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Field Measurement of Ambient Odors with a Butanol Olfactometer

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... Odor Intensity , matching butanol concentration. 1.25-80 ppm range, T AMU Butanol Olfactometer Sweeten et al. , 1983). ...
... A single observer was used with the Scentometer throughout the experiment. Field procedures for use of the portable TAMU Butanol Olfactometer (which produces a stream of butanol of 1.25 to 80 ppm from liquid butanol using an icebath condenser and dilution breathing air and preset air valves) were described by Sweeten et al. (1983), and data handling procedures were described previously . The method of determining the panel composite average for each test was illustrated in Sweeten et al. (1988). ...
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High intensity odors from a poultry manure composting building were controlled by discharging them with a fan-blower through perforated pipe beneath 20-25 cm (8-10 in.) of sand and pea gravel in a 0.23 ha (0.57 ac) soil filter field. Ammonia concentrations were reduced by 97-99%. Odor intensity measured with a butanol olfactometer decreased by 30-80% as compared to composting building odors.
... When tests are duplicated in the same laboratory and compared to other analytical techniques, the human panelists will vary only 12-17% ( Clanton et al., 1999). One of the problems with this method, according to Sweeten et al. (1983), is that the odor detection threshold is not a consistent number but will vary, within a specific range or zone, with each individual panel. Also, the DT of an air sample cannot be directly correlated to the intensity of an odor. ...
... Also, the DT of an air sample cannot be directly correlated to the intensity of an odor. The intensity of the odor must be determined indirectly by comparing the odorous air sample to known concentrations of n-butanol (C4H9OH) in water ( Sweeten et al., 1983). Several standard concentrations are formulated and used to compare with an odor sample. ...
Conference Paper
Odor samples were collected two to four times per month over a one-year period in 2002-2003 at three large open-lot beef cattle feedyards in the Texas panhandle. Samples were collected in 10 L Tedlar bags using a vacuum chamber upwind of the feedyard, downwind of the pens, and downwind of the runoff storage pond. Samples were analyzed in the odor lab for detection threshold (DT) using triangular forced choice olfactometry with trained human odor panelists. Full-strength odor samples were also analyzed for intensity and hedonic tone. Weather data was collected on-site at each of the feedyards for correlation to odor characteristics. At two of the feedyards, mean upwind DTs were similar to DTs downwind of the pens and storage pond, ranging from 33 to 45. At the third feedyard, the mean upwind DT was 36, compared to 68 downwind of the pens and 124 downwind of the pond. Results of the research indicate that DT alone may not be a good indicator of odor characteristics and offensiveness from beef cattle feedyards.
... When tests are duplicated in the same laboratory and compared to other analytical techniques, the human panelists will vary only 12-17% (Clanton et al., 1999). One of the problems with this method, according to Sweeten et al. (1983), is that the odor detection threshold is not a consistent number but will vary, within a specific range or zone, with each individual panel. Also, the DT of an air sample cannot be directly correlated to the intensity of an odor. ...
... Also, the DT of an air sample cannot be directly correlated to the intensity of an odor. The intensity of the odor must be determined indirectly by comparing the odorous air sample to known concentrations of n-butanol (C 4 H 9 OH) in water (Sweeten et al., 1983). Several standard concentrations are formulated and used to compare with an odor sample. ...
Conference Paper
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Amendments for reducing odor from open-lot beef cattle feedyards were evaluated in the laboratory. Manure was placed in small Tupperware® containers. Water and amendments were added to the manure surface and the containers were attached to a vacuum pump that continually passed 2.5 L/min of carbon-filtered air over the surface. Eleven different amendments were tested, at two different concentrations, in a series of five experiments. Odor samples were collected 3 times during a 10-day period in each experiment and were analyzed by trained panelists for detection threshold (DT), intensity and hedonic tone. None of the amendments showed any overwhelming evidence of greatly reducing odor from simulated open-lot feedyard surfaces.
... Clanton et al. (1999) stated that the use of human panelists surpasses the combination of high-resolution gas chromatography and mass spectrometry when quantifying and identifying odorous compounds in small amounts. One of the difficulties with olfactometry is that odor DT is not a consistent number, but may vary with each panel (Sweeten et al., 1983), although this can be said of virtually every odor measurement method. Triangular forced-choice olfactometry continues to be one of the primary methods of odor assessment for swine (Bicudo et al., 2004;Gay et al., 2003;Galvin et al., 2003;Lim et al., 2001;Zhu et al., 1999) and dairy (Gay et al., 2003;Zhu et al., 1999) M facilities. ...
