| 摘要 |
PROBLEM TO BE SOLVED: To enhance the water cleaning capacity of a water cleaning plant. SOLUTION: Caustic soda is charged in the flocculant reaction tank 13 succeeding to a raw water tank 11 and a carbon dioxide reactor 12 to adjust the pH of raw water to 7-7.5 and 200-600 ppm of PAC and about 0.4 ppm of a cationic polymeric flocculant are charged in raw water. About 0.8 ppm of an anionic polymeric flocculant is charged in a flocculation and sedimentation tank 15 and a part of sedimented sludge is returned to the floccurant reaction tank 13 from a slurry tank 17 to always control the turbidity of raw water to about 5,000 ppm. By fitting pH and turbidity to the optimum reaction conditions of the flocculants, a high-degree water quality standard can be satisfied without performing filtering treatment.
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