Daily changes in the river water quality due to the effect of a treated discharge

At present, the river water quality protection has to be planned so as not to exceed the pollutanttolerance threshold, in other word the environmental receptivity. The environmental receptivity evaluation is very complex since require the knowledge of the transport and biodegradation processes in the river. Particularly, in river with stream regime, typical of the Mediterranean area, the environmental receptivity evaluation presents additional difficulties due to the hydraulic regime that does not allows constant dilution and self-cleaning capacities.