Erin L. Cortus

The National Air Emissions Monitoring Study: Overview of Barn Sources

The National Air Emissions Monitoring Study (NAEMS) is required by a U.S. EPA air consent agreement, in which livestock producers agreed to collect air emission data in exchange for more time to report their emissions and apply for any necessary permits. Field measurement of livestock air emissions is a major part of the study. Compared with most previous field studies of barn air quality, the NAEMS was designed to have 1) several pollutants measured simultaneously including particulate matter (PM), ammonia (NH3), hydrogen sulfide (H2S), and non-methane volatile organic compounds (NMVOC), 2) a long duration of two years, 3) a large number of measured barns (38) using the same protocol, 4) careful selection of farms to enhance their representativeness, and 5) a high level of quality assurance and quality control as required by the U.S. EPA, which is supervising the study. The NAEMS is collecting continuous air emission data from 38 barns at five dairies, five pork production sites, three egg layer operations, one layer manure shed, and one broiler facility for a period of 2 years starting in 2007. At each barn monitoring site, an on-farm instrumentation shelter houses equipment for measuring pollutant concentrations at representative barn air inlets and outlets, barn airflows, operational processes, and environmental variables. A multipoint gas sampling system delivers selected air streams to gas analyzers. Mass PM concentrations are measured at one representative exhaust location per barn using real-time monitors. Motion sensors monitor activity of animals, workers and vehicles. Building ventilation rate is assessed by monitoring fan operation and building static pressure in mechanically ventilated barns, and air velocities through ventilation openings in naturally-ventilated buildings. Data is logged every 15 and 60 s and retrieved with network-connected PCs, formatted, validated, processed, and delivered to the U.S. Environmental Protection Agency (EPA).

Air Emissions from Broiler Houses in California

The emission rates (ER) of ammonia, carbon dioxide, hydrogen sulfide, and particulate matter (PM) (PM2.5, PM10, and total suspended particulate, TSP) were monitored at two broiler houses in California from September 2007 to October 2009. Each of the two identical buildings housed an average of 21,000 broilers raised in 46 d growth cycles with a space allowance of 1430 cm2 bird-1 and an average market weight of 2.65 kg. The litter in each house was partially replaced after the first and second flocks and completely replaced after the third flock in a three-flock litter management cycle. The environment of each house was controlled by 11 single-speed ventilation fans, two evaporative cooling cells, and 17 heaters. The average daily mean (±SD) ERs of ammonia, carbon dioxide, and hydrogen sulfide were 0.503 ±0.436, 78.3 ±47.5, and 0.00289 ±0.00251 g d-1 bird-1, respectively. The average daily mean ER of PM10 was 45.0 ±39.0 mg d-1 bird-1. The influences of environmental conditions and other factors on ERs were assessed. The ERs were influenced by broiler weight or age, ambient temperature, and litter status, with the exception of PM, which was not influenced by litter status.

Effectiveness of a Manure Scraper System for Reducing Concentrations of Hydrogen Sulfide and Ammonia in a Swine Grower-Finisher Room

The effectiveness of a manure scraper system for reducing the risk of barn worker and animal exposure to hydrogen sulfide (H2S) was evaluated by comparing gas levels in two swine production rooms, one with a manure scraper system installed (scraper) and the other with a conventional manure pit-plug system (control). Measurements were done over four production cycles; during each 12-week cycle, gas concentrations were measured 4 to 5 times during weeks that conventional manure removal activities were performed in the control room, while the scraper system was operated daily in the scraper room. Daily removal of manure from the scraper room resulted in measured maximum H2S concentrations that were significantly lower (by 90%) compared to the control room. The type of manure removal system had no significant effect on ammonia (NH3) concentration and emission; during each trial, NH3 emission increased in both rooms over the 4 to 5 monitored weeks. The scraper system was also operated in two different modes. These tests revealed that NH3 production was reduced when all the manure was removed from the room compared to leaving the liquid portion on the pit floor surface, although the differences were not significant (p > 0.10). The estimated cost of including the scraper system in the construction and operation of a new barn is CDN

Ventilation rates in large commercial layer hen houses with two-year continuous monitoring.

1.89 per pig sold, which is 35% less (on a per pig basis) than the cost of retrofitting an existing facility. The manure removal system tested was effective in reducing exposure of workers and animals to H2S, without significant adverse impact on NH3 production. However, given the highly variable nature of H2S production and dispersion within a room, care should always be taken when handling manure inside swine barns.

Using CAPECAB to Process Emission Data in the National Air Emissions Monitoring Study

1. Ventilation controls the indoor environment and is critical for poultry production and welfare. Ventilation is also crucial for assessing aerial pollutant emissions from the poultry industry. Published ventilation data for commercial layer houses have been limited, and are mostly based on short-term studies, mainly because monitoring airflow from large numbers of fans is technically challenging. 2. A two-year continuous ventilation monitoring trial was conducted at two commercial manure belt houses (A and B), each with 250 000 layers and 88 130-cm exhaust fans. All the fans were individually monitored with fan rotational speed sensors or vibration sensors. Differential static pressures across the house walls were also measured. Three fan performance assessment methods were applied periodically to determine fan degradations. Fan models were developed to calculate house ventilations. 3. A total of 693 and 678 complete data days, each containing >16 h of valid ventilation data, were obtained in houses A and B, respectively. The two-year mean ventilation rates of houses A and B were 2·08 and 2·10 m3 h−1 hen−1, corresponding to static pressures of −36·5 and −48·9 Pa, respectively. For monthly mean ventilation, the maximum rates were 4·87 and 5·01 m3 h−1 hen−1 in July 2008, and the minimum were 0·59 and 0·81 m3 h−1 hen−1 in February 2008, for houses A and B, respectively. 4. The two-year mean ventilation rates were similar to those from a survey in Germany and a 6-month study in Indiana, USA, but were much lower than the 8·4 and 6·2 m3 h−1 hen−1 from a study in Italy. The minimum monthly mean ventilation rates were similar to the data obtained in winter in Canada, but were lower than the minimum ventilation suggested in the literature. The lower static pressure in house B required more ventilation energy input. The two houses, although identical, demonstrated differences in indoor environment controls that represented potential to increase ventilation energy efficiency, and reduce carbon footprints and operational costs.

