| 摘要 |
In the particular embodiment of the invention described in the specification, a liquid to be purified passes first through a screen, a sand trap, a first sedimentation basin, an aeration basin and a second sedimentation basin, and then through a final purification step for chemical admixture and passage upwardly through a particulate filter bed. The particulate filter material is circulated continuously from the bottom of the filter bed through a washing device and the cleaned particulate material is deposited at the top of the filter bed. Sludge collected from the sedimentation basins and the washing device is treated in thickeners and digesters. |
