David B. Beasley

ANSWERS: A Model for Watershed Planning

ABSTRACT IN recent years, a greatly increased emphasis has been placed on improving and maintaining the quality of our national water resources. Agencies and individuals from the various levels of government, industry and private life are seeking information concerning the ef-fects that land use, management, and conservation prac-tices or structures might have on the quality and quantity of water from both agricultural and non-agricultural watersheds. ANSWERS (Areal Nonpoint Source Watershed En-vironment Response Simulation) was developed in an ef-fort to supply the desired information described above for primarily agricultural watersheds. The overall struc-ture consists of a hydrologic model, a sediment detachment/transport model and several routing com-ponents necessary to describe the movement of water in overland, subsurface and channel flow phases. ANSWERS, unlike many large-scale watershed model structures, uses distributed (rather than lumped) parameters and is event (rather than long-term) oriented. These operational features generally yield a better understanding of the hydrologic and water quality interactions involved in a watershed by allowing the user to physically describe those processes both spatially and temporally. The purpose of this report is to present the operational concepts, the basic mathematical model used in ANSWERS, general data needs and user considerations. In addition, the potential utility of ANSWERS as a plan-ning tool is demonstrated by simulating several manage-ment alternatives for a primarily agricultural watershed in northeastern Indiana subjected to several different precipitation events.

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.

Emissions of Ammonia, Hydrogen Sulfide, and Odor before, during, and after Slurry Removal from a Deep-Pit Swine Finisher

Abstract It is a common practice in the midwestern United States to raise swine in buildings with under-floor slurry storage systems designed to store manure for up to one year. These so-called “deep-pit” systems are a concentrated source for the emissions of ammonia (NH3), hydrogen sulfide (H2S), and odors. As part of a larger six-state research effort (U.S. Department of Agriculture-Initiative for Future Agriculture and Food Systems Project, “Aerial Pollutant Emissions from Confined Animal Buildings”), real-time NH3 and H2S with incremental odor emission data were collected for two annual slurry removal events. For this study, two 1000-head deep-pit swine finishing facilities in central Iowa were monitored with one-year storage of slurry maintained in a 2.4 m-deep concrete pit (or holding tank) below the animal-occupied zone. Results show that the H2S emission, measured during four independent slurry removal events over two years, increased by an average of 61.9 times relative to the before-removal H2S emission levels. This increase persisted during the agitation process of the slurry that on average occurred over an 8-hr time period. At the conclusion of slurry agitation, the H2S emission decreased by an average of 10.4 times the before-removal emission level. NH3 emission during agitation increased by an average of 4.6 times the before-removal emission level and increased by an average of 1.5 times the before-removal emission level after slurry removal was completed. Odor emission increased by a factor of 3.4 times the before-removal odor emission level and decreased after the slurry-removal event by a factor of 5.6 times the before-removal emission level. The results indicate that maintaining an adequate barn ventilation rate regardless of animal comfort demand is essential to keeping gas levels inside the barn below hazardous 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.

The ABCs of preparing for ABET

For an undergraduate biomedical engineering (BME) degree program to gain accreditation, it must pass a thorough evaluation by the Accreditation Board for Engineering and Technology, Inc. (ABET). ABET is the organization responsible for monitoring, evaluating, and certifying the quality of engineering, engineering technology, and engineering-related education in the United States. This article provides guidance on planning, implementing, and accrediting BME programs. New programs are generally not as well connected to a previous infrastructure and an information database needed for the review process. Existing programs usually have a mindset and history for doing the pre-EC2000 preparation, which can also cause significant problems. Each author is a fully trained ABET evaluator and offers insights gained from experience on how to achieve a successful conclusion without providing any details about any programs visited.

Modeling Ammonia Emissions from Broiler Litter at Laboratory Scale

The objectives of this study were to develop a mechanistic emission model to estimate ammonia flux from broiler litter and to evaluate the model at laboratory scale. In the proposed model, the ammonia flux is essentially a function of the litters total ammoniacal nitrogen (TAN) content, moisture content, pH, and temperature, as well as the Freundlich partition coefficient (Kf), mass transfer coefficient (KG), ventilation rate (Q), and emission surface area (A). The Freundlich partition coefficient (Kf) was used as a fitting parameter in the model. A dynamic flow-through chamber system and a wind tunnel were designed to measure ammonia fluxes from broiler litter. The dynamic flow-through chamber experiments evaluated the proposed model with various litter samples under a constant temperature and wind profile. The wind tunnel experiments evaluated the proposed model under various temperatures and wind profiles. Model parameters such as Kf and KG were estimated. The results from the two experiments were consistent with each other. The estimated KG ranged from 1.11 to 27.64 m h-1, and the estimated Kf ranged from 0.56 to 4.48 L kg-1. A regression sub-model was developed to estimate Kf as function of litter pH and temperature, which indicated that Kf increased with increasing litter pH and decreased with increasing temperature. The proposed model was used to estimate the equilibrium gas phase ammonia concentration (Cg,0) in litter, and the model-predicted values were compared with the observed values. The normalized mean error (NME), the normalized mean square error (NMSE), and fractional bias (FB) were calculated to be 25%, 12%, and -0.3%, respectively, for all 94 measurements, and the model was able to reproduce 80% of the variability of the data. Sensitivity analysis of the model showed that ammonia flux is very sensitive to litter pH and to a lesser extent temperature. The relative sensitivity of pH or temperature increases as the pH or temperature increases.

