Albert J. Heber

Quality assured measurements of animal building emissions: Odor concentrations

Abstract Standard protocols for sampling and measuring odor emissions from livestock buildings are needed to guide scientists, consultants, regulators, and policy-makers. A federally funded, multistate project has conducted field studies in six states to measure emissions of odor, coarse particulate matter (PM10), total suspended particulates, hydrogen sulfide, ammonia, and carbon dioxide from swine and poultry production buildings. The focus of this paper is on the intermittent measurement of odor concentrations at nearly identical pairs of buildings in each state and on protocols to minimize variations in these measurements. Air was collected from pig and poultry barns in small (10 L) Tedlar bags through a gas sampling system located in an instrument trailer housing gas and dust analyzers. The samples were analyzed within 30 hr by a dynamic dilution forced-choice olfactometer (a dilution apparatus). The olfactometers (AC’SCENT International Olfactometer, St. Croix Sensory, Inc.) used by all participating laboratories meet the olfactometry standards (American Society for Testing and Materials and European Committee for Standardization [CEN]) in the United States and Europe. Trained panelists (four to eight) at each laboratory measured odor concentrations (dilution to thresholds [DT]) from the bag samples. Odor emissions were calculated by multiplying odor concentration differences between inlet and outlet air by standardized (20 °C and 1 atm) building airflow rates.

EFFECTS OF MANURE REMOVAL STRATEGIES ON ODOR AND GAS EMISSIONS FROM SWINE FINISHING

Odor, ammonia (NH3) and hydrogen sulfide (H2S) concentrations, and emission rates were measured in two small rooms of finishing pigs with various manure removal strategies. The strategies included daily flush, and static pits with 7, 14, and 42 d manure accumulation cycles, with and without pit recharge with some secondary lagoon effluent after emptying. In each room, tests were conducted with three successive groups of 25 pigs, which were fed standard corn-soybean diets. Ammonia and H2S concentrations were measured automatically 15 to 24 times daily at various locations with chemiluminescence and pulsed fluorescence analyzers, respectively. Odor concentration, intensity, and hedonic tone of air samples were evaluated by a panel of eight trained subjects. Flushing and static pit recharge with lagoon effluent resulted in significantly less NH3, H2S, and odor emissions (P < 0.05). Draining static pits more frequently also significantly reduced H2S and odor emissions. Geometric mean odor emission rates were 19, 33, and 29 OUE s-1 AU-1 (OUE = European odor unit equivalent to 123 .g n-butanol, AU = 500 kg live mass) for the 1 d (daily flush), 7 d, and 14 d cycles without pit recharge, respectively, and 2.6 and 25 OUE s-1 AU-1 for the 7 d and 42 d cycles with pit recharge, respectively. Mean NH3 emission rates were 15, 27, and 25 g d-1 AU-1 for the 1, 7, and 14 d cycles without pit recharge, and 10, 12 and 11 g d-1 AU-1 for the 7, 14, and 42 d cycles with pit recharge, respectively. Mean H2S emission rates were 0.11, 0.27, and 0.41 g d-1 AU-1 for the 1, 7, and 14 d cycles without pit recharge, and 0.16, 0.34, and 1.42 g d-1 AU-1 for the 7, 14, and 42 d cycles with pit recharge, respectively. The mean H2S emission rate during daily flushing was 0.40 g d-1 AU-1 when flushing-induced burst emissions were included in the means, as compared with 0.11 g d-1 AU-1 when flushing times were excluded. Sudden emissions during flushing events had a significant influence on mean emissions from these relatively small rooms; however, without valid data from week 1, the mean H2S emission rate of 0.40 g d-1 AU-1 was probably an overestimate. Daily flushing reduced odor emissions by 41% and 34% (P < 0.05) as compared with the 7 d and 14 d cycles, respectively. The 7 d cycle resulted in 35% and 53% lower H2S emissions as compared with the 14 d cycle with and without pit recharge, respectively. The 14 d cycle had 76% less (P < 0.05) H2S emission than the 42 d cycle, both cycles with pit recharge. Mean daily NH3 emissions from the rooms with static pits were 51% to 62% lower (P < 0.05) with recharge than without recharge. Similarly, mean daily H2S emissions were 18% to 40% lower with pit recharge. In summary, lower NH3 and H2S emissions occurred when pits were recharged after emptying, and when pits were emptied more frequently.

