| 摘要 |
<p>PURPOSE: To prevent the rise of pressure loss by preventing the pressing of a filter material bed to an upper outflow preventing means by supplying washing water in quantity larger than the usual quantity of treated water at first and stopping the supply thereof before and after the upper part of the floating filter material bed reaches the upper outflow preventing means. CONSTITUTION: An ascending flow filter apparatus is packed with a compressive floating filter material and filtering operation is performed for a definite time and, thereafter, filter material washing operation is performed. Water is supplied in quantity about three times the quantity of usually supplied water by a washing pump and, at a point of time when the upper part of the floating filter material bed reaches the position of an upper part outflow preventing means, the supply of water is stopped to return the supply quantity of water to usual supply quantity. By this constitution, the rise of the pressure loss of the filter material bed is prevented and a treatment operation time can be extended and the filter material bed is uniformized.</p> |
