Abstract
A gas chromatography - olfactometry analysis was conducted for biologically treated wastewater samples from seven different plants to clarify the compounds responsible for the odor of biologically treated wastewater. The odor of 2,4,6-trichloroanisole was detected with the highest or second-highest odor intensity for the treated wastewater samples from large-scale plants whose biological reactors are covered with a roof. The treated wastewater from these large-scale plants contained 11.6–21.2 ng L-1 of 2,4,6-trichloroanisole, and this range of concentration was approximately 100 times as high as the olfactory threshold. Earthy and musty odors, probably caused by geosmin and 2-methylisoborneol, were also detected with high odor intensities in all samples. A large contribution of an unidentified compound with a sweet odor was also observed in the analysis of treated water samples. In addition to earthy and musty odors, sulfuric and septic odors were detected in the samples from small-scale plants.
