Ji-Qin Ni

Air quality and emission measurement methodology at swine finishing buildings

Reliable measurements of air quality and emissions at large livestock buildings with inherently large spatial and temporal variations of pollutant concentrations are relatively difficult and expensive. Appropriate methodologies for such measurements are not readily apparent and techniques and strategies vary widely. Several important technical issues need to be addressed by an air pollutant emission measurement plan. This article describes comprehensive field measurements of indoor air quality and air pollutant emissions at eight commercial swine finishing buildings. The objective of the field test was to evaluate the effect of a manure additive on concentration and emission of ammonia, hydrogen sulfide, and odor. Continuous measurements of gases, ventilation rate, building static pressure, inside and outside temperature and humidity, and wind speed and direction were conducted at four naturally–ventilated buildings and four mechanically–ventilated buildings. Air was pumped continuously from inside each building into air–sampling manifolds. One air stream was drawn from beneath the floor to assess pit headspace air concentrations. Another air stream was drawn from ventilation exhaust points to assess inside gas concentrations and building emission rates. Gas analyzers were switched between sampling manifolds on 10– to 15–min sampling intervals. Ammonia was measured with chemiluminescence NOx analyzers after conversion to nitric oxide. Hydrogen sulfide was converted to sulfur dioxide and measured with pulsed–fluorescence, sulfur dioxide analyzers. Odor samples were collected in bags and evaluated using olfactometry. Gas and odor emission rates were determined by multiplying mean gas concentrations in the exhaust air by ventilation airflow rates. Ventilation rates of naturally–ventilated buildings were estimated using sensible heat and carbon dioxide balances. Ventilation rates of mechanically–ventilated buildings were determined by monitoring wall fan operation and directly measuring airflow of some variable–speed pit fans with full–size impeller anemometers. Labor and equipment requirements, pitfalls, problems, and solutions to problems of field studies are discussed. Several recommendations for future studies of this type were developed based on experience gained during this measurement campaign.

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.

CHARACTERISTICS AND EMISSION RATES OF ODOR FROM COMMERCIAL SWINE NURSERIES

Odor emission rates and characteristics were evaluated at two commercial swine nurseries in Indiana during the months of March, April, and May. The nurseries, housing 94 to 250 pigs, were mechanically ventilated with long–term manure storage pits under wire floors. Incoming ventilation air at one of the nurseries was tempered in a heated hallway. An eight–member odor panel evaluated odor concentration with a dynamic olfactometer and odor intensity and hedonic tone at full strength. The odor concentration of incoming ventilation air ranged from 7 to 85 odor units per cubic meter (OU m–3) and averaged 18 OU m–3. It ranged from 94 to 635 OU m–3 and averaged 199 OU m–3 in the ventilation exhaust air. The mean odor emission rates of the two nurseries were 18.3 and 62.5 OU s–1 AU–1 (1.1 and 2.7 OU s–1 m–2), respectively. The overall mean odor emission rate was 34 OU s–1 AU–1 (1.8 OU s–1 m–2). The measured emission rates are expected to be lower than those that follow stringent panel sensitivity requirements not currently required by olfactometry standards in the U.S.

EFFECT OF A MANURE ADDITIVE ON AMMONIA EMISSION FROM SWINE FINISHING BUILDINGS

The effect of a commercial manure additive (Alliance®) on ammonia (NH 3 ) emissions was evaluated in commercial 1000-head grow-finish swine buildings over a six-month period. The test was conducted in two treated and two control buildings at a modern swine-finishing site consisting of nine identical buildings. Automatic spray application systems in the treated buildings intermittently sprayed the additive onto the surfaces of the below-floor manure storages. Ammonia concentrations were measured with a chemiluminescence analyzer at three location groups in each building over 7 or 12 min periods every 1.0 to 1.5 h. Pit fan airflow rates were measured continuously with impeller anemometers. Wall fan airflow rates were calculated from fan pressure/airflow curves and measured static differential pressure between indoor and outdoor air. Nearly 7,000 data subsets from 332 building-days of testing were obtained for comparing NH 3 emission rates between control and treated buildings. The mean NH 3 emission rate per AU (animal unit or 500 kg live weight) from the treated buildings (96.4 g/day·AU) was 24% (P < 0.05) lower than the control buildings. The volume of additive solution was sufficient to dilute the fresh manure by 20%, but the effect of dilution only on NH 3 emission was not measured.

