Process and apparatus for wet oxidation of wastes

A wet oxidation process for decontaminating a suspension of multi-stream wastes comprising:

• a) preparing a suspension of at least two wastes by:
• i) feeding a sludge suspension having a total dry matter (TDM) comprised between 1% and 18%, produced from organic solid sludges having a TDM comprised between 15 and 40% and wastewaters having a chemical oxygen demand (COD) comprised between 10,000 and 120,000 mg/l, fed into at least one mixing tank comprising at least one agitator;
• ii) mixing said sludges and wastewaters at a rate sufficient to produce a suspension having a TDM comprised between 5 and 18%, and a COD comprised between 10,000 and 150,000 mg/l;
• and
• iii) feeding said suspension into at least one storage tank, and mixing said suspension at a rate sufficient to keep it stable;
• b) preheating the mixed suspension of at least two wastes by injecting at least one direct steam into the suspension;
• c) feeding a stream of the preheated suspension of at least two wastes into a reactor at a temperature of at least 70° C., and at a pressure comprised between 8 bar and 100 bar, wherein said suspension is fed into the reactor by at least one first mixing ejector;
• d) feeding a gas phase stream comprising oxygen and high-pressure steam into said reactor at a pressure comprised between 8 bar and 100 bar and at a temperature comprised between 150° C. and 315° C., wherein said gas phase is fed into the reactor by at least one second mixing ejector;
• e) placing in contact said suspension stream and said gas phase stream into said reactor, so as to flow said streams in countercurrent;
• f) extracting the decontaminated suspension, after oxidation, from a lower bottom of the reactor;
• and
• g) extracting exhaust gases from an upper bottom of the reactor.