Variations of odorous VOCs detected by different assessors via gas chromatography coupled with mass spectrometry and olfactory detection port (ODP) system

Odorous volatile organic compounds (VOCs) were analysed via a thermal desorption gas chromatograph coupled with a mass spectrometer and olfactory detection port (TD-GC-MS/ODP) to characterize odour emissions from a wastewater treatment plant (WWTP). Three trained ODP assessors, screened according to the European dynamic olfactometry standard (EN: 13725), were used for the olfactory analysis. Their sensitivity to n-butanol varied within the acceptable limits. VOC samples from the WWTP were collected onto Tenax TA sorbent tubes in triplicate and each assessor analysed one tube in the same sample desorbing and analysing conditions. Intensities of odours detected from ODP were scaled from 1 to 4. The ODP assessors used their own odour descriptors based on their own experience as well as referenced descriptors on published compost and wastewater odour wheels. The ODP assessors detected a total of 32 different odorous VOCs; however, the intensities assigned by each assessor to particular VOCs varied. Moreover, some odorous VOCs were not detected by all assessors. For example, geosmin was detected by only two assessors. The use of a TD-GC-MS/ODP system for the analysis of odorous VOCs is valuable when analysed by different assessors, allowing a range of responses to specific odorants in a populations to be investigated.