| 摘要 |
PROBLEM TO BE SOLVED: To provide a production method of a novel starch based coagulant aid being perfectly safe to a human body, through it is used to water purification treatment for producing drinking water, excellent in coagulation effect, and also eliminating trouble of gelation like activated silica, and a use method of the flocculation auxiliary. SOLUTION: The coagulation aid for water purification treatment consisting of an aqueous solution is produced by stirringβ-starch and caustic alkali under the condition of 12.8-13.5 pH to produce a pasty aqueous solution, and then aging it until rotational viscosity of the aqueous solution at the 3% starch concentration becomes <=50 mpa.s. As the coagulation treatment method in the water purification treatment, ferric chloride is added to raw water for purification treatment, then the aged starch aqueous solution is added under the condition of a 0.03-0.5 (starch pouring ratio/Fe Cl3 pouring ratio) ratio and stirred.
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