Sampling and Measurement of Ammonia at Animal Facilities

Scientific understanding and technical control of ammonia (NH3) at animal facilities, including animal buildings, feedlots, manure storages, and manure treatment plants, depend on reliable sampling and measurement techniques to ensure high quality data that are essential to the study and abatement of NH3 emission. This chapter focuses on the methodology and technology of NH3 sampling and measurement that has been tested or applied under field conditions since the 1960s. It draws a comprehensive and updated picture of the state of the art of NH3 concentration measurement at animal facilities. Ammonia sampling requires selection of location, time, and/or control of sample volume. Three sampling methods, the closed, point, and open-path methods, are summarized. Thirty-one measurement instruments/sensors are identified. They are categorized in nine groups and evaluated according to their technical characteristics. Field studies or applications of these instruments/sensors are reviewed and summarized. Principles, procedures, advantages, and disadvantages of various sampling and measurement techniques are discussed. An overview of data and data quality is provided. Errors resulted from calibration, sampling, measurement, and data processing are discussed. Error reduction methods are presented. Recommendations are made for selection of sampling methods and measurement devices and for future needs including development of methodologies and standards.

Volatile organic compounds at swine facilities: A critical review

Volatile organic compounds (VOCs) are regulated aerial pollutants that have environmental and health concerns. Swine operations produce and emit a complex mixture of VOCs with a wide range of molecular weights and a variety of physicochemical properties. Significant progress has been made in this area since the first experiment on VOCs at a swine facility in the early 1960s. A total of 47 research institutions in 15 North American, European, and Asian countries contributed to an increasing number of scientific publications. Nearly half of the research papers were published by U.S. institutions. Investigated major VOC sources included air inside swine barns, in headspaces of manure storages and composts, in open atmosphere above swine wastewater, and surrounding swine farms. They also included liquid swine manure and wastewater, and dusts inside and outside swine barns. Most of the sample analyses have been focusing on identification of VOC compounds and their relationship with odors. More than 500 VOCs have been identified. About 60% and 10% of the studies contributed to the quantification of VOC concentrations and emissions, respectively. The largest numbers of VOC compounds with reported concentrations in a single experimental study were 82 in air, 36 in manure, and 34 in dust samples. The relatively abundant VOC compounds that were quantified in at least two independent studies included acetic acid, butanoic acid (butyric acid), dimethyl disulfide, dimethyl sulfide, iso-valeric, p-cresol, propionic acid, skatole, trimethyl amine, and valeric acid in air. They included acetic acid, p-cresol, iso-butyric acid, butyric acid, indole, phenol, propionic acid, iso-valeric acid, and skatole in manure. In dust samples, they were acetic acid, propionic acid, butyric acid, valeric acid, p-cresol, hexanal, and decanal. Swine facility VOCs were preferentially bound to smaller-size dusts. Identification and quantification of VOCs were restricted by using instruments based on gas Chromatography (GC) and liquid chromatography (LC) with different detectors most of which require time-consuming procedures to obtain results. Various methodologies and technologies in sampling, sample preparation, and sample analysis have been used. Only four publications reported using GC based analyzers and PTR-MS (proton-transfer-reaction mass spectrometry) that allowed continuous VOC measurement. Because of this, the majority of experimental studies were only performed on limited numbers of air, manure, or dust samples. Many aerial VOCs had concentrations that were too low to be identified by the GC peaks. Although VOCs emitted from swine facilities have environmental concerns, only a few studies investigated VOC emission rates, which ranged from 3.0 to 176.5mgd(-1)kg(-1) pig at swine finishing barns and from 2.3 to 45.2gd(-1)m(-2) at manure storages. Similar to the other pollutants, spatial and temporal variations of aerial VOC concentrations and emissions existed and were significantly affected by manure management systems, barn structural designs, and ventilation rates. Scientific research in this area has been mainly driven by odor nuisance, instead of environment or health concerns. Compared with other aerial pollutants in animal agriculture, the current scientific knowledge about VOCs at swine facilities is still very limited and far from sufficient to develop reliable emission factors.

