George B Day

Moisture Effects on Greenhouse Gases Generation in Nitrifying Gas-Phase Compost Biofilters

Gas-phase compost biofilters are extensively used in concentrated animal feeding operations to remove odors and, in some cases, ammonia from air sources. The expected biochemical pathway for these predominantly aerobic systems is nitrification. However, non-uniform media with low oxygen levels can shift biofilter microbial pathways to denitrification, a source of greenhouse gases. Several factors contribute to the formation of anoxic/anaerobic zones: media aging, media and particle structure, air velocity distribution, compaction, biofilm thickness, and moisture content (MC) distribution. The present work studies the effects of media moisture conditions on ammonia (NH(3)) removal and greenhouse gas generation (nitrous oxide, N(2)O and methane, CH(4)) for gas-phase compost biofilters subject to a 100-day controlled drying process. Continuous recordings were made for the three gases and water vapor (2.21-h sampling cycle, each cycle consisted of three gas species, and water vapor, for a total of 10,050 data points). Media moisture conditions were classified into three corresponding media drying rate (DR) stages: Constant DR (wetter media), falling DR, and stable-dry system. The first-half of the constant DR period (0-750 h; MC=65-52%, w.b.) facilitated high NH(3) removal rates, but higher N(2)O generation and no CH(4) generation. At the drier stages of the constant DR (750-950 h; MC=52-48%, w.b.) NH(3) removal remained high but N(2)O net generation decreased to near zero. In the falling DR stage (1200-1480 h; MC=44-13%) N(2)O generation decreased, CH(4) increased, and NH(3) was no longer removed. No ammonia removal or greenhouse gas generation was observed in the stable-dry system (1500-2500 h; MC=13%). These results indicate that media should remain toward the drier region of the constant DR (in close proximity to the falling DR stage; MC=50%, approx.), to maintain high levels of NH(3) removal, reduced levels of N(2)O generation, and nullify levels of CH(4) generation.

Assessment of an injectable RFID temperature sensor for indication of horse well-being

This research investigated the performance and placement of an injectable radio frequency identification (RFID) and temperature sensor to monitor the body temperature of horses. Eleven sensors were calibrated to assess reliability (accuracy and repeatability) of the temperature readings. Results of four separate calibration trials demonstrated significant variability in both accuracy and repeatability. To quantify accuracy, the regression standard errors (SE) were placed into four performance categories: 4, 0, 2 and 3 excellent (SE = 0.5°C); 2, 1, 7, and 1 good (0.5°C < SE = 0.75°C); 2, 3, 0, and 7 marginal (0.75oC < SE = 1.0°C); and 3, 7, 2, 0 poor (SE < 1.0oC) sensors in each of the performance categories for the four calibration trials, respectively. Three of the eleven sensors evaluated were found to be repeatable, however, with marginal accuracy. Based on these results it is recommended that the temperature system be calibrated before use.

Automated harvesting of Burley tobacco I. System development.

ABSTRACT A fully automated system for harvesting and handling mature buriey tobacco has been developed. This article identifies the operations essential to this harvesting concept and describes the development of the mechanisms by which they were accomplished. The system detaches, inverts and places mature plants into portable holders for air curing under waterproof covering without requiring any manual handling of the crop. Manual labor currently required to harvest buriey tobacco would be reduced by 80-85% and the system would eliminate the drudgery associated with manual handling. The harvesting system has an approximate capacity of 1.4 to 2.0 ha/day (3.5 to 5.0 ac/day) and is operated by two workers.

Biofilter Media Characterization Using Water Sorption Isotherms

Compost material has been used extensively as a gas-phase biofilter media for contaminant gas treatment in recent years. One of the biggest challenges in the use of this type of material is adequate control of compost moisture content and understanding its effect on the biofiltration process. The present work provides a methodology for characterization of biofilter media under low moisture conditions. Results indicated that low levels of equilibrium moisture content (EMC) were obtained for high levels of equilibrium relative humidity (ERH), i.e., 99% ERH produced EMC of approximately 20% (dry basis) at 25°C. Most bacteria struggle to survive in environments with ERH levels lower than 95%. Compost material from the same source was sieved into four compost particle size (PS) ranges to evaluate its water sorption behavior: 4.76 mm > PS1 > 3.36�mm > PS 2 > 2.38 mm > PS3 > 2.00 mm > PS4 > 1.68 mm. Observed data were tested against isotherm models for their goodness-of-fit. Seven isotherm models were compared: (1) Langmuir; (2) Freundlich; (3) Sips; (4) Brunauer, Emmett, and Teller (BET); (5) BET for n-layers; (6) Guggenheim, Anderson, de Boer (GAB); and (7) Henderson. In comparison with the other models, the Henderson model provided the best fit, as determined by the best combination of regression coefficient standard errors () and coefficients of determination (r 2 ) for all four particle size ranges tested (95% confidence interval, C.I., and prediction interval, P.I.). The Henderson model was then used to test for significant differences in isotherms by particle size ranges. The four tested particle size ranges were not significantly different from each other (p < 0.05), indicating similar water sorption behavior. Data from all four particle size ranges were pooled and regressed, and the minimum required moisture to maintain ERH at or above 95% was 16.41% ±2.68% (dry basis).

Assessment of an Injectable RFID Temperature Sensor for Indication of Horse Well-Being

This study investigated an injectable radio frequency identification (RFID) and temperature sensor (TX1400 B, Digital Angel, Inc., St. Paul, MN-USA). The sensor is implanted into the neck and used to measure temperature and a unique identity code.