Comparison of Measured Total Suspended Particulate Matter Concentrations Using Tapered Element Oscillating Microbalance and a Total Suspended Particulate Sampler

Abstract A comparison of the concentration of the total suspended particulate (TSP) matter measured by the tapered element oscillating microbalance (TEOM) monitor and the isokinetic TSP samplers developed at the University of Illinois was carried out in several types of confinement livestock buildings. In a majority of the measurements done, the dust concentration measured by the TEOM monitor was lower than the University of Illinois at Urbana-Champaign (UIUC) isokinetic TSP sampler; the TEOM monitor tended to underestimate the total dust concentration by as much as 54%. The difference in measurements can be attributed to the sampling efficiency of the TEOM monitor sampling head and the loss of some semivolatile compounds and particle-bound water because of heating of the TEOM monitor sampling stream to 50 °C. Although several articles in the literature supported the latter argument, this study did not investigate the effect of heating the sampling stream or the effect of moisture on the relative difference in dust concentration measurements. The model that best describes the relationship between the two methods was site specific, that is, the linear regression model was applicable only to four of the sites monitored. The measured total dust concentration in livestock buildings range from ∼300 to 4000 μg/m3; a higher correlation coefficient between TEOM-TSP and UIUC-TSP monitors was obtained in swine facilities than those obtained in a laying facility.

A Review of Emission Models of Ammonia Released from Broiler Houses

Over the last ten years, animal feeding operations (AFOs) have expanded greatly. As a component of animal waste, immeasurable ammonia is released. In both Europe and the United States, the largest source of ammonia emissions is animal production. With increasingly stringent federal and state air pollution regulations and the emerging pressure to regulate agricultural enterprises, ammonia emissions from animal production have become an increasing concern to regulators, producers, and environmental groups in the United States. However, efforts to regulate these emissions have been confounded by a lack of information. One of the technical challenges is the need for modeling the process of ammonia emissions from animal feeding operations. Broiler houses are one aspect of agriculture that is of particular interest to regulators and environmental groups. In recent publications, various models have been proposed to estimate ammonia emissions from broiler houses. These models are diversified in their structures and applications. It appears that a comprehensive review of theses available models would be of benefit to research in this field. This paper summarizes the scientific basis of ammonia emissions from broiler litter and the major factors that may influence ammonia emissions. The theoretical principles and the structures of the models are generalized. These models improved understanding of the physical and chemical processes of ammonia release, and can be useful to improve the accuracy and simplicity in estimating ammonia emissions from broiler houses. The current technical challenges and future direction of developments are discussed.

Real-Time Ventilation Measurements from Mechanically Ventilated Livestock Buildings for Emission Rate Estimations

A six-state USDA-IFAFS funded research project (Aerial Pollutant Emissions from Confined Animal Buildings, APECAB) was conducted with the purpose of determining hydrogen sulfide, ammonia, PM10, and odor emission rates from selected swine and poultry housing systems. An important aspect of emission studies is to be able to measure the mass flow rate of air through the housing system. For this research project, the decision was made to study only fan ventilated buildings due to the difficulty in estimated mass flow rates through naturally ventilated buildings. This paper highlights the various techniques used throughout the study to determine mass flow rate through fan ventilated swine and poultry housing systems.

Particle Size Distribution of Particulate Matter Emitted from a Layer Operation in Southeast U.S.

This paper reports a field study on characterizing particle size distribution (PSD) of particulate matter (PM) emitted from a commercial layer operation in Southeast U.S. across three seasons from October of 2008 to April of 2009. Six low-volume (1m3/hr) total suspended particulate (TSP) samplers were used to collect PM samples in two high-rise layer houses. Laser diffraction particle size analyzer (LS13 320) was applied to measure PSD of PM samples collected by the TSP samplers. Results of the study indicate that TSP concentrations across the three seasons ranged from 888 to 5333 µg/m3. TSP concentration was affected by season, animal activity, floor and equivalent air flow rate factor. It was observed that TSP concentration in winter was higher than that in spring; concentration on the second floor was higher than that on the first floor; the more active the animals were, the higher the TSP concentration; the more the fans on, the lower the concentration. Compared with PM concentration, PSD (characterized by the mass medium diameter, MMD, & geometric standard deviation, GSD) was much less affected by season, animal activity, floor and equivalent flow rate factor. The MMD was affected by floor and equivalent flow rate factor, but the degree of affection was within the range of one standard deviation. Overall MMDs of PM samples collected in fall, winter and spring were 15.80±1.05µm, 17.13±0.81µm and 18.44±1.44µm, respectively. The difference of MMD among three seasons was within the range of one standard deviation. GSD was relatively constant and not affected by those factors. The overall GSD was 2.65±0.08.