C. J. Clanton

Odor, Total Reduced Sulfur, and Ammonia Emissions from Animal Housing Facilities and Manure Storage Units in Minnesota

The quantification of odor, total reduced sulfur (TRS), and ammonia (NH3) emissions from animal housing facilities and manure storage units is essential for the development and implementation of improved setback evaluation methods and tools. This observational study measured odor, TRS, and NH3 levels emitted from more than 200 animal housing facilities and manure storage units on 85 farms in Minnesota. Emissions were highly variable in accordance with observations from other large air quality studies. Possible reasons for the large variation in emissions data included differences between sampling sites and season or ambient temperature. Odor, TRS, and NH3 emissions were typically highest from swine housing facilities and concrete tanks containing swine or dairy manure. Pearson’s correlation matrix calculated significant (p < 0.05) and strong correlations between odor and TRS emissions (r = 0.947) and odor and NH3 emissions (r = 0.954) from swine housing only. Therefore, TRS and/or NH3 emissions from swine housing facilities are potential proxies for odor emissions. This study was strictly observational and not a controlled experiment. Thus, odor TRS and NH3 emissions reported in this study may not apply to other geographic locations.

Sulfur compounds in gases emitted from stored manure

Under anaerobic conditions, organic compounds containing sulfur break down, forming intermediate sulfurcontaining compounds that ultimately form hydrogen sulfide. The objectives of this project were to determine various sulfur-containing compound concentrations in collected air and liquid samples from stored swine and dairy manure and correlate these sulfur compound concentrations with each other. Three different manure-handling/storage methods (a batch study, a semi-batch study, and a field study) generated a total of 52 paired (air and liquid) samples. Of the 20 sulfur-containing compounds detectable by the analytical laboratory, six were detected in the air samples and seven were detected in the liquid samples. None of the compounds was significantly affected by specie (swine and dairy). Concentrations of hydrogen sulfide, dimethyl sulfide, and carbon disulfide changed significantly with time. Additional research is needed to further examine the biochemical pathways in the formation of hydrogen sulfide from anaerobically stored manure.

GEOTEXTILE COVERS TO REDUCE ODOR AND GAS EMISSIONS FROM SWINE MANURE STORAGE PONDS

Odor, hydrogen sulfide (H2S), ammonia (NH3), and volatile organic compounds (VOC, GC/MS analytes) were measured between May and October 2000, and between April and October 2001 at sites representing three different swine production facilities (8000-head nursery, 2000-head finishing, and 3000-head finishing) in southwestern Minnesota. For each facility type, two farms were tested. The paired farms had similar manure storage ponds, production phases, herd sizes, genetics, and diet formulations. A manure storage pond from each pair of farms was selected as treatment (with geotextile cover, Biocap.), and the other as control (without cover). Results showed reductions in odor, H2S, and NH3 flux rates due to the geotextile cover, but performance in reducing odor and H2S deteriorated during the second year of the study. No significant differences in VOC (GC/MS analytes) emissions from covered and non-covered manure storage ponds were observed during the two-year study. Analysis of ambient H2S data suggested the covers were effective in reducing ambient H2S concentrations near manure storage ponds located at the two finishing units. Odor and gaseous flux rates were poorly correlated with relevant manure parameters (NH3 -N, sulfides, and VOC).

AMMONIA REMOVAL DURING BIOFILTRATION AS AFFECTED BY INLET AIR TEMPERATURE AND MEDIA MOISTURE CONTENT

Biofiltration is a promising technology for minimizing odor and gas emissions from livestock buildings. A laboratory experiment investigated N accumulation and N transformations to better understand how biofilters remove airborne NH3. Total-N accumulated in the media accounted for only 29% of the N removed by the biofilter after 1160 h. The fate of the remaining N is unknown. Nitric oxide (NO) gas emission accounts for only a small part (<2%) of the difference, and no N was lost via leaching. Microsite denitrification to dinitrogen (N2), nitrogen dioxide (NO2), or nitrous oxide (N2O) may explain some of the discrepancy, but further research is needed. An attempt to determine N transformation rates was not successful due to continuous modeled circular N transformations. Despite these unexplained N fates, this experiment showed that biofiltration can effectively remove NH3 levels from exhaust air.

SULFUR AND NITROGEN BALANCES IN BIOFILTERS FOR ODOROUS GAS EMISSION CONTROL

Biofiltration is a promising technology for reducing odor and gas emissions from livestock operations. Two important operating parameters in biofiltration—media moisture content (MC), and gas retention time (RT)—were studied to determine their effects on sulfur (S) and nitrogen (N) balances. Laboratory experiments were carried out to determine S and N accumulation in and emissions from biofilters with various media MC (30%, 40%, 50% wb) and RT (5, 10, 20 s). The biofilter media was a mixture of compost and wood chips. The media bed was 0.20 m deep and 0.30 m in diameter. Two trials (replications) were run. Results showed that 47% to 94% of the hydrogen sulfide (H 2 S) and 25% to 90% of the ammonia (NH 3 ) were removed by the biofilters. Removal efficiency varied with treatment. Biofilters with 50% MC and 20 s RT had the largest removal efficiencies for both H 2 S and NH 3 , with average H 2 S removal rates of 92.8% in Trial 1 and 94.2% in Trial 2. Average NH 3 removal efficiencies of these biofilters (50% MC and 20 s RT) were 90.3% in Trial 1 and 75.8% in Trial 2. S and N accumulation in the biofilter media was also affected by MC and RT. Accumulation models for S and N in the media were developed and reported.

