Two sewage treatment facilities were selected to identify odor emission characteristics, focusing on volatile organic compounds (VOCs) and sulfur compounds. The complex odor, 5 kinds of sulfur compounds and 23 kinds of VOCs were analyzed from gas and sludge storages. Hydrogen sulfide was detected in the highest concentration and had the highest odor quotient among the odorous compounds monitored in this study, demonstrating that the contribution of hydrogen sulfide to the complex odor reached up to 90%. For VOCs, the overall contribution to the complex odor was not critical but VOCs can sufficiently trigger an odorous sensation because the sum of the odor quotient reached up to 2.89.

The odorants from wastewater sludge treated with four different chemical oxidants, i. e., potassium ferrate, sodium hypochlorite, sodium permanganate, and calcium nitrate, were analyzed. The release of odorants from the treated sludge was not completely eliminated, only retarded, possibly due to the low one time doseof oxidants. In a comparison of the concentration profiles of methyl mercaptan and dimethyl sulfide, calcium nitrate was the best of the four different oxidants at reducing their emission. For methyl mercaptan, calcium nitrate gave the best result, while for dimethyl sulfide, potassium permanganate was found to be the best oxidant. From this study, it was found that the oxidation-reduction potential (ORP) would be an easy and inexpensive parameter for the monitoring of the release of offensive odors.