| 摘要 |
PROBLEM TO BE SOLVED: To provide a flocculation treatment method, in which the water to be treated is made to pass through a first reaction tank and a second reaction tank successively and is treated by using a trivalent iron-based inorganic flocculant so that the necessary amount of the trivalent iron-based inorganic flocculant can be reduced and further high-quality treated water can be obtained stably.SOLUTION: When the trivalent iron-based inorganic flocculant and NaOH are added to the first reaction tank and the lower-limit pH value of such a pH range is defined as X that the water to be treated is treated with the added trivalent iron-based inorganic flocculant to form coagulated flocks in the water to be treated, a control target pH value A of the second reaction tank is set within a range of X-(X+0.3), the control target pH value A' of the first reaction tank is set within another range of A-(A+0.7), and then flocculation treatment is performed. |
