Method for treating waste by hydrothermal oxidation

A process for the oxidation of the organic substances present in an aqueous effluent, said aqueous effluent being capable of comprising salts, characterized in that it comprises the following stages:

• said aqueous effluent, comprising a predetermined amount of organic substances, taken under initial pressure and temperature conditions, is injected into a tubular body (18) exhibiting an inlet and an outlet,
• said aqueous effluent is brought to a pressure P1 corresponding at least to the critical pressure of said aqueous effluent, said pressure P1 being greater than the initial pressure,
• said aqueous effluent is brought to a temperature T1 greater than the initial temperature by heating means (38, 22) applied in a zone of said tubular body,
• and in that n fractions of at least one oxidizing composition, the sum of which corresponds to the amount of oxidizing composition necessary for the oxidation of said predetermined amount of organic substances, are injected into said tubular body at n points (24, 30, 32) spaced apart from one another, so that a portion of the thermal energy produced by the oxidation reaction increases the temperature of the reaction mixture from said temperature T1 to the temperature T2>T1 according to an increasing curve (44, 46) between said zone of said tubular body and the nth injection point, whereby said organic substances are oxidized, said reaction mixture continuously evolving from a subcritical liquid state to the supercritical region.