of the
barns had a 3:12 slope. Each barn was 610 ft x 99-ft. (186.0-m x 30.2-m) and housed 250,000
hens in ten 580-ft (176.8-m) rows of crates (5 tiers high) in the 10.8-ft (3.29-m) high upper floor
(Figure 1). Manure was scraped off boards under the cages into the 10.33-ft (3.15 m) high
manure pit where it was stored for 24–30 months. Manure drying on the pit was enhanced with
36 in. (918 mm) dia. auxiliary circulation fans (Model #40404-36, Choretime-Brock, Inc.,
Milford, IN).
2
Figure 1. Front view (top) and floor plan (bottom) of the barns and the measurement set up
showing schematically the measurement locations and real-time values during a summer day.
Blue dot: air sampling locations and calibration gas inlet; Green dot: locations where air was
being sampled; Green oval: ventilation exhaust fans.
Ventilation air entered the second floor from the attic through temperature-adjusted baffled
ceiling air inlets over the cages. Incoming air passed through evaporative cooling cells (8.92 ft or
2.72 m) in the roof of the attic, which were operated only when all fans were operating and when
temperature exceeded a set-point. There were 37 fans (#1-#37) along the west sidewall and 38
fans (#38-#75) on the east sidewall. All fans were 48-in. (122 mm) dia. belted exhaust fans
(Aerotech Model AT481Z3CP-24 with 1.0-Hp Motor (PN B-176835-04, General Electric) fans.
The fans were 12 ft (3.7 m) apart in groups of three or four fans and most of the groups were 24
ft (7.3 m) apart. Each barn had 15 temperature sensors and was ventilated in 9 stages (Table 1).
The first and second stages consisted of 5 and 7 fans, respectively. The cage lights were shut off
automatically between 20:00 and 04:00 h each night.
Table 1. Fan numbers and ventilation stages for Barn 14*.
Stage
Number of fans
1
2
3
4
5
6
7
8
5 (continuous)
5+5=10
10+8=18
18+8=26
26+8=34
34+8=42
42+14=56
56+19=75
9
75-19=56
ID of fans for each stage
1, 20, 37, 47, 67
10, 29, 39, 57, 75
5, 15, 24, 33, 43, 52, 62, 71
6, 16, 25, 34, 44, 53, 63, 72
4, 14, 23, 32, 42, 51, 61, 70
7, 17, 26, 35, 45, 54, 64, 73
3, 9, 12, 18, 22, 28, 31, 38, 40, 49, 55, 59, 65, 69
2, 8, 11, 13, 19, 21, 27, 30, 36, 41, 46, 48, 50, 56, 58, 60, 66,
68, 74
Evaporative pads on, stage 8 fans off
* Fans for stages 1 and 2 were swapped in Barn 13 to bring a stage 1 fan of each building close
to the instrument shelter.
Equipment and Measurement
Instrument Shelter
An air-conditioned trailer of 24 ft x 8 ft x 7 ft (7.32 m x 2.43 m x 2.13 m) located between the
two barns was used to shelter instruments and to provide lab and office space for researchers to
conduct on-site experiments (Figure 1). The instrument shelter was connected to the barns via
two 4-inch (10 cm) ID PVC pipe raceways, which housed sampling tubing and signal cables.
The raceways were heated to prevent condensation in cold weather.
Gas Concentrations
Air was drawn sequentially from different locations in the barns by a gas sampling system and
provided to the gas analyzers in the instrument shelter (Figure 2). Six sampling locations in each
3
barn were selected. The sampling location at the cage in each barn was composed of three
sampling spots, which were connected together to a manifold, forming a sampling location group
along the length of the barn. All other samplings were from single location (Figure 1).
Bypass pumping circuit
P: pump
F: filter
M: manifold
S: solenoid
Teflon tubing (in mm):
9.5 OD 6.4 ID
6.4 OD 3.2 ID
3.2 OD 1.6 ID
Vinyl tubing (in mm):
6.4 OD 3.2 ID
22.2 OD 15.9 ID
Fittings:
Teflon
Nylon or other
Flow restrictor
Exhausts
M1
P1
Analyzers
NH3
P3
Sampling probes, 10-115 m long
S1
H2S
13F29
Bag fill
port
14F67
14Cage
M3
CO2 (2K)
14Attic
F
14F47
14F20
CO2 (10K)
13F59
f
M2
13F10
14F1
Mass
flow meter
P2
13Cage
13Attic
Exhaust
13F75
F
S12
Exhaust
Rotameter
(0-350 mL/min)
Balance air
control valve
Mass
flow meter
Sampling circuit
Solenoids are all at un-energized positions
P
Pressure gage
(optional)
S13
Pressure
sensor
Disconnect for
leakage test
f
p
Analyzer calibration
circuit
Cal gases
P4
Jar
Leak test
circuit
S14
Figure 2. Flow diagram of air sampling, gas measurement, instrument calibration and system
maintenance.
