COD modelling in sewer networks

In the context of the threat to the environment represented by the pollution of storm water, modelling is one way to study, characterize, understand and finally anticipate this pollution. This paper presents the modelling of the pollutants which are strongly attached to the suspended solids trough a potency factor governing the relation between these pollutants and TSS, developed for the COD. The constant potency factor throughout a subevent used in Flupol and Hydroworks DM is verified through an enlargement of the pollution database and a new variable formulation is presented. Simultaneous measurements of rainfall, hydraulic, TSS and COD concentration on three catchments which presented different characteristics and not used in the calibration phase allowed a large range of validation. This model provides a satisfying fitting of the real COD pollutographs and this, considering the general shape, overall and peak values, the variation of the potency factor (COD/TSS) through the rainfall and the simulation at the beginning of the rainfall.