Dynamic Simulation of Ammonia Concentration and Emission within Swine Barns: Part I. Model Development

CAPECAB (Calculation of Air Pollutant Emissions from Confined Animal Buildings) is customized software used in the National Air Emissions Monitoring Study (NAEMS) as an efficient data processing tool that reduces data storage space, provides a user-friendly interface to review and process data, and most importantly, aids in producing quality-assured emission data from livestock and poultry facilities. CAPECAB was originally developed in 2003 and has since been used in data processing for numerous livestock-emission projects. For the NAEMS, CAPECAB underwent significant improvements to allow for multiple methods of data review and data validation/invalidation, as well as faster processing speed overall. CAPECAB stores all data for a site in a binary database, which greatly reduces the storage space compared with traditional methods (i.e. spreadsheet files) and enables the user to view one or multiple variables for time ranges spanning from minutes to over one year without manually opening several files. Other features of CAPECAB, such as the user interface, built-in functions (including statistical and histogram features), data validation/invalidation system, and table generation are also discussed in terms of data storage space, quality control, and ease of use.

Ventilation Monitoring of Broiler Houses in California

A process-based model is described that simulates the dynamic ammonia concentration in the room and in the slurry channel headspace of grower-finisher swine barns, as well as the ammonia emitted to the surrounding environment. The Ammonia Concentration and Emission Simulation (ACES) model includes mechanistic sub-models to describe the urination frequency and location, the ammonia emission from individual urine puddles, and the ammonia emission from slurry. Data were collected from two grower-finisher rooms to use as input data to the model and for calibration and validation purposes. The model allows for hourly simulations for up to a 3-day period from mechanically ventilated swine barns for a variety of housing configurations and production variables.

Dynamic Simulation of Ammonia Concentration and Emission within Swine Barns: Part II. Model Calibration and Validation

The ventilation and environmental control parameters of two broiler houses were measured and monitored in California at one site of the National Air Emissions Monitoring Study. This article presents the ventilation measurement results from 15 November 2007 to 13 September 2009, which covered 12 broiler production cycles. The duration of each cycle was about 45 d for raising new chicks to 2.7 kg market-size birds. The two broiler houses had identical structural designs and ventilation, feeding, and litter management practices. Each house contained about 21,000 broilers in each production cycle and was mechanically ventilated with eleven fans, including one 91 cm fan and ten 122 cm fans. All the fans, heaters, and evaporative cooling systems were automatically operated to control the house temperature from 32°C at the beginning to 18°C at the end of each production cycle. The environmental parameters that were monitored included temperature, relative humidity, and static pressure inside the houses, and ambient temperature, relative humidity, wind speed and direction, and solar radiation outside the houses. The operational status and rotational speed of all ventilation fans were continuously monitored. The ventilation rate of each house was estimated by calculating the airflow rate through all the fans based on the static pressure difference in the building, fan performance, and operation status. The production cycle average daily mean ventilation rate was correlated with the cycle average daily mean ambient temperature. The ventilation rate for any day within a cycle was influenced primarily by bird age and ambient temperature. The daily ventilation rate ranged from 0.14 to 11.5 m3 h-1 bird-1, and the average rate was 2.8 m3 h-1 bird-1. The minimum and maximum ventilation rates occurred in January and July-August, respectively. Average ventilation volume per broiler during a growth cycle was 2981 m3. Ventilation rate was successfully correlated with chicken age and ambient temperature. Fan usage averaged 21% and ranged from 13% to 61% of total time for this ventilation management scheme.

Assessing the Performance of Hydrogen Sulfide Monitoring Devices and a Water Spray Method to Reduce Worker Exposure in Swine Buildings

Model calibration and validation are critical components in developing a useful model for simulating ammonia production in grower-finisher swine barns. Data were collected from two partially slatted grower-finisher rooms to use as input data to the Ammonia Concentration and Emission Simulation (ACES) model and for calibration and validation purposes. Ten 3-day data sets were used during calibration of the volatile fraction of total ammoniacal nitrogen in the slurry, the air exchange rate through the slatted floor, the fouled floor area, and the urease activity factor. The remaining twenty 3-day data sets were used during model validation. The biases in the ACES simulations for hourly room and pit headspace ammonia concentrations were -1% and 10%, respectively, and 2% and 11% for 3-day average concentrations in the room and pit headspace areas, respectively. The ACES model and data collected suggest that the emission from urine puddles on the floor surface can account for the majority (>95%) of total ammonia emission from a room with low (<7) slurry pH properties.

Measuring and simulating the urination frequency of grower-finisher pigs

A spray treatment method was evaluated for reducing worker exposure to hydrogen sulfide (H2S). Additionally, the performance of commercial H2S monitoring devices was verified by comparing readings with a reference analytical method using a gas chromatograph. Results showed that the H2S monitors yielded readings that were in close agreement with those from the reference method. Additionally, spraying with water was effective in reducing the levels of H2S released from agitated manure, although an initial increase in H2S levels was observed at the start of spray application. An additive mixed with spray water did not help in reducing H2S levels.