| 摘要 |
Filter cassette (1) adapted to be sealingly mounted against the inner wall of a well or a well cover so as to extend radially across the cross section of the well, comprising a ring-shaped space to be filled or refilled with an absorbing or active additive and a lid (5) extended radially from the area of the inner wall of the well towards a central hole (7), and an opened bottom (11), the filter cassette having a capacity to receive water streaming down that increases gradually in the radial direction mentioned and comprising a lid with a top surface, as seen in a radial direction from the periphery to the centre of the lid, which rises gradually over a horizontal plane on which the lid rests. |
