BIOLOGICAL DENITRIFYING AND DEPHOSPHORIZING METHOD FOR WASTE WATER

摘要

PURPOSE:To efficiently remove the BOD, nitrogen and phosphorus in waste water by introducing a part of the nitrifying liquid of a nitrifying tank to a denitrifying tank and introducing a part of the denitrifying liquid of the denitrifying tank and a part of the sludge separated in a solid-liquid sepn. tank into an anaeration tank. CONSTITUTION:A part of the denitrifying liquid in a 1st denitrifying tank 7 is circulated to the anaeration tank 5 and the balance is introduced into the nitrifying liquid 8 under an aerobic condition where the NH3 in the liquid is nitrified to NOx<->. The greater part of the nitrifying liquid is circulated to the 1st denitrifying tank 7 and the balance is introduced into the 2nd denitrifying tank 9 where the NOx<-> in the liquid is denitrified. The waste water can be denitrified by adding org. matter 10 such as methanol as a reducing agent to the tank 9 at need. The effluent of the 2nd denitrifying tank 9 is subjected to the removal to the BOD component remaining in the liquid again in the anaeration liquid 11; thereafter, the activates sludge is settled and separated in a settling tank 12. The greater part of the sludge is returned as return sludge 2 and part thereof is treated and disposed as surplus activated sludge 13.