| 摘要 |
<p>The invention relates to a method for washing a filter intended for cleansing a contaminated liquid and comprising a granular bed, a drainage system located beneath the bed, means for introducing first and second liquid flows into the bed, wherein the first liquid flow is operative to fluidize solely upper bed layers at least locally, and the second liquid flow is operative to fluidize the bed throughout the whole of its depth. The novel method is characterized by ejecting the flows of liquid selectively into the bed through orifices which are placed in the bed at a location between the highest point and the lowest point therein and which are substantially equidistant from the upper surface of the bed; and by introducing the first liquid stream into the upper layers of said bed in a smaller quantity and at a corresponding smaller flow rate than the second liquid stream, such that the bed layers located beneath these upper layers will be unaffected by the ongoing bed washing operation.</p> |