Assessment of Biofilter Media Particle Sizes for Removing Ammonia

With increased concerns over odor and gas emissions from livestock production facilities more efficient technologies of air pollution control are needed to mitigate the deleterious effects of air contaminants. Gas-phase biofilters for treating contaminant gases from poultry and livestock operations can be cost-effective and environmentally friendly. However, a biofilter’s media is an important factor to be considered when in its design. The goal of this study was to assess three compost biofilter particle sizes (12.5 mm > R1 > 8.0 mm > R2 > 4.75 mm > R3 > 1.35 mm) for ammonia (NH3) removal efficiency and pressure drop using three different residence times (5 s, 10 s, and 20 s). The three compost particle size ranges were physically and chemically characterized, their capability to reduce NH3 was analyzed, and their resistance to airflow was determined. Accumulation of ammonium (NH4) and production of nitrite (NO2) were observed after running NH3 through the media continuously for nine days. The combination of the highest airflow rate (5 s residence time) and largest particle size range (R1) achieved higher NH3 removal efficiencies: 33.4 ± 5.7% and 35.8 ± 5.8%, respectively and the third highest pressure drop: 173.4 ± 16.4 Pa/m. The interaction between medium airflow rate (10 s residence time) and large particle size range (R1) yielded the highest NH3 removal efficiency: 36.7 ± 6.2 % and the third lowest pressure drop: 50.2 ± 7.0 Pa/m. These results were found over a start-up period of nine days.

Contaminant gas Generation as Product of Degraded Ammonia during Biofiltration

Biofiltration technology is widely utilized for treatment of ammonia gas, with one of its potential detrimental by-products being nitrous oxide, a powerful greenhouse gas. The present work intends to provide the relation between ammonia elimination capacity during biofiltration and nitrous oxide generation as product of incomplete denitrification. Four laboratory scale tubular biofilters in up flow mode (3 replicates receiving humidified air and ammonia and 1 control receiving only humidified air) will be studied and compared for three levels of ammonia volumetric loadings (4.8, 7.2, and 9.6 g m-3 h-1). Trends from the obtained ammonia and nitrous oxide relation in the laboratory will be evaluated for significance of nitrous oxide production under varied ammonia loadings.

DESIGN OF A BIOFILTER FOR SWINE WASTE FACILITY

A biofilter was designed and constructed for odor abatement of the headspace above slurry in manure holding tanks at the Swine Research Unit (SRU) at the University of Kentucky Woodford County Animal Research Center. The SRU consists of separate animal facilities, covered manure storage tanks and manure handling capabilities. The main objective of the biofilter design is to substantially reduce potential odor emissions, specifically to prevent fugitive odors from offending neighbors. Additionally, the reduction and treatment of the headspace gases will improve worker safety at the facility. Criteria for the biofilter design include robust operation, constant and consistent odor abatement for still and intermittently stirred tanks, simple maintenance and operation for the farm crew, and the capability for conducting statistically meaningful biofilter research. Design considerations include: pressure drop estimates, operating airflow estimates, fan sizing and selection, airflow handling abilities, system controls, biomass temperature and moisture control, and biofilter sizing and layout. Preliminary studies for the design investigated pressure drop through various biomass types. Also, a characterization curve was developed for maintaining static pressure differences on the headspace of each tank. Biofilter performance monitoring is the next stage of the project.

Automated Harvesting of Burley Tobacco II. Evaluation of System Performance

ABSTRACT A prototype system for fully automated harvesting of burley tobacco has been developed and tested. Three years of field testing has shown that mechanical losses associated with the system were only slightly higher than via conventional methods. The system performed reliably at a sustained harvesting rate of approximately 1.4 ha/day (3.4 acre/day), while indicating that a rate of 2 ha/day (5 acre/day) should be easily achievable. The system is operated by two workers and reduces conventional labor requirement by approximately 80-85%.

Characterizing Physical Properties of Gas-Phase Biofilter Media

Gas-phase biofiltration is an effective technology for reduction of odors and trace-gas contaminants. Significant contributions to the technical literature regarding the characterization of biofilter media have been generated in the past two decades. Nevertheless, the information produced has not been systematically organized. The objective of this study is to demonstrate and document methods for physical characterization of gas-phase compost biofilters (GPCB). The inclusion of moisture content, compaction, and particle size effects in the determination of media bulk density and porosity, field capacity, drying rate analysis, water sorption isotherms, and resistance to airflow is demonstrated. Results indicated that: (1) higher moisture content led to about 2% reduction in porosity after compaction; (2) biofilter media sieved into three particle size ranges (12.5 mm > PSR1 > 8.0 mm > PSR2 > 4.75 mm > PSR3 > 1.35 mm) produced significantly different media field capacities, i.e., 52.8% (PSR1), 61.6% (PSR2), and 72.2% (PSR3) on a wet basis; (3) a drying rate analysis provides important information regarding media-water relations and can be potentially used for in situ indirect media moisture monitoring (as shown in previous work, changes in drying rate significantly affected ammonia removal and nitrous oxide generation); (4) the Henderson isotherm can be accurately used for dry organic media to determine the minimum moisture required for microbial activity; and finally (5) the combination of high airflow and high moisture content drastically increased pressure drop up to 65-fold (6350 Pa m-1) compared to the lowest pressure drop (98 Pa m-1). Further, the research community should integrate efforts to elaborate standard methods and protocols for physical characterization of gas-phase biofilter media before and during biofilter operation.