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Comprehensive Odor Assessment at ABTP

The Problem
Residents near the City of Toronto’s largest wastewater treatment plant have complained over a number of years about nuisance odours. The City committed to address these odour concerns as part of a mediated agreement with community groups. The City contracted ZORIX to conduct a comprehensive odour assessment including development of recommendations to mitigate the off-property odour impact.

Our Approach
We designed and conducted a detailed assessment program based on sensory (odour panel) evaluations of samples collected from all significant odour sources at the plant. In order to develop a full understanding of seasonal variations odour sampling and impact analyses were performed during each of the four natural seasons. Chemical analyses were also performed at a number of representative sources to complete the picture. Dispersion modeling techniques were used to estimate potential worst-case odour impacts in the community. We also conducted ambient odour surveys in the affected community, using our trained odour surveyors, in order to verify modeled results.

The Solution
A comprehensive odour control strategy was developed based on our findings and the results of the assessment program. This strategy recommended process improvements to minimize and prevent the release of foul odours in addition to installation of new odour containment, capture and control systems. Biofiltration was recommended as the primary odour abatement technology for this application. Throughout the entire assessment program and development of recommendations ZORIX met regularly with members of community groups in order to explain the progress of work and to seek feedback as the program unfolded.

The odour control strategy and its recommendations were accepted by our client, and by the community representatives. An implementation plan is currently being developed by the City of Toronto.