Evaluation of the chemical composition and correlation between the calculated and measured odour concentration of odorous gases from a landfill in Beijing, China

Abstract

Odorous gases emitted from landfills have always been a public concern, but studies evaluating the odour contribution and the correlation between the odour concentrations are limited. The objectives of this study were to assess the odour contribution and to correlate the measured odour concentration COD with the calculated odour concentration SOAV, which was calculated as sum of individual odour activity value (OAV). Odorous air samples from a landfill in Beijing were collected seasonally and measured by both gas chromatography and an olfactometer. Different from previous studies, we measured the odour threshold of 51 detected compounds using a uniform methodology to minimize the imprecision of citing odour threshold from disparate literature. The odour threshold is used to convert the individual chemical concentration into the OAV, which is used as a surrogate of the odour concentration. Evaluation of the OAV revealed that hydrogen sulfide (65.9%), dimethyl sulfide (14.4%) and trimethylamine (8.6%) contributed the most to the odour at the landfill. Moreover, the correlation between the calculated odour concentration SOAV and the measured odour concentration COD resulted in a linear regression equation of COD = 6.28 SOAV (r = 0.914, n = 24, p < 0.01). Based on the scaling factor K = 6.28, the average ratio of calculated odour concentration to measured odour concentration could be improved from less than 0.2 to 1.1. By the calibration of the calculated odour concentration SOAV, it is possible to use continuous measurements of chemical concentrations to derive odour concentration for this site for monitoring purposes.