A Portable System for Continuous Ammonia Measurement in the Field

A portable and relatively low-cost monitoring unit (PMU) for continuous measurement of ammonia and carbon dioxide in CAFO (poultry in particular) applications has been developed and partially compared with an EPA-approved measurement method. The PMU utilizes sampling and purging cycles to overcome the sensor saturation characteristic of electro-chemical NH3 sensors. Preliminary comparative results show that performance of the PMU is quite comparable to the sophisticated, highercost, and less portable mobile lab method. For the range of ammonia level typical of commercial poultry buildings, the PMU is expected to produce emission rate data of reasonable quality when combined with properly measured or determined building ventilation rate.

Methane and carbon dioxide emission from two pig finishing barns.

Agricultural activities are an important source of greenhouse gases. However, comprehensive, long-term, and high-quality measurement data of these gases are lacking. This article presents a field study of CH(4) and CO(2) emission from two 1100-head mechanically ventilated pig (Sus scrofa) finishing barns (B1 and B2) with shallow manure flushing systems and propane space heaters from August 2002 to July 2003 in northern Missouri. Barn 2 was treated with soybean oil sprinkling, misting essential oils, and misting essential oils with water to reduce air pollutant emissions. Only days with CDFB (complete-data-full-barn), defined as >80% of valid data during a day with >80% pigs in the barns, were used. The CH(4) average daily mean (ADM) emission rates were 36.2 +/- 2.0 g/d AU (ADM +/- 95% confidence interval; animal unit = 500 kg live mass) from B1 (CDFB days = 134) and 28.8 +/- 1.8 g/d AU from B2 (CDFB days = 131). The CO(2) ADM emission rates were 17.5 +/- 0.8 kg/d AU from B1 (CDFB days = 146) and 14.2 +/- 0.6 kg/d AU from B2 (CDFB days = 137). The treated barn reduced CH(4) emission by 20% (P < 0.01) and CO(2) emission by 19% (P < 0.01). The CH(4) and CO(2) released from the flushing lagoon effluent were equivalent to 9.8 and 4.1% of the CDFB CH(4) and CO(2) emissions, respectively. The emission data were compared with the literature, and the characteristics of CH(4) and CO(2) concentrations and emissions were discussed.

Quality-Assured Measurements of Animal Building Emissions: Particulate Matter Concentrations

Abstract Federally funded, multistate field studies were initiated in 2002 to measure emissions of particulate matter (PM) <10 μm (PM10) and total suspended particulate (TSP), ammonia, hydrogen sulfide, carbon dioxide, methane, non-methane hydrocarbons, and odor from swine and poultry production buildings in the United States. This paper describes the use of a continuous PM analyzer based on the tapered element oscillating microbalance (TEOM). In these studies, the TEOM was used to measure PM emissions at identical locations in paired barns. Measuring PM concentrations in swine and poultry barns, compared with measuring PM in ambient air, required more frequent maintenance of the TEOM. External screens were used to prevent rapid plugging of the insect screen in the PM10 preseparator inlet. Minute means of mass concentrations exhibited a sinusoidal pattern that followed the variation of relative humidity, indicating that mass concentration measurements were affected by water vapor condensation onto and evaporation of moisture from the TEOM filter. Filter loading increased the humidity effect, most likely because of increased water vapor adsorption capacity of added PM. In a single layer barn study, collocated TEOMs, equipped with TSP and PM10 inlets, corresponded well when placed near the inlets of exhaust fans in a layer barn. Initial data showed that average daily mean concentrations of TSP, PM10, and PM2.5 concentrations at a layer barn were 1440 ± 182 μg/m3 (n = 2), 553 ± 79 μg/m3 (n = 4), and 33 ± 75 μg/m3 (n = 1), respectively. The daily mean TSP concentration (n =1) of a swine barn sprinkled with soybean oil was 67% lower than an untreated swine barn, which had a daily mean TSP concentration of 1143 ± 619 μg/m3. The daily mean ambient TSP concentration (n = 1) near the swine barns was 25 ± 8 μg/m3. Concentrations of PM inside the swine barns were correlated to pig activity.