An odor is referred to or described as an unpleasant smell that creates a disagreeable atmosphere and may impinge on the quality of life of people. Most of the odors that stimulate the human sense of smell and engender feelings of discomfort and disgust are odors mixed with various chemicals substances. Among designated odor substances, acetaldehyde, propionaldehyde, butyraldehyde, n-valeraldehyde, and iso-valeraldehyde may cause an irritating and sour sensation and give rise to headache, dizziness, vomiting, and unconsciousness. These aldehyde substances are mainly discharged in high concentrations from food chemicals, petrochemicals, and printing industry sources. The odor control technologies applied to prevent odors from aldehydes are absorption, adsorption, as well as biological methods and combustion methods. The threshold concentrations of aldehydes are low so that odors can be easily experienced even at very low concentrations. It is not easy to control aldehydes due to their particular physicochemical properties and because aging and poor management of the odor prevention technology is usually only available. In this study, trends with regard to research efforts on the development of technology that is effective in treating aldehydes were summarized.

Environmental fundamental facilities have different odor emission characteristics depending on the type of treatment facilities. To overcome the limitations of the olfactometry method, research needs to be conducted on how to calculate the dilution factor from the individual odor concentrations. The aim of this study was to determine the air dilution factor estimated from manually measured concentration data of individual odor substances (22 specified odor species) in three environmental treatment facilities. In order to calculate the optimum algorism for each environmental fundamental facility, three types of facilities were selected, the concentration of odor substances in the exhaust gas was measured, and the contribution of the overall dilution factor was evaluated. To estimate the dilution factor, four to six algorism were induced and evaluated by correlation analysis between substance concentration and complex odor data. Dilution factors from O municipal water treatment (MWT) and Y livestock wastewater treatment (LWT) facilities showed high level of dilution factors, because concentration levels of hydrogen sulfide and methylmercaptan, which had low odor threshold concentrations, were high. In S food waste treatment (FWT) facility, the aldehyde group strongly influenced dilution the factor (dominant substance: acetaldehyde, i-valeraldhyde and methylmercaptan). In the evaluation of four to six algorism to estimate the dilution factor, the vector algorism (described in the text) was optimum for O MWT and Y LWT, while the algorism using the sum of the top-three dominant substances showed the best outcome for S FWT. In further studies, estimation of the dilution factor from simultaneously monitored data by odor sensors will be developed and integrated with the results in this study.

The correlations among odor intensity, offensive substance concentration, and dilution factor were reviewed for the 12 designated offensive odor substances in this study. It is to propose new regulatory odor standards based on relationships between odor intensity and offensive substance concentration, as well as odor intensity and dilution factor at the site boundary which were obtained from the comprehensive reviews of the adequacy of current regulation standards. Changes in intensity were found to be necessary to reflect exponential changes in concentrations and dilution factors. The change of substance concentrations with respect to the dilution factor was found to be a relatively linear relationship. The thorough evaluations pf relationships among odor intensity, offensive substance concentration, and dilution factor led to the conclusion that the current regulatory standards were inadequate and the modification was necessary to reflect the new understandings. The new regulatory substance standards based on correlations with odor intensity for the 12 compounds were proposed. The proposed ammonia concentrations for the regulatory standard in the semi-industrial and industrial area were 15 ppm and 28 ppm, respectively. These are approximately 15 times higher than those of the current standards. For dimethyl sulfide, dimethyl disulfide, and isovaleraldehyde, the higher concentrations than those of current standards were also pro posed. The proposed regulatory standards of dilution factor in semi-industrial and industrial area were 25 and 50, respectively. It is found that proposed quantitative relationships among the odor intensity, the offensive substance concentration, and the dilution factor in this study turned out to be more adequate to Korean than the current ones.

This research determined the threshold value of 12 specified offensive odor substances based on the 3 point comparison sensory method. The panelist’s thresholds were calculated by taking the arithmetic, geometric mean, and 50th percentile. Three methods of calculating the odor thresholds from the same data are compared. For 12 odor substances, the panelist’s thresholds were showed logarithmically normal distribution. The 50th percentile was the best method among the three methods of caculating the odor threshold from the 72 panel’s thresholdes. As a result, the threshold values of individual odor substances, including methyl mercaptane, hydrogen sulfide, trimethylamine, and i-valeraldehyde ranged between 0.0001~0.001 ppm, while the values of styrene and ammonia were relatively higher than of other substances at 0.089 ppm and 3.2 ppm, respectively. The threshold values of the 12 specified odor substances were compared in Korea and overseas, which showed that the characteristics of sensory response varied by substance and nation.

This study aims to produce the threshold values of 12 specified offensive odor substances based on the 3 point comparison method instead of the 2 point comparison method of ASTM or CEN. As a result, the threshold values of individual odor substances, including Methyl mercaptane, Hydrogen sulfide, Trimethylamine, and I-Valeraldehyde ranged between 0.0001∼0.001ppm, while the values of Styrene and Ammonia were relatively higher than of other substances at 1.8ppm and 0.04 ppm respectively. The threshold values of the 12 specified odor substances were compared in Korea and overseas, which showed that the characteristics of olfactory response varied by substance and nation. When it comes to acetaldehyde or hydrogen sulfide, western countries, including the United States, tended to quite insensible compared to Koreans. Japanese people were more sensitive in the 12 specified odor substances than Koreans in general, suggesting that it is not only because of its olfactory ability, but because of the calculation method that produces Japan‘s dilution threshold values approximately 1.5 times as high as Korea"s.