Sampling in the attics (one location in each barn at about 10 cm above the baffled ceiling
opening) and selected barn stage 1 fans (four fans in each barn) were to determine inlet and
exhaust gas concentrations, respectively. The four exhaust sampling locations, about 0.5 m
directly in front of the fan at the same height as the fan hub, in each barn included two fans on
the west sidewall and two fans on the east sidewall. Sampling in the cages, located in an emptied
cage that is about 0.75 m above the 15-cm wide manure slot through which ventilation air enters
the pit from the cage area, was to evaluate the bird’s exposure to pollutant gases. Sequence and
duration of sampling (10 min each location) were controlled by a computer in the instrument
shelter.
Ammonia concentrations were measured with a 0-200 ppm chemiluminescence NH3 analyzer
(Model 17C, TEI, Inc., Waltham, MA) after conversion to NO. The analyzer sampled at a flow
rate of 0.6 L min-1 with an external vacuum pump (Model PU426, KNF Neuberger, Trenton, NJ).
Although the nominal range of the NH3 analyzer was 100 ppm, it was increased to 200 ppm by
reducing instrument sensitivity by 50%.
Hydrogen sulfide (H2S) was first converted catalytically at 400°C to sulfur dioxide (SO2) with a
H2S converter (TEI Model 340). The converted SO2 was measured with a pulsed fluorescence
SO2 Analyzer (TEI Model 45) according to USEPA Method EQSA-0486-060. A photomultiplier
tube detected ultraviolet light emission from decaying SO2 molecules. The SO2 analyzers had a
4
range of 0.05 to 10 ppm, a response time of 60 s (10-s averaging time), and a sample flow rate of
1.0 Lpm. The guaranteed precision was 1% of reading or 1 ppb (whichever is greater).
Carbon dioxide was measured with two photoacoustic infrared gas monitors (Model 3600, Mine
Safety Appliances Company, Pittsburgh, PA), with 0-2000 and 0-10,000 ppm measurement
ranges, respectively. The monitors utilized dual frequency infrared absorption and were
corrected for water vapor. Their precision was 2% or ±100 ppm, and sample flow rate was 1.0
Lpm. The monitors had internal pumps and internal filters.
All the gas analyzers/monitors were calibrated with zero and certified calibration gases at least
once per week.
Particulate Matter
Particulate matter (PM) was measured with a TEOM ambient PM10 monitors (Model 1400a,
Rupprecht & Patashnick, Albany, NY) immediately upstream of Fan #20 in Barn 13 and Fan #59
in Barn 14. The TEOM is a continuous monitoring device and is designated as an equivalent
method by the U.S. EPA (EPA Designation No. EQPM-1090-079) for PM10. The TEOM
operates on changes in the resonant frequency of an oscillating element as a function of increases
in particle mass collected on an attached filter. Changes in the recorded resonant frequency of the
element provide continuous and time-averaged measurement of mass accumulation. The device
operates at a flow rate of 16.7 L/min, so that it can be outfitted with commercially available preseparator sampling inlets for measuring TSP and PM2.5.
Odor Concentration
Odor samples were collected using 0.05 mm thick, 10-L, Tedlar bags at the “bag fill port” of the
gas sampling system (Figure 2). The bags were flushed with either compressed air or nitrogen
gas at least three times prior to the sampling. New bags were used for each sample collection as
recommended by the European draft olfactometry standard CEN TC26411. To reduce adsorption
losses, 2-3 L of sample air was introduced into each bag and removed before filling the bag with
sample air. The samples were evaluated on the same day during a 3.5 h (maximum) olfactometry
session.
Odor dilutions-to-threshold were measured on the same day with a dynamic dilution forcedchoice olfactometer (AC'SCENT International Olfactometer, St. Croix Sensory, Stillwater,
Minn.) according to U.S. olfactometry standards12. The odor panel consisted of eight human
subjects that were screened to determine their odor sensing ability13. The olfactometer delivered
precise mixtures of sample and dilution air to a Teflon-coated presentation mask at a total flow
rate of 20 L/min. The dilution ratio of a mixture was the ratio of total diluted sample flow
volume to the odor sample flow volume. The panel average of individual dilutions-to-thresholds
was given the concentration units of OU/m3 per the CEN TC264 standard.
Fan Operation, Ventilation Airflow and Static Pressures
The operating status (on/off) of each fan stage was monitored via auxiliary contacts of fan motor
control relays. Fan airflow capacities were measured in the field with a portable fan tester 14
consisting of multiple traversing impellers. The fan tester was calibrated at the University of
Illinois Bioenvironmental Systems and Simulations (BESS) Laboratory with an accuracy of
±2%. Additionally, eight impeller anemometers (Model EXAVENT FMS 50, Fancom,
5
Panningen, The Netherlands) were installed inside the top of fan cones of the eight monitored
ventilation fans.
