COAGULATION SEDIMENTATION EQUIPMENT AND METHOD

摘要

PROBLEM TO BE SOLVED: To stably and more simply maintain a desirable quality of a treated water as an entire processing system of coagulation sedimentation regardless of the change of a raw water flow.SOLUTION: The objective coagulation sedimentation equipment is provided with: a first agitation tank for adding an inorganic coagulant to a raw water to mix while agitating; a second agitation tank for adding a polymer coagulant and a sedimentation accelerator comprising an insoluble particulate to the raw water to mix while agitating; a flocculation tank for forming floc including the accelerator as a core; a sedimentation tank for precipitating the floc to divide the raw water into a treated water and a slurry; and a cyclone for dividing the slurry extracted from the sedimentation tank into a sludge and the accelerator. The divided accelerator is fed to the second agitation tank, and the divided sludge is discharged. The treated water returning line for returning at least a part of the treated water to the first agitation tank is branched from a treated water transfer line, and at least either flow of the treated water transfer or returning line after branching of the returning line is controlled in response to the raw water flow flowing in the first agitation tank.