Odour measurements for sewage treatment works

Public concern over odours from sewage treatment works is increasing. More people are being exposed to odours, due to development around existing work s or construction of new works. Increased awareness of both the environment and individual rights has meant people are now more likely to complain. Od our abatement and control is a major issue for sewage works operators. To c ontrol odours, they must first be measured. This is no easy task as respons e to odours is subjective. Our understanding of the sense of smell is incom plete, and there is no single measure that will directly relate to the like lihood of complaint. Odour measurement has often been regarded as an art as opposed to a science. Odour measurement techniques fail into two classes. Sensory measurements employ the human nose and measure the effects of the o dour as perceived by an observer. Analytical measurements characterise odou rs in terms of their chemical composition and attempt to quantify the odora nts present. Both methods are less than ideal - sensory measurements can be overly subjective and the interpretation of results requires care. Analyti cal measurements are complicated by the large number of odorants present, o ften at concentrations close to detection limits. Our incomplete understand ing of odour perception makes linking analytical and sensory measurements d ifficult. This paper reviews the methods applied to sewage treatment works odour measurement. Sensory and analytical measurements are reviewed, along with a recent development, the electronic nose. (C) 2001 Elsevier Science L td. All rights reserved.