Method for wet combustion of organic material

In the wet combustion method of combusting organic material including oxidation-resistant substances of lignocellulosic origin comprising low-molecular-weight acids which comprising the group including acetic acid proprionic acid or salts thereof, dissolved or suspended in a liquid comprising waste liquor obtained from wood pulping processes in which the organic material is oxidized by contact with air or oxygen at a temperature ranging between 180.degree. C. and 340.degree. C. and at a correspondingly superatmospheric pressure, the improvement comprising:

• (a) a first oxidizing step, in which the organic material is partially oxidized by introducing into said liquid a molecular oxygen at a temperature and superatmospheric pressure and in an amount corresponding substantially to the theoretical value required to release a portion on the order of 75%-95% of the total heat value of said organic material;
• (b) a second oxidizing step, in which high temperature superatmospheric molecular oxygen is introduced into said liquid in an amount in excess of the theoretical value sufficient to oxidize the residual oxidation-resistant substances and to impart to the effluents generated in said second step a molecular oxygen content sufficient to achieve the partial oxidation in said first step;
• and
• (c) feeding the thus oxygenated effluents to said first step.