Biological nitrogen removal method of septic tank sludge

摘要

PURPOSE: To provide a method for biological removal of nitrogen from sludge in a water purifier tank wherein an additional amount of an organic material necessary for denitrification can be reduced, and an generated amount of excess sludge can be decreased. CONSTITUTION: Sludge 1 in a water purifier tank and sludge 23 to be treated with ozone, separated in a solid liquid separator 21 are introduced into an ozone treating tank 24, brought into contact with ozone 25 and treated with ozone. The sludge treated with ozone is introduced into a nitrification- denitrifying tank 27, aerated by air in a state of being mixed in return sludge 28, and nitrification and denitrification are simultaneously carried out. The nitrification-denitrified sludge is introduced into a solid liquid separator 21 to separate solid from liquid, and the separated liquid is discharged as treated liquid 11. A part of the separated sludge 22 is returned as return sludge 28 into the nitrification-denitrifying tank 27, and the residue (excess sludge) is returned as the sludge 23 to be treated with ozone into a storage tank 2.