Ammonia emission model for whole farm evaluation of dairy production systems.

Ammonia (NH) emissions vary considerably among farms as influenced by climate and management. Because emission measurement is difficult and expensive, process-based models provide an alternative for estimating whole farm emissions. A model that simulates the processes of NH formation, speciation, aqueous-gas partitioning, and mass transfer was developed and incorporated in a whole farm simulation model (the Integrated Farm System Model). Farm sources included manure on the floor of the housing facility, manure in storage (if used), field-applied manure, and deposits on pasture (if grazing is used). In a comprehensive evaluation of the model, simulated daily, seasonal, and annual emissions compared well with data measured over 2 yr for five free stall barns and two manure storages on dairy farms in the eastern United States. In a further comparison with published data, simulated and measured barn emissions were similar over differing barn designs, protein feeding levels, and seasons of the year. Simulated emissions from manure storage were also highly correlated with published emission data across locations, seasons, and different storage covers. For field applied manure, the range in simulated annual emissions normally bounded reported mean values for different manure dry matter contents and application methods. Emissions from pastures measured in northern Europe across seasons and fertilization levels were also represented well by the model. After this evaluation, simulations of a representative dairy farm in Pennsylvania illustrated the effects of animal housing and manure management on whole farm emissions and their interactions with greenhouse gas emissions, nitrate leaching, production costs, and farm profitability.

Air Quality Monitoring and On-Site Computer System for Livestock and Poultry Environment Studies

This article reviews the development of agricultural air quality (AAQ) research on livestock and poultry environments, summarizes various measurement and control devices and the requirements of data acquisition and control (DAC) for comprehensive AAQ studies, and introduces a new system to meet DAC and other requirements. The first experimental AAQ study was reported in 1953. Remarkable progress has been achieved in this research field during the past decades. Studies on livestock and poultry environment expanded from indoor air quality to include pollutant emissions and the subsequent health, environmental, and ecological impacts beyond the farm boundaries. The pollutants of interest included gases, particulate matter (PM), odor, volatile organic compounds (VOC), endotoxins, and microorganisms. During this period the research projects, scales, and boundaries continued to expand significantly. Studies ranged from surveys and short-term measurements to national and international collaborative projects. While much research is still conducted in laboratories and experimental facilities, a growing number of investigations have been carried out in commercial livestock and poultry farms. The development of analytical instruments and computer technologies has facilitated significant changes in the methodologies used in this field. The quantity of data obtained in a single project during AAQ research has increased exponentially, from several gas concentration samples to 2.4 billion data points. The number of measurement variables has also increased from a few to more than 300 at a single monitoring site. A variety of instruments and sensors have been used for on-line, real-time, continuous, and year-round measurements to determine baseline pollutant emissions and test mitigation technologies. New measurement strategies have been developed for multi-point sampling. These advancements in AAQ research have necessitated up-to-date systems to not only acquire data and control sampling locations, but also monitor experimental operation, communicate with researchers, and process post-acquisition signals and post-measurement data. An on-site computer system (OSCS), consisting of DAC hardware, a personal computer, and on-site AAQ research software, is needed to meet these requirements. While various AAQ studies involved similar objectives, implementation of OSCS was often quite variable among projects. Individually developed OSCSs were usually project-specific, and their development was expensive and time-consuming. A new OSCS, with custom-developed software AirDAC, written in LabVIEW, was developed with novel and user-friendly features for wide ranging AAQ research projects. It reduced system development and operational cost, increased measurement reliability and work efficiency, and enhanced quality assurance and quality control in AAQ studies.

