How do we currently model micropollutants fate through WWTPs?
Modélisation des micropolluants en STEP: état de l'art
Résumé
Because of the evolution of the regulation and of the improvements in analysis technique, many models have been published in the last years to predict the fate of MP through bioreactors. The review proposed here concerns models published in scientific literature. Moreover we talk only about ASM-type models which are able to accurately describe removal mecanisms which are sorption and biodegaradation. Models published concern volatile organic carbons (VOCs), surfactants, and metals (particularly priority metals Cd, Pb, and Ni) with more than three different models for each. Moreover, PAHs (regulated in the WFD), bisphenol A , some pesticides (like DDT, dieldrin, lindane) are referenced in 2 or 3 models. In recent works, a few papers dealt with emerging as hormones and pharmaceutical substances. Other substances of interest, like regulated ones (Hg, nonylphenol for example) have never been considered. Current models adapted to micropollutants are able to give information about the processes involved and to help in the validation of utilized concepts. The fate of micropollutants can be identified: (i) remaining in the treated wastewater, (ii) sorbed on biological sludge, (iii) volatilized (for volatile compounds), (iv) biotransformed, or (v) photolysis (in lagoons). But models are not sufficiently advanced to be utilized for dimensioning treatment processes because of a lack of knowledge on mechanisms and the influence of local and operating conditions. Indeed, only a few papers have defined the conditions for which the model has been set-up, for instance temperature, mixed liquor suspended solids. Moreover, the production of metabolites is rarely considered in the equations.