Method for wet oxidation of effluents heated essentially by self-combustibility, and corresponding installation

A method for treating a liquid effluent containing dissolved or suspended solids, the method comprising:

• concentrating the liquid effluent to produce a concentrated liquid effluent having approximately 4% to approximately 20% dry matter;
• directing the concentrated liquid effluent having a temperature at or below 90° C. and containing organic matter to a phase separation reactor, wherein the concentrated liquid effluent has not been heated with an indirect heat exchanger prior to entering the phase separation reactor;
• oxidizing at least a portion of the organic matter in the effluent in the phase separation reactor with an oxidizing gas at a temperature ranging between approximately 100° C. and approximately 350° C. and at a pressure ranging between approximately 1 bar and approximately 160 bar, wherein oxidizing at least the portion of organic matter in the effluent forms a gaseous phase and produces heat;
• separating the gaseous phase from the effluent throughout the phase separation reactor and generally maintaining the gaseous phase separate from the effluent in the phase separation reactor;
• heating the effluent in the phase separation reactor with the heat produced from the oxidation of the organic matter;
• directing a treated liquid effluent from the reactor to a steam production unit and producing steam;
• and
• heating the effluent with the steam in a mixing tank such that the effluent directed into the reactor has a temperature at or below 90° C.