This study was carried out to investigate the characteristics of major odorous pollutants emitted from foodwaste treatment facilities for providing the basic information in field of prevention. Twelve odorous components were analyzed at unit processes in 3 plants on May, August and October. The major odorous components appeared to be Ammonia (559.42 ppb), Acetaldehyde (229.70 ppb), Methylmercaptan (50.39 ppb) and Hydrogen sulfide (48.90 ppb). In the view-point of COC (Calculated Odor Concentration) based on odor threshold, A plant showed the highest value. The major odor active facilities were prevention ＞ input ＞ afterripening ＞ fermentation ＞ boundary ＞ pretreatment. The major odor active components were Hydrogen sulfide, Methylmercaptan, Acetaldehyde and i-valeraldehyde. It is important that the findings on major odor active facilities and components should be referred in the design of odor treatment process to the specific plants.

In this study, we attempt to analyze for 4 compounds (MEK, MIBK, n-Butyl acetate, i-Butyl alcohol) in ambient air using on-line thermal desorber (on-line TD) with gas chromatograph/flame ionization detector (GC/FID). These compounds will be regulated by KMOE (Korean ministry of environment) within 2010. We tested two different experimentation. First, we try to find the influence of Nafion dryer for the 4 compounds. Second, we want to know basic analytical characteristic of target compounds through the linearity, reproducibility, and minimum detection limit. According to this study, target compounds are removed in Nafion dryer more than 80 percent, respectively. So, we progressed next experimentation progressed without Nafion dryer using hydrophobic cold trap. Results for each compounds showed good linearity (r²＝0.99 upper) and good precision (RSD＝1 % below). In additional, we analyzed the ozone precusors standard gas (56 compounds) using the same method to see if there are any peaks to be overlapped in ambient air. These results showed that there is no peak overlapped. This means that analytical system of this study could be used on-line analytical system. Minimum detection limit (MDL) value for this system are less than minimum malodor threshold concentration.

The aim of this study was to investigate the legally-designated malodorous compounds at the plant boundary areas of 5 plants expected to emit high odor intensities, as well as! complaint area at the Yeosu petrochemical industrial complex in Korea. The sampling was carried out during spring and summer of 2003 and 2006. The concentrations of ammonia, sulfur compounds (hydrogen sulfide, methyl mercaptan, and dimethyl sulfide) and aldehydes (acetaldehyde and propionaldehyde) emitted during 2006 were higher than those emitted during 2003, and the concentrations emitted during summer were higher than those emitted during spring at the plant boundary areas. It was thought that the concentrations of odorants in the complaint area had been directly influenced by the concentrations of odorants in the plant boundary areas as they showed similar patterns of concentration variations. While the concentration of TMA during 2006 was lower than during 2003 at the all sampling sites, the concentration of styrene during 2006 was higher than during 2003 at the all sampling sites. The sites showed high concentrationsof odorous compounds at the plant boundary area of the related chemical and petrochemical refinery plants.

This study was performed to obtain the emission characteristics of odor compounds generated from a livestock wastewater treatment process. The sampling of odor compounds was performed twice, on May 9th and June 14th 2006, at 4 and 5 sites in the boundary and source areas, respectively. The odor concentrations obtained from the air dilution sensory test ranged from 10 to 100 in the boundary area. Of the 5 source sites, the odor concentrations found at the pre-treatment building had the highest values, which were 14422 and 20800 for the first and second dates, respectively. To estimate the major odor compounds produced during a live wastewater process, the contributions of 12 odor compounds to the total odor were calculated from the concentration and odor threshold values of each compound. At the pre-treatment building and outlet of the activated carbon tower of the source sites, the contribution of sulfur compounds to the odor was 97%, and at the outlet of the biofilter that of NH₃ was 90%. The order of the contribution to the odor in the boundary area sites was; from highest to lowest: H₂S, C₂H₆S, i-C₅H10O, C₃H₉N, NH₃. The correlation coefficient between the theoretical odor concentration from the odor threshold of 12 odor compounds and that obtained from the air dilution sensory test was 0.73. This result indicated a limit to the correct analysis of the odor concentration obtained from the air dilution sensory test when only 12 odorous compounds at a livestock wastewater treatment process are used. The odor removal efficiency of the deodorization facilities showed that for the activation carbon tower, the odor concentration was reduced to 4% and the contributions of H₂S, C₂H₆S and NH₃, which were estimated to be the major odor compounds, were reduced to 20, 26 and 11%, respectively. With respect to the bio-filter, the removal efficiency of the odor compounds revealed an odor concentration of 0% because the major odor compounds were calculated as negative percentages.