PEGASE, AN INTEGRATED RIVER/BASIN MODEL DEDICATED TO SURFACE WATER QUALITY ASSESSMENT: APPLICATION TO COCAINE

The scientists of the Aquapole of the University of Liege have been involved in environmental modeling for more than 20 years. Among other, its current R&D unit focuses on the compartment of surface water, and - for modeling processes - is specialized on the water quality. One of its environmental models, called PEGASE (Planification Et Gestion de l'ASsainissement des Eaux), French acronym for "Planning and management of water purification" is devoted to the modeling of the environmental state of surface water, at different scales from small watersheds (10 km(2)) and basins up to entire transnational Districts (more than 100.000 km2). The software is used operationally by several administrations (Agencies and Ministries) mainly through Europe (France and Benelux, Germany ...), and several calculations have also been performed at international District levels for international commissions (Scheldt, Meuse, Moselle ...). Recently, the PEGASE model has been adapted to describe the cocaine's behavior (using a stable metabolite of the cocaine in the environment: the benzoylecgonine) in waste water, waste water treatment plants (WWTP) and surface water. The cocaine is newly described in the model as an additional micropollutant (Pegase already treats numerous heavy metals), thanks to the implementation of new state variable equations and their specific parameterizations. At a first stage, only the urban sources (releases associated to the consumption by inhabitants) were considered as the industrial releases and the soil loads are assumed to be negligible. Simulations of benzoylecgonine have been done in the Walloon and Flemish regions, where many measurements from the COWAT project were available. These first results are showing a good agreement between calculated and measured values. This ability of the model to simulate the fate of the cocaine derivatives in surface waters should be continued and extended to other metabolites.