Compost Pile Monitoring Using Different Approaches:GC-MS, E-nose and dynamic olfactometry

The evaluation of odour emissions associated to the composting process is complex because these emissions depend on several factors such as the raw material to be composted, the different stages of the composting process, meteorological conditions, and others.
For this reason, the aim of this paper is to compare complementary approaches to monitor odours. The odour source selected for this study is green waste compost at different maturity stages. The study site is a composting facility located in the south of Belgium. The compared
approaches were: a portable e-nose developed by the Environmental Monitoring Research team (Arlon, Belgium) to monitor odorous emissions from the composting piles; chemical analyses performed in the laboratory using a GC–MS (manufactured by Thermo) to analyse volatile organic compounds which were collected by active sampling on Tenax TA sorbent simultaneously to the in situ e-nose measurements and olfactometric measurements to
determine the odour concentration (ouE/m3) using the Odile olfactometer (Odotech). The portable e-nose was also used in the laboratory with compost odour samples collected in bags. The large numbers of data sets obtained were explored by statistical methods such as principal
components analysis. The results obtained highlight the advantages of monitoring the composting process with these three approaches. Each approach gives different
information about the composting process and the emissions generated. While the e-nose is capable of identifying some chemical family emissions and some activities such as turning steps, the GC–MS identifies each chemical compound emitted and dynamic olfactometry quantifies the odour concentration (ouE/m3) in relationship with these emissions.