The object of this study is to investigate the relationship between the air dilution sensory test and the threshold odor number (TON) method for evaluating the odor of domestic wastewater, plating plant wastewater, food plant wastewater and lake water. The dilution factor of raw wastewater evaluated by the air dilution sensory test was in the order of food plant > plating plant > domestic > lake, and that evaluated by the threshold odor number method was in the order of food plant > domestic > plating plant > lake. The same results were obtained when the raw wastewater and lake water were diluted 2 and 5 times with pure water. The relative geometric standard deviation determined from the threshold values of each panel on the air dilution sensory test was much larger than that calculated from results derived from the threshold odor number method. The relative geometric standard deviation obtained from samples with a low dilution factor was greater. There was a very good linear correlation (correlation coefficient = 0.968~1.000) between the air dilution sensory test and the threshold odor number method. But, the reduction in odor intensity (the slopes of regression curves) by dilution was dependent on the types of the odor-emission sources.

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.