| 摘要 |
PROBLEM TO BE SOLVED: To improve the properties of filtrate immediately after backwashing. SOLUTION: During the backwashing of a filter 24, a flocculant is added from a flocculant storage tank 34 to backwashing water, and an acid is added to the tank 30. Especially, by setting the pH and amount of the backwashing water in advance, the amount of the flocculant to be adhered to the surface of a filter medium by the backwashing can be adjusted properly so that good filtrate can be obtained even immediately after the backwashing. |
