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Odors due to malodorous gas and vapor emissions from units of Izmir Wastewater Treatment Plant (WWTP) were studied and evaluated with respect to chemical composition. Altogether 29 target compounds consisting of 4 different groups of chemicals were identified and quantified in the odorous gas samples from wastewater and sludges. Total volatile malodorous organic compounds (VMOC) consisted of reduced sulfur compounds (RSCs) and different volatile organic compounds (VOCs) including volatile organic compounds (VOCs), aldehydes, monoaromatics (BTX) and some halogenated organics. Among these components the most abundant group was the monoaromatics (69% of the total VOC). A statistically significant linear relationship was found between odor concentrations determined by olfactometry and total VOC concentrations (r(2)=0.89, n=5, P<0.05) in the samples of odorous gases. Based on the odor contribution ratios of the compounds studied, the results of the study revealed that hydrogen sulfide, propanal and toluene were dominating in the odor emissions and these were explaining 99% of the variability in odor concentrations (r(2)=0.99, n=5, P<0.05). It was shown that not only the hydrogen sulfide and RSCs but also other organics were important in forming the odors from sludge units and sludge management areas.

Abstract: The composition of odorous gases emitted from a municipal landfill in the city of Izmir, Turkey was investigated using gas chromatography–mass spectrometry, and these data were examined in relation with the odor concentrations. Several volatile organic compounds (VOCs) were identified and quantified at five sampling sites in May and September 2005. Detected VOCs were monoaromatics (0.09–47.42μgm−3), halogenated compounds (0.001–62.91μgm−3), aldehydes (0.01–38.55μgm−3), esters (0.01–7.54μgm−3), ketones (0.03–67.60μgm−3), sulfur/nitrogen containing compounds (0.03–5.05μgm−3), and volatile fatty acids (VFAs) (0.05–43.71μgm−3). High levels of aldehydes (propanal up to 38.55μgm−3) and VFAs (formic acid up to 43.71μgm−3) were measured in May. However, VOC concentrations were relatively low in September. The monoaromatics and halogenated compounds were the abundant VOCs in landfill air for the both sampling periods. The benzene-to-toluene (B:T) ratio at the landfill site was significantly lower than urban areas indicating the presence of higher amounts of toluene in landfills compared to traffic exhaust rich urban areas. A statistically significant linear relationship was found between odor concentrations determined by olfactometry and total VOC concentrations. The relationships of odor concentrations with the different groups of chemicals were also examined using a step-wise multiple regression analysis. It was found that the concentrations of aldehydes, ketones, and esters are the best estimators, explaining 96% of the variability in odor concentrations (r 2 =0.96, n =10, P < 0.01). [Copyright &y& Elsevier]