Static pressures between the center of the manure pit and both the east and west sides of the
barns were measured with differential pressure sensors (Model 267, Setra, Boxborough, MA).
The sensors’ measurement range were ±100 Pa with an accuracy of ±0.25%.
Relative Humidity, Temperature, and Wind
One capacitance-type relative humidity (RH) and temperature probe (Model HMW61, Vaisala,
Inc., Woburn, MA) was set up at the same sampling locations as the TEOM in each barn.
Another RH/T probe (Model Humitter 50Y, Vaisala, Inc.) was located in one emptied cage in the
middle of each barn. A solar radiation shielded RH/T probe (Model HMD60YO, Vaisala, Inc.)
and a cup anemometer and wind vane were attached to the top of one feed bin near the
instrument shelter.
Thermocouples (Type T) were installed to measure temperatures at the baffle air inlet and at
exhaust fan locations, where RH/T probes were not set up. Thermocouples were also installed in
the heated raceways between the barns and the instrument shelter, inside the instrument shelter,
and the shelter compartment where TEOM and ammonia analyzer sampling pumps were housed.
Data Acquisition and Control
A special data acquisition (DAQ) and control program was developed for this study using
LabVIEW for Windows (National Instruments Co., Austin, TX). The program ran in a PC and
communicated with DAQ hardware, which included a bank of FieldPoint modules (National
Instruments Co.), and a PCI 6601 DIO card (National Instruments Co.). A PCIM-DAS1602/16
DAQ card and an expansion board (EXP 32, Measurement Computing Corporation, Middleboro,
MA) was also installed to add additional 32 analog input channels.
Data acquired by the DAQ system were sampled at a frequency of 1 Hz, then averaged every 15s
and 60s, and saved into two data files, respectively. Saved in the data files were also time stamps
and air sampling locations.
Data Processing
Custom data processing software CAPECAB was used to process the 1-min data set 15,16.
Gas concentrations of each sampling location or location group were divided into invalid data, at
the beginning of the 10-min sampling cycle, and valid data, at the end of the cycle. The duration
of invalid data depends on the time required for equilibrium of the measurement system,
especially the gas analyzer. The valid gas concentration data was extracted for emission
calculations (Table 2).
There were only 3 to 7 valid readings per emission stream during a 120-min sampling cycle. Gas
concentrations in the intervals between valid readings were estimated by linearly interpolating
between valid readings. The maximum interval of missing data that was interpolated was 300
min.
PM and odor concentrations were converted to concentrations at STP (20°C, 1 atm) for
calculating emissions.
6
Table 2. Extraction of gas concentration data.
Gas
Ammonia
Hydrogen sulfide
Carbon dioxide
Invalid time (min)
Valid time (min)
7
5
3
3
5
7
The calculation of emission with a single ventilation exhaust sampling location was:
E   QoCo  QC
i i    Q ' oC ' o  Q 'i C 'i 
(1)
Where,
E,
Ci
Co
Ci’
Co ’
Qo
Qi
Qi’
Qo’
Barn emission rate, mg/s or µg/s
Mass concentration at the barn air inlet, mg/m3 or µg/m3
Mass concentration at the barn air exhaust, mg/m3 or µg/m3
Standardized mass concentration at the barn air inlet (based on STP), mg/sm3 or µg/sm3
Standardized mass concentration at the barn exhaust (based on STP), mg/sm3 or µg/sm3
Barn outlet moist airflow rate at To, m3/s
Barn inlet moist airflow rate at Ti, m3/s
Moist standard ventilation rate at the barn inlet (based on STP), sm3/s
Moist standard ventilation rate at barn exhaust (based on STP), sm3/s
The barn emission rate with multiple sampling locations corresponding to multiple ventilation
exhausts was:
n
E   Qo ,k  Co ,k  Ci  
(2)
k 1
Where,
E
Co,k
Ci
Qo,k
Gas emission rate from the barn, mg/s
Mass concentration at a specific ventilation exhaust k, mg/m3 or µg/m3
Mass concentration in the incoming ventilation air, mg/m3 or µg/m3
Ventilation rate corresponding to concentration measurement location k, m3/s
To avoid errors introduced into the calculated average values due to partial data days (e.g. only 3
night time hours of valid data) that resulted in biased time weights, only complete-data days that
include over 70% valid data was used for calculating average daily means (ADM).
RESULTS AND DISCUSSION
Table 3 presents partial results of gas and PM10 emissions, from August 13 to November 23,
2003 (a total of 105 days), of the 15-month measurement campaign. The complete data days of
the gases and PM ranged from 57 to 97 days, about 54% to 92% of the measurement period.
