This study investigated the retention characteristics of odorants in polyethylene terephthalate (PET) odor bags used in the triangular odor bag method, which is officially recognized as a standard procedure for odor threshold measurement. To specifically evaluate the adsorption behavior of the bag material under threshold testing conditions, single-compound odor samples were introduced into the bags, and the concentrations of the odorants upon release were measured using instrumental analysis. The recovery rate was defined as the ratio of the measured concentration to the estimated initial concentration. Five representative malodorous compounds were tested: hydrogen sulfide, toluene, isovaleric acid, acetaldehyde, and skatole. The average recovery rates were 39% for hydrogen sulfide, 77% for toluene, 12% for isovaleric acid, 91% for acetaldehyde, and 34% for skatole. The recovery rates varied by up to eightfold among the compounds, indicating large differences in retention behavior. These findings demonstrate significant variability in odorant recovery depending on the physicochemical properties of each compound, emphasizing the need to consider compound-specific recovery rates when using PET odor bags for reliable odor threshold measurements.

In this study, the ammonia and isovaleric acid removal performance of glass foaming materials was preliminarily investigated. The unprocessed glass foaming materials exhibited almost no ammonia removal performance, whereas a 12-s contact time resulted in 100% removal of isovaleric acid. When the glass foaming materials were immersed in distilled water or activated sludge, the ammonia removal performance improved in the following order: immersion in distilled water < immersion in activated sludge < long-term immersion in activated sludge. In contrast, the isovaleric acid removal performance improved compared with that of the unprocessed glass foaming materials, but no differences were observed among immersion in distilled water, immersion in activated sludge, and long-term immersion in activated sludge.