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Odor is a growing concern at concentrated animal feeding operations as residential houses encroach upon rural areas once occupied only by agriculture. A research project was conducted to determine baseline ambient odor characteristics at large open-lot beef cattle feedyards and to develop a better understanding of when and why odors occur at feedyards. Ambient odor samples were collected two to four times per month over a 12-month period in 2002-2003 at three large commercial open-lot beef cattle feedyards in the Texas panhandle. Ambient odor samples were collected upwind of the feedyard, downwind of the pens, and downwind of the runoff storage pond. Odor samples were also collected on five separate days covering four months in 2004 from a surface isolation flux chamber to estimate odor emission rates from the feedyard surface. All odor samples were collected in 10 L Tedlar bags and analyzed with trained human odor panelists for odor concentration (detection threshold, DT) by dynamic dilution forced-choice olfactometry, intensity by reference scaling, and hedonic tone. Manure moisture content and weather data were collected on-site at each of the feedyards. At two of the feedyards, mean DTs downwind of the pens and storage pond were statistically similar to upwind DTs, ranging from 33 to 45 OU m-3. At the third feedyard, mean DTs downwind of the pens (69 OU m-3) and pond (124 OU m-3) were statistically higher than the mean upwind DT (36 OU m-3) (p < 0.05). Odor emission rates ranged from 0.3 to 3.2 OU m-2 s-1 during a period when downwind DTs ranged from 17 to 132 OU m-3. A number of elevated DTs were explained by elevated manure moisture contents from recent precipitation. These results demonstrate that odor production from open-lot beef cattle feedyards is a complex phenomenon that depends at least partially on weather conditions. Thus, odor prediction and control will likely be difficult at these facilities.
... The use of human panelists has long been considered the standard for quantification of odors, as the human nose can often detect odors below the detection levels of current analytical equipment (Parker et al., 2007). One of the difficulties with olfactometry is the inherent variability between odor panelists (Sweeten et al., 1983; Clanton et al., 1999). Nevertheless, triangular forced‐choice olfactometry is a standard method for quantifying odors with human panelists (CEN, 1999; ASTM, 2001b) one of the primary methods of odor assessment for animal feeding operations (Zhu et al., 1999; Lim et al., 2001; Gay et al., 2003; Galvin et al., 2003; Bicudo et al., 2004). ...
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Odor is a concern at many large animal feeding operations. Due to complaints from downwind neighbors, a project was initiated to reduce emissions of odor and volatile organic compounds (VOCs) from a 3000-cow dairy. An initial odor evaluation showed that the volatile solids loading rate to the lagoons was 15 times that recommended by ASABE standards, and that the primary source of the odor problem was the two lagoons. Abatement measures included covering the treatment lagoon, adding additional aeration capacity to the storage lagoon, and reducing the volatile solids loading rate to both lagoons. Odor, hydrogen sulfide, and water quality were monitored initially and at the completion of the project. A laboratory-based wind tunnel and gas chromatographic method was developed to evaluate reduction in VOC emissions of phenol,4-ethylphenol, p-cresol, indole, skatole, and seven volatile fatty acids. Dramatic improvements in ambient air quality were observed after 30 months, with 80% reduction in ambient odor concentrations and 96% reduction in ambient H2S concentrations downwind of the lagoons. There was a 94.2% reduction in total odorous VOC emissions from the lagoons as measured under laboratory conditions with the small wind tunnel. Paralleled improvements in water quality were observed, with a 55.3% reduction in BOD5, 84.1% reduction in VFAs, and 76.3% increase in oxidation reduction potential (ORP). These results demonstrate the potential for air quality improvements with best management practices such as lagoon covers, aeration, and using innovative methods for reducing the volatile solids loading rate. Relative improvements are always site specific.
... Human sensory methods are the most commonly used. They involve collecting and presenting odor samples (diluted or undiluted) to panelists under controlled conditions using scentometers (Huey et al., 1960;Barneby-Cheny, 1987;Miner and Stroh, 1976: Sweeten et al. 1977, 1983, 1991, dynamic olfactometers, and absortion media (Miner and Licht, 1981;Williams and Schiffman, 1996;Schiffman and Williams, 1999). Among sensory methods the Dynamic Triangle Forced-Choice Olfactometer (Hobbs et al., 1999;Watts et al., 1994;Ogink et al.1997) appears to be the instrument of choice. ...