Ammonia emission rate from Barns 13 and 14 were 278.8±33.8 and 298.3±43.8 g per day per
AU (animal unit=500 kg live mass), respectively, only less than 7% difference. Lim et al.
7
(2004) 5 studied NH3 emission from a 250,000 layer barn from September 2001 to May 2002.
The average NH3 emission rate from 125 complete data days of data was 200 g/d-AU. It was
only about 70% of the average emission rate of Barns 13 and 14.
Hydrogen sulfide emission rates were low from both barns, 0.49±0.09 g/d-AU from B13 and
0.75±0.19 g/d-AU from B14. Hydrogen sulfide is not a major concern among air pollutants
emitted from poultry barns. The mean H2S emission rate from a 250,000-hen layer barn reported
by Lim et al. (2003) 17 was 5.6 µg/s-AU or 0.48 g/d-AU, which was similar to the emission rate
from Barn 13. Barn 14 emitted 53% more H2S than Barn 13.
The range of CO2 from the two barns using two carbon dioxide monitors was from 24.5±1.3 to
25.0±1.4 kg/d-AU. The average emission rate from the two barns with the two monitors was
24.9±0.7 kg/d-AU.
Table 3. Emission rates of ammonia, hydrogen sulfide, carbon dioxide and PM10 from the two
barns.
Pollutant
Barn
Complete data Days
Emission rate per day per AU*
NH3
B13
B14
Mean
B13
B14
Mean
B13
B14
Mean
B13
B14
Mean
B13
B14
Mean
69
57
278.8±33.8 g
298.3±43.8 g
287.7±27.2 g
0.49±0.09 g
0.75±0.19 g
0.62±0.11 g
25.0±1.4 kg
24.9±1.5 kg
25.0±1.0kg
24.5±1.3 kg
25.1±1.3 kg
24.8±0.9kg
2878±334 g
3489±501 g
3202±312 g
H2S
CO2 (2k)
CO2 (10k)
PM10
72
68
77
67
75
73
86
97
* Mean±95% confidence interval.
PM10 emission was higher from Barn 14 (3489±501 g/d-AU) than Barn 13 (2878±334 g/d-AU).
Odor emissions from five days of sampling, three samples each day in each barn, are listed in
Table 4. Barn odor emission rates ranged from 3,898 to 109,683 OU/s (OU=Odor Unit), or from
4,898 to 100,138 OUE/s (OUE=European Odor Unit). Averaged odor emissions per unit area
were 6.5 and 7.9 OU/s-m2, or 5.6 and 6.7 OUE/s-m2, for Barn 13 and Barn 14, respectively.
These emission values were lower than the 7.53 OUE /s-m2 reported by Lim et al. (2003)17.
Table 4. Odor emission rates from the two barns.
Date
Sample #
B13 OU/s
B13 OUE/s
B14 OU/s
B14 OUE/s
8
8/18/2003
9/2/2003
9/15/2003
9/29/2003
10/13/2003
10/31/2003
11/14/2003
Mean
Min
Max
Emission per m2
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
70538
48055
71205
57818
66050
75993
24162
20174
19951
26501
35571
13562
3898
10086
10217
74870
53060
53064
11447
10381
9397
36476
3898
75993
6.5
62248
42407
62836
36744
41977
48296
19953
16659
16476
19902
26713
10184
4898
12674
12839
84135
59626
59630
8499
7707
6977
31494
4898
84135
5.6
41312
47936
47924
97921
98846
109683
36861
23065
27303
36934
40498
18769
4512
4590
63611
63372
89111
8840
12102
12175
44268
4512
109683
7.9
36456
42302
42291
62231
62819
69706
35897
23222
27134
24446
26865
12127
5670
5768
71483
71215
100138
6563
8985
9039
37218
5670
100138
6.7
CONCLUSION
The following air pollutant emission data were obtained from the two barns during 105 days.
1. Ammonia emission from Barns 13 and 14 were 278.8±33.8 and 298.3±43.8 g/d-AU,
respectively.
2. H2S emission rates were 0.49±0.09 and 0.75±0.19 g/d-AU from B13 and B14.
3. The range of CO2 from the two barns was 24.5±1.3 to 25.0±1.4 kg/d-AU. The average
emission rate from both barns was 24.9±0.7 kg/d-AU.
4. PM10 emission was higher from Barn 14 (3489±501 g/d-AU) than Barn 13 (2878±334
μg/d-AU).
5. Mean odor emissions were 6.5 and 7.9 OU/s-m2, or 5.6 and 6.7 OUE/s-m2, for Barns 13
and 14, respectively.
9
ACKNOWLEDGMENTS
The authors would like to thank the United States Department of Agriculture for funding this
research project under the USDA-IFAFS research and demonstration program. This work is
dedicated to the memory of the late Dr. Bob Bottcher, our colleague and friend.
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