Method for treating organic waste, in particular sludge from wastewater treatment plants, and facility for implementing said method

A process for treating organic waste or for treating sludge from wastewater treatment plants, in order to produce energy and/or organic matter which has been rendered hygienic, consisting of:

• a first step of mesophilic or thermophilic digesting of at least one fraction of a stream of organic waste in a first mesophilic or thermophilic digester;
• dehydrating all of the digested and nondigested waste, the dehydration being carried out to 10-20% of dry matter;
• aerated thermal hydrolyzing of the dehydrated waste, with the injection of an oxidizing agent in an amount between 10% and 50% of the stoichiometric amount for the oxidation of the organic matter, and setting to the required temperature via a heater, the oxidizing agent consisting of at least one selected from the group consisting of oxygen, ozone, hydrogen peroxide and air, the injection of oxidizing agent being in stages controlled by measuring CO2 in a headspace of a hydrolysis reactor, the oxidizing agent being injected at several points including a bottom of the hydrolysis reactor and half way up the hydrolysis reactor;
• and
• a second mesophilic or thermophilic digesting of the stream of only hydrolyzed waste in a second mesophilic or thermophilic digester, separate from the first digestion step.