| 摘要 |
PURPOSE:To enable sludge interface to be continuously measured or controlled by the photo detecting outputs of light from light sources by arraying plural photo detectors stepwise in the depth direction of a sedimentation basin and having the light from the light source provided in opposition thereto received in them. CONSTITUTION:When a housing 14 perpendicularly disposed with light sources 25 and photo detectors 28 in opposition is put in a sedimentation basin 1, sludge 4 enters the inside of the housing 14 and the light of the light sources 25 below the sluegd interface 6 is cut off by the sludge 4 and fails to arrive at the opposing photo detectors 28 and the outputs of said photo detectors 28 become zero. On the other hand, at the portions of the supernatant 3 above the sludge interface 6, the outputs of the photo detectors become 1, as a result of which the output signals of the photo detectors 28 become, e.g., 11100...0, and this indicates that the sludge interface 6 exists between the 3rd and 4th photo detectors. |
