Coagulation settling apparatus and flocculation settling method

摘要

An object of the present invention is to form a pellet having a high sedimentation rate by suppressing the addition amount of an inorganic coagulant, and efficiently reduce COD, remove a chromaticity component, and the like. A coagulation / sedimentation apparatus 1 comprises a first reaction tank 3 including means 6 for adding an inorganic coagulant to water to be treated, and means 7 for adding an organic coagulant to water to be treated; Means for adding a first polymer flocculant to the water to be treated, located in a section between the sedimentation tank 5 located downstream of the reaction tank 3 and the first reaction tank 3 to the front of the precipitation tank 5 And 10. The precipitation tank 5 stirs the treated water to which the inorganic coagulant, the organic coagulant, and the first polymer coagulant are added, thereby forming a flocculated floc and granulating and concentrating the flocculated floc, thereby producing The particulate concentrated flocculated floc is separated from the treated water. [Selected figure] Figure 1