| 摘要 |
When backwashing a rapid filter (1) where water is washed with filter sand, a preset amount of filter sand (5) is sucked from the rapid filter (1) by a pump (2). The sucked filter sand (5) is fed to a sand washing device (3) where the contaminants on the filter sand are removed. Contaminants-removed filter sand (6) is kept in a washed-sand stock tank (4), and stored filter sand (7) is returned to the rapid filter (1) when the rapid filter is backwashed. An automatic washing of filter sand in the rapid filter is possible by repeating the steps of sucking, washing and returning filter sand, whereby a sand washing function is regenerated by a washing method other than surface washing and backwashing to thereby drastically prolong a regenerating cycle of a filter pond. |