Dynamic olfactometry variability in determining odor dilutions-to-threshold

When conducting research on odor abatement technologies, a weak link has been the inability to place a precise quantifying number on odor strength that can be accurately reproduced within the same laboratory and between laboratories. Olfactometry is one of the most accepted means for evaluating odor samples. However, insufficient effort has been made to determine variation between or among individual panelists. This study was designed to analyze three odor sample strengths over a three-day period by two odor panels, each composed of eight panelists. Three sample strengths were presented randomly to each panelist three times within each session. Whole-panel variation ranged from a 22% to 50% difference in reported odor units for the same sample, depending on sample strength. Using two different airflow rate calibrations resulted in a 9% to 28% difference in odor units for the same sample, depending on sample strength. Panelist variation ranged from 4.3- to 7.1-fold, depending on sample strength, although panelist standardization slightly reduced this variation. Sample order had no effect on odor strength determination. A learning curve for individual panelists appeared to exist, as odor unit evaluation for later observations were 3.8 and 4.1 times greater than similar evaluations for the first samples. Variation between panelists is approximately the same as variation among evaluations done by the same individual; efforts should be made to reduce both these variations. To be able to detect differences in odor concentrations between control and treatment samples, large reductions in odor concentrations with several air samples are needed to accurately detect a significant reduction in odor.

Swine manure storage covers for odor control

Twenty-one, 750-L (200 gal) polyethylene tanks were filled with swine manure. Air samples were collected 24 and 48 h after each manure addition. The samples were tested for odor strength using a dynamic olfactometer and for hydrogen sulfide concentration using a Jerome® meter. The experimental design consisted of a randomized block design containing three blocks (replications) of seven treatments. The seven treatments included no cover (control), straw mat, vegetable oil mat, straw/oil mat, clay ball mat, PVC/rubber membrane, and geotextile membrane. Statistical analysis indicated that all three main effects—cover treatment, collection period, and time after manure addition—significantly (5% level) affected odor units and hydrogen sulfide concentration. Considering all air collections, the six covers reduced odor units and hydrogen sulfide concentration at various points in the study, but not in a consistent manner. The straw mat and PVC/rubber membrane significantly reduced both odors units and hydrogen sulfide concentration consistently 24 h after manure addition during the first three collection periods. Mixing vegetable oil with straw appears to increase longevity of the cover as compared to straw only. The vegetable oil layer, when mixed with the manure, produced a distinctively offensive non-swine odor. The clay ball mat reduced emissions, although not as well as other covers. A geotextile membrane may be a possible cover choice, since the fabric is self-floating and the biofilm that grew on the mat could self-seal the cover. A straw mat (possibly including vegetable oil) and PVC/rubber membrane appear to be the most effective covers in reducing both odors and hydrogen sulfide. Oil alone should not be used as a cover.

SWINE MANURE CHARACTERIZATION AS AFFECTED BY ENVIRONMENTAL TEMPERATURE, DIETARY LEVEL INTAKE, AND DIETARY FAT ADDITION

ABSTRACT Physical, chemical, and energy characteristics of swine urine and feces were determined. Changes in urinary and fecal characteristics were determined as pigs were exposed to changes in ambient temperature, feed intake, and dietary fat concentration as well as increases in body mass. The data indicate a large variation in the characteristics of urine and feces when pigs are exposed to different environmental conditions. Fecal total solids and total volatile solids concentrations decreased as pig mass increased. Urinary total solids and total volatile solids concentrations decreased and urinary energy content increased as ambient temperature increased. Urinary NH3-N concentration was less in the fat-added diet than in the non-fat diet.

Carbon-to-Nitrogen Ratio and Hydraulic Retention Time Effect on the Anaerobic Digestion of Cheese Whey

ABSTRACT SIXTEEN 1-L digesters were used to test four carbon-to-nitrogen ratios of 8.4, 13.9, 22.2 and 27.6 and four hydraulic retention times of 12, 18, 24 and 30 days on the efficiency of digester operation. Percent methane in the biogas and methane production were dependent on both carbon-to-nitrogen ratio and hydraulic retention times. Percent chemical oxygen demand reduction, volatile solids removal, total volatile acids concentrations, digester pH and amount of sodium hydroxide solution needed to control digester pH were dependent on hydraulic retention time only.

HYDRAULIC PROPERTIES OF SOILS AS AFFECTED BY SURFACE APPLICATION OF WASTEWATER.

ABSTRACT WASTEWATER was applied to three soils to deter-mine the sealing affect or change in hydraulic properties. Saturated conductivities of disturbed soils were measured weekly under laboratory conditions over a 40-wk period. For the Lester clay loam and Waukegan silt loam, saturated conductivities of the soils were less than the saturated conductivities of the wastewater seal. In Hubbard loamy sand, an immediate seal was formed due to the application of wastewater.