| 摘要 |
<p>PURPOSE:To provide an operation method for a natural filter wherein a turbid layer suspending above the upper surface of a filter layer can be effectively broken to pieces to effect washing. CONSTITUTION:Raw water in a filter tank is discharged to lower the water level in the filter tank to a level below the upper surface of a filter layer 26, and washing water is sprayed, in the air, against a turbid layer suspending above the filter layer by means of a surface washing device 25 disposed above the filter layer 26, whereby a direct surface washing process, wherein the turbid layer suspending above the filter layer is broken, washed, and removed, is carried out.</p> |
