Oxidation en phase aqueuse de liqueurs noires de papeterie par l'oxygene moleculaire a temperature et pression elevees.

Abstract

Abstract Wet air oxydation is a physicochemical treatment process for the waste waters having a high organic matter content. Oxydation is achieved in liquid phase by mean of molecular oxygen under high temperature and pressure (470 K to 600 K, 3 to 20 MPa). The process was applied to paper‐mill black liquors from annual plants. Their high silica content makes not suitable the usual Kraft process involving combustion after drying. The research led to determine : the heat of oxydation as a function of temperature, the role of the vapor phase, the dependency of the chemical reaction rate on the temperature and on the oxygen partial pressure, a mathematical model for the oxydation kinetics. Chemical composition change of the medium indicated that numerous organic compounds yield to acetate which is an intermediary difficult to oxydize. The whole of the results obtained is to be considered as the main step for the design of an oxydation reactor involving this process.