| 摘要 |
Method and corresponding apparatus for removing oil and grease film from the granular surfaces of particulate media for filtering waste water in waste water filter wherein the filter bed containing said particulate media is provided with an underdrain cavity, which comprises forcing a predetermined quantity of a chemical cleaning agent into the underdrain cavity, forcing a backwashing liquid into the underdrain cavity and up through the filter bed so as substantially to inundate the bed, stopping the flow of backwashing liquid for a predetermined period, hydraulically disturbing said bed of particulate material in contact with said liquid cleaning solution by forcing additional backwashing liquid into said underdrain cavity, stopping the flow of backwashing liquid for a predetermined soaking period, and initiating a predetermined backwash cycle following a predetermined number of soaking cycles. |
