| 摘要 |
An object of the present invention is to provide a coagulation sedimentation process for water to be treated in which an inorganic coagulant used in a purified water treatment system is limited to a greater extent than in a conventional technology, and remaining micro flocks and flocks are made greater in density and finer in particle size, thus making it possible to obtain clear water better in quality and also reduce the amount of sludge production. The coagulation-sedimentation process for water to be treated 1 has a micro flocculation step for micro-flocculating in advance fine suspended particles in water to be treated 1, a flocculation step for the micro flocks, and a sedimentation separation step for the flocks, in which as a final stage of the flocculation step, a flock-forming inclined plate 8 whose pitch width is from 5 mm or more to 50 mm or less is provided, and an inorganic coagulant is limited for the used amount so that the turbidity of the water to be treated 1 after passage of the inclined plate 8 at a ratio to that before passage is 4/5 or less, thereby attaining the above object.
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