Case Study: Odour Risk Management at the WTP, one of Australia's Largest and Most Unique WWTPS
The Western Treatment Plant (WTP) is one of Australia’s largest and most unique wastewater treatment plants treating over 52% of Melbourne’s sewage. Although there is an existing Environmental Improvement Program already in place which has contributed to an estimated odour reduction by 90% at the WTP site, the purpose of the odour reduction project was to identify any further odour mitigation approaches which could be implemented. Changes in odour emissions from any of the various sources can have a significant effect on off site odours. Reliably assessing the varying impact of these sources is a complex task due to the scale and the unique nature of the facility. Accurate assessment of impacts is critical to enable cost effective and viable odour mitigation options to be implemented.
The data collection and assessment phase of the project made use of a unique combination of tools including field olfactometry, dispersion modelling of major source emissions, and various community odour surveys. By collecting a wide range of data it was possible to cost effectively establish seasonal and diurnal odour variation and to validate assumptions and emission data used, so that more accurate dispersion modelling and impact assessments could be undertaken. The investigation also provided an assessment of the available odour dispersion models, (Ausplume, CALPUFF and TAPM) and their appropriateness for assessing odour impacts at this site.
This paper presents the results of this investigation including some interesting findings about the relationships between odour strength, human perception and odour annoyance in the community.