Source Apportionment of Odour Impacts from Queensland Alumina Limited, Gladstone
Direct measurement of refinery odour sources, combined with hedonic tone analysis and odour dispersion modelling can assist in accurately identifing which odours cause the greatest impact on the community. Furthermore, this data can be used to assess the potential effectiveness of odour emission reduction projects.
There is increasing community concern over odour emissions, not just for alumina refineries but for all odour emitting sources. QAL has eliminated one major source of odour, and is continuing to proactively identify remaining sources that are having an impact on the community.
A survey of the plant was conducted using olfactometry to calculate a site specific odour emission rate for each source. The odour samples were also tested using a simplified version of the VDI 3882:2 standard for hedonic tone. Hedonic tone establishes the probable level of odour annoyance for each source at various concentrations at and above threshold. Source characteristics, along with comprehensive meteorological data were input to a CALPUFF model to predict the impact of these emissions likely to be experienced by the community.
Using combined methods of olfactometry, hedonic tone and modelling QAL was able to identify those sources most likely to impact on the local community. It was found that those odours with the highest emission rate may not be causing the greatest impact. Odour impact is also determined by the source characteristics (eg release height) or hedonic tone.
Engineering projects will be undertaken to determine the most feasible control or treatment strategy for emissions from the identified sources.