CONTROL METHOD OF DO IN OXIDATION DITCH METHOD

摘要

PURPOSE:To maintain the DO value of sewage at a prescribed value by providing an outflow weir which fluctuates the water level in a discharging channel according to the inflow rate in the outflow part of a circulating water course and fluctuating the aeration rate by the change in the depth of the blade of an aerator on the basis of said fluctuation. CONSTITUTION:An outflow weir 3 is provided to fluctuate the water level in an aeration tank 1 according to an inflow rate in the case in which the sewage to be treated fluctuates in volume with lapse of time. More specifically, the outflow resistance of the weir 3 is set by an operation of moving vertically the notch width at the center of the slit plate 3a of the weir 3 or the plate 3a and outlet 11 by a screw mechanism 3b so that the immersion depth of the blade of the tank 3 attains the displacement in the specified range. The water level in the tank 1 is thus controlled and a specified fluctuation is given to the immersion depth of the blade 2a of the aerator 2. The aeration tank having the shape with which the aeration rate is changed by the blade 2a corresponding to the fluctuation is used.