... After numerous preliminary field investigations, the butanol olfactometer was utilized for odor measurement in 49 field experiments involving five to seven panel members, most of whom had been trained during the laboratory experiments. Matching butanol concentrations for each panelist were determined using a procedure described by Sweeten et al. 8 These matching butanol concentrations were converted to olfactometer scale steps and averaged arith-metically^ to obtain the mean panel response, L, for each experiment. Observations reported as > 0 but < 1.25 pm were assigned L values of 0.5 and concentrations > 80 ppm were reported as L = 7.5. ...
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A portable 1-butanol olfactometer was developed for quantifying odors in ambient air. Panelists compare the intensity of ambient odors with the intensity of discrete levels of 1-butanol provided by the olfactometer. Range of delivered 1-butanol concentrations Is 0 to 80 ppm in air at a flow rate of 15 L/min. Laboratory tests were performed to ascertain overall precision, consistency of panelist responses, uniqueness of each odor step, variability between two Identical olfactometers, and effect of delivery method. For 855 pairs of matched odor Intensities, the ratio of measured butanol concentration to set concentration averaged 0.984 or —0.023 scale steps (where the scale steps differ In concentration by factors of two). In field experiments the equivalent ambient odor Intensities determined by odor panels using the butanol olfactometer ranged from 1.5 ppm to 64 ppm of 1-butanol vapor In air. The precision of ambient odor measurements was within one-half scale step on the 1-butanol olfactometer, sufficient for most odor investigation and abatement research applications.
... There are several sensory methods of measuring odor including static (syringe) dilution and forced choice triangle dynamic olfactometer (ASTM, 1975;ASTM, 1978;ASTM, 1979;Dravnieks and O'Neill, 1979;National Research Council, 1979). A portable butanol olfactometer was developed at Texas A&M University to enable panelists to measure odor in terms of equivalent parts per million of butanol Sweeten et al., 1983). The butanol olfactometer is useful and sufficiently accurate for ambient odor measurement at area sources including open cattle feedlots. ...
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One approach to odor abatement at swine facilities is to provide adequate buffer zone or separation distance from neighbors. Use of a nutrient (nitrogen and phosphorus) balance to determine land requirements appropriate for the facility size and type of manure management system will provide considerable separation distance. Procedures and examples for determining a phosphorus and nitrogen balance and resulting theoretical minimum separation distances were presented. Results of field odor concentration measurements at two swine operations of differing size and type were presented, along with the required distances to reach near-background odor levels.
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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. Keywords. Odor evaluation, Manure management, Ventilation system, Air flow rate, Air quality. dor nuisance continues to be a major issue for the swine industry, which is an important sector of the agricultural economy in the United States. Therefore, a significant amount of research has been initiated to better understand the nature and control of
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This paper treats the field measurement of odors and odorants in the context of environmental odor nuisance control. The work reported was carried out by Shell Development Company as a part of its environmental conservation research. This paper deals with the scientific and technical needs of the public and private sectors in the development of valid and reasonable odor control regulations. This paper describes the field application of an ASTM method for ″Referencing Suprathreshold Odors″ to environmental odor measurements.
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Certain odor control regulations specify use of the Scentometer for ambient odor measurement. This evaluation is usually performed by a single individual who is surrounded by the odorous environment to be measured. A method is desired where an ambient odor sample can be evaluated by an adequate size panel in an odor-free atmosphere. A dynamic forced-choice triangle olfactometer was designed and constructed to measure ambient odors. Teflon bags of 18 liter capacity collect a sample within 2-3 minutes which includes pre-flushing the bag. The sample is evaluated by a dynamic olfactometer equipped with 5 dilution levels (81×, 27×, 9×, 3× and undiluted sample). Three sniffing ports are provided at each dilution level to present dynamically one diluted odor stimulus and two odor-free air blanks. Each panelist is required to indicate which port contains the odor. Evaluation of one sample is routinely completed by a panel of 9 within less than 15 minutes. The odor threshold value (ED50) for the panel is calculated by use of a simple table derived statistically. No significant loss of odor was observed in sampling and in storage of rendering odors up to 48 hours. Bags were reusable after flushing with odor-free air. Reproducibility of log ED50 values by the same panel was within a σ = 0.10 log10. Agreement in evaluating duplicate field samples by two different panels was within the same limits. Under controlled laboratory conditions, a Scentometer reading of D/T = 2 was equivalent to an ED50 = 4.8; and D/T = 7 was equal to ED50 = 9.5.
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