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ADVANCES IN ASSESSMENT OF ODOURS FROM ALUMINA REFINING

Forster, P.G., Woodford, N. and Schulz, T.

Odour emissions from alumina refineries can impact upon employees and neighbouring communities, with the significance of the impact dependent on the source of the odour, the point of discharge and the prevailing meteorological conditions. Of considerable importance to communities and employees that experience refinery odour emissions is an understanding of the substances that give rise to the characteristic refinery odour. However, measurement of chemical substances in ambient air often fails to detect substances that could be attributed to the prevailing odour.

A hybrid instrumental technique involving gas chromatography, mass spectrometry (GC/MS) coupled to an odour detection port has been used to study odours from alumina refineries. The volatile substances in the odours were separated by the GC and the effluent simultaneously directed to the MS analyser for identification and to the odour detection port for assessment by human nose. The intensity and character of the odours recorded by the assessor were correlated with the chemical speciation data to identify those substances that give rise to the majority of the odour. Odour thresholds have been determined for those substances to confirm the magnitude of their contribution to the total odour of the sample.

Results are presented that suggest a relatively small proportion of the volatile substances give rise to the odour from sources including digestion heater non-condensable emissions and calciner stack emissions.