| 摘要 |
In a long vertical shaft sewage circulation waste treatment process where influent waste is introduced into the shaft through a downcomer conduit, an improvement is provided whereby the downcomer conduit, because of its flexible construction, is made to collapse by the application of external pressure from surrounding fluