Integration of Odour Emission Measurements from Area Sources with Dispersion Modelling Analysis of Environmental Impacts
This report was produced for the Urban Water Research Association of Australia, a now discontinued research program.
Report no. UWRAA 136
The report reviews literature on the development of sampling techniques for area sources. Particular focus was put on the direct sampling using the static USEPA isolation chamber and the dynamic UNSW wind tunnel systems.
An investigation was undertaken to establish the most likely ambient wind velocity passing across water surfaces of typical wastewater treatment plants at times of highest recorded levels of odour complaint. The investigation was based on an analysis of odour complaint data for two large wastewater treatment plants. The findings were then used to select an appropriate air velocity for use in the wind tunnel when used for odour sampling.
A laboratory investigation, based on three model compounds, to compare results obtained using a wind tunnel system with those obtained using an isolation chamber system. The model compounds selected were Acetone in aqueous solution(used to study gas phase controlled volatilization processes), Toluene in aqueous solution (used to study liquid phase volatilization processes) and Methyl ethyl ketone in aqueous solution (used to study both gas and liquid phase controlled volatilization processes).
Afield investigation was carried out at two typical wastewater treatment plants to compare specific odour emission rates determined on the basis of olfactometry samples obtained using a wind tunnel system with specific odour emission rates determined on the basis of olfactometry samples obtained using an isolation chamber system.
In order to model community odour impact, an investigation was undertaken at one of the wastewater treatment plants using the Ausplume dispersion model and specific odour emission rates determined on the basis of olfactometry samples obtained using a wind tunnel system. In addition the Ausplume model results were interpreted in relation to complaints data available for the plant.
The study concluded that the procedure developed could be used to predict the environmental impact for proposed facilities, for augmentation of existing facilities, and for assessing the odour impact implications of encroachment of residential/commercial developments into “buffer zone” area reservations around existing or proposed facilities. The study also concluded that the wind tunnel based procedures are reproducible, and can be applied to define performance targets for other, similar, wastewater treatment plant sites. Refinements are proposed to improve the accuracy of the procedures, and to enable approximately equivalent performance targets to be defined for emissions from sites incorporating sources with a range of dispersion characteristics.
The basic recommendation of the authors is that the use of the static isolation chamber be discontinued and that the use of portable wind tunnel systems be adopted provisionally for odour (and VOC) emission measurement sampling at wastewater treatment plants.