M8 AM Persistent Organic Pollutants
Monday, 14 November 2005: 8:00 AM - 11:40 AM in 337-338

(SET-1117-822824) STP Model: Calibration and testing on a full-scale sewage treatment plant.

Seth, R¹, Wang, J¹, Drouillard, K¹, ¹ University of Windsor, Windsor, Ontario, Canada

ABSTRACT- Sewage treatment plants (STPs) can be a significant source of exposure to humans and the environment for a variety of chemicals of historical and emerging concern. Most countries require that such chemicals and especially those which are new to commerce be assessed for their treatability in sewage treatment plants using a screening level model. The STP model has been used widely for such assessments in Canada, the U.S. and elsewhere. For chemicals with biodegradation as a significant loss process, the greatest uncertainty in model predictions is in its loss by the process. This is mainly due to the uncertainty surrounding the proper selection or derivation of biodegradation rate constants for application to the various stages of the sewage treatment process. Samples were collected under dry-weather conditions at six different locations at the Little River STP in Windsor, Ontario, Canada in this study, and analyzed for a suite of 31 chemicals of historical concern, including PAHs, chlorobenzenes, and organochlorine pesticides. A dataset comprising of ten PAHs, which were detected at all stages of the treatment process, was compiled and used for the calibration and testing of the STP model. The results suggest that the biodegradation rate constant for use in the STP model could be derived from those reported in surface waters, by applying a factor. A range for such a factor is suggested. The results using the factor show excellent agreement between the observed and modeled chemical trends during the treatment process for all the ten PAHs.

Key words: STP model, sewage treatment, fate and transport, polynuclear aromatic hydrocarbons