Development of odour impact criteria for sewage treatment plants using odour complaint history

Odour impact from a sewage treatment plant has been predicted using a Gausi an plume atmospheric model (Ausplume). A wind tunnel system was used to det ermine the odour emission from processing units. An improved technique for odour emission rate modelling is proposed to take account of wind speeds an d atmospheric stability classes. A new technique is proposed to define odou r impact criteria for sewage treatment plants. The dispersion model was cal ibrated using two years of odour complaint data. An odour concentration of 23 OU/m(3) as a one hour averaged 99.5th percentile was found to be appropr iate to minimise adverse community impacts, assuming lognormal human nose r esponse to odours and a "zero complaints" community objective. The proposed method can also be used to develop odour impact criteria for other industr ies.