Effet de traitement thermique sur le comportement physico-chimique et rhéologique des boues activées de station d'épuration

The water treatment, which it about production of drinking water where of waste water purification of urban or industrial origin, always leads to the sludge formation which one separates and of treated water. This sludge arises to the exit of the purification plant like a liquid with strong water content. High percentage of polluting substance generally prohibited their rejection in the natural environment without precaution. If evaluate the aptitude of these sludge for the treatment, to determine which treatments to make them undergo, estimate the position risks and finally know their possibilities of re-use (agricultural, energy or different). Within this framework that being defined the object of this study. The study consists in studying the effect of heat treatment on the physicochemical and rheological behaviour of the activated sludge of purification steps. Heat treatment of the activated sludge watch which the increase in the temperature causes an increase in the pH and a reduction in the chemical demand for oxygen (DCO), and relationship between volatile matters in suspension and suspended matter (MVS/MES). Concert the aspect rheological for studied sludge, the threshold of constrained decreases with the increase in the temperature in same time the viscosity apparent of sludge decreases according to a law of power with the increase in the temperature. Mots cles: Boues activees - Traitement thermique - Rheologie - DCO - pH -MES - MVS.