DEPHOSPHORIZATION DEVICE

PURPOSE:To permit satisfactory removal of the phosphorus carried over into the excess sludge, etc., from an activated sludge treatment, more particularly biological dephosphorization treatment by providing an anaerobic digestion tank and aeration tank for making the aeration treatment of the desorbed liquid and/or sludge from said tank. CONSTITUTION:The anaerobic digestion tank 1 and the aeration tank 2 for making the aeration treatment of the desorbed liquid and/or sludge from the tank 1 are provided. More specifically, the sludge into which the phosphorus of the excess sludge, etc., generated from the activated sludge treatment is taken is anaerobically digested and the desorbed liquid and/or sludge thereof is subjected to the aeration treatment to decarbonize the liquid or sludge and to increase the pH thereof, by which the phosphorus component is settled and separated in the form of ammonium magnesium phosphate. The phosphorus is thereby removed, the phosphorus circulation in the treatment system is interrupted and the substantial removal of the phosphorus is attained.