To control a concentrated sludge concentration by determining the order of priority of a chemical dose, the number of revolution of a screw shaft and the number of revolution of an external screen to change stepwise against a fluctuation of a sludge concentration.
An apparatus controls the chemical dosing ratio, the number of revolution of the screw shaft and the number of revolution of the external screen by placing an electric power detector (24) on a sludge receiving tank (20) of concentrated sludge, receiving an electric signal of the concentrated sludge concentration detected by the electric power detector (24), and placing a discrimination device (28) for computing the data to discriminate it, a controller (29) for receiving a command signal of a discrimination result of the discrimination device (28) to operate an external driver (13) and a screw driver (14), a proportional setting device (30) for receiving a discrimination signal of the discrimination device (28) to increase and decrease the chemical dosing ratio (α) of a flocculent and a controller (31) for receiving a command signal from the proportional setting device (30) to operate a polymer supply pump (18). The concentrated sludge concentration is maintained at a most suitable value, a chemical consumption can be reduced and a treatment process after concentration is easily controlled.
KATAYAMA MASAYOSHI
KAWASAKI HIROICHI
