Patent ID: 7384555

Claim:
A process for aerobic biological treatment of an aqueous organic waste comprising the steps of: introducing the aqueous organic waste into an aeration tank; aerating the aqueous organic waste in the aeration tank in the presence of a biosludge comprising aerobic microorganisms to form an aerated aqueous suspension in which biosludge is grown from the aqueous organic waste and biosludge is lost by autolysis; withdrawing aerated aqueous suspension from the aeration tank and introducing the withdrawn aerated aqueous suspension into a solid/liquid separation unit; subjecting the aerated aqueous suspension in the solid/liquid separation unit to solid/liquid separation to form a separated sludge and a separated liquid phase; discharging the separated liquid phase from the process as treated water; recycling at least a portion of the separated sludge back to the aeration tank; extracting a part of the aerated aqueous suspension from the aeration tank or another portion of the separated sludge; ozonizing either the extracted part of aerated aqueous suspension or the extracted another portion of the separated sludge in an ozonization vessel to ozonize and convert biosludge contained in the extracted part of aerated aqueous suspension or the extracted another portion of the separated sludge into BOD components, the ozonizing taking place at a pH of 5 or lower; and recycling either the ozonized part of aerated aqueous suspension or the ozonized portion of the separated sludge back to the aeration tank for aerobic biological treatment, wherein the amount of biosludge ozonized and converted into BOD components is greater than the difference between the amount of biosludge grown in the aeration tank and the amount of biosludge lost by autolysis.