Odor and Odorous Chemical Emissions from Animal Buildings: Part 6. Odor Activity Value

There is a growing concern with air and odor emissions from agricultural facilities. A supplementary research project was conducted to complement the U.S. National Air Emissions Monitoring Study (NAEMS). The overall goal of the project was to establish odor and chemical emission factors for animal feeding operations. The study was conducted over a 17-month period at two freestall dairies, one swine sow farm, and one swine finisher facility. Samples from a representative exhaust airstream at each barn were collected in 10 L Tedlar bags and analyzed by trained human panelists using dynamic triangular forced-choice olfactometry. Samples were simultaneously analyzed for 20 odorous compounds (acetic acid, propanoic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, hexanoic acid, heptanoic acid, guaiacol, phenol, 4-methylphenol, 4-ethylphenol, 2-aminoacetophenone, indole, skatole, dimethyl disulfide, diethyl disulfide, dimethyl trisulfide, hydrogen sulfide, and ammonia). In this article, which is part 6 of a six-part series summarizing results of the project, we investigate the correlations between odor concentrations and odor activity value (OAV), defined as the concentration of a single compound divided by the odor threshold for that compound. The specific objectives were to determine which compounds contributed most to the overall odor emanating from swine and dairy buildings, and develop equations for predicting odor concentration based on compound OAVs. Single-compound odor thresholds (SCOT) were statistically summarized and analyzed, and OAVs were calculated for all compounds. Odor concentrations were regressed against OAV values using multivariate regression techniques. Both swine sites had four common compounds with the highest OAVs (ranked high to low: hydrogen sulfide, 4-methylphenol, butyric acid, isovaleric acid). The dairy sites had these same four compounds in common in the top five, and in addition diethyl disulfide was ranked second at one dairy site, while ammonia was ranked third at the other dairy site. Summed OAVs were not a good predictor of odor concentration (R2 = 0.16 to 0.52), underestimating actual odor concentrations by 2 to 3 times. Based on the OAV and regression analyses, we conclude that hydrogen sulfide, 4-methylphenol, isovaleric acid, ammonia, and diethyl disulfide are the most likely contributors to swine odor, while hydrogen sulfide, 4-methyl phenol, butyric acid, and isovaleric acid are the most likely contributors to dairy odors.

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).

Biofiltration of a mixture of ethylene, ammonia, n-butanol, and acetone gases.

This study describes cleaning of a waste gas stream using bench scale biofilters (BFs) or biotrickling filters (BTFs). The gas stream contained a mixture of acetone, n-butanol, methane, ethylene, and ammonia, and was diverted uniformly to six biofilters and four biotrickling filters. The biofilters were packed with either perlite (BF-P), polyurethane foam (BF-F), or a mixture of compost, wood chips, and straw (BF-C), whereas the biotrickling filters contained either perlite (BTF-P) or polyurethane foam (BTF-F). Experimental results showed that both BFs and BTFs packed with various media were able to achieve complete removal of highly soluble compounds such as acetone, n-butanol, and ammonia of which the dimensionless Henrys constants (H) are less than 0.01. Methane was not removed due to its extreme insolubility (H>30). However, the ethylene (H ≈ 9) removal efficiencies depended on trickle water flow rates, media surface areas, and ammonia gas levels.

Real-Time Airflow Rate Measurements from Mechanically Ventilated Animal Buildings

Abstract This paper describes techniques used to determine airflow rate in multiple emission point applications typical of animal housing. An accurate measurement of building airflow rate is critical to accurate emission rate estimates. Animal housing facilities rely almost exclusively on ventilation to control inside climate at desired conditions. This strategy results in building airflow rates that range from about three fresh-air changes per hour in cold weather to more than 100 fresh-air changes per hour in hot weather. Airflow rate measurement techniques used in a comprehensive six-state study could be classified in three general categories: fan indication methods, fan rotational methods, and airspeed measurement methods. Each technique is discussed and implementation plans are noted. A detailed error analysis is included that estimated the uncertainty in airflow rate between ±5 and ±6.1% of reading at a building operating static pressure, air temperature, relative humidity, and barometric pressure of 20 Pa, 25 °C, 50%, and 97,700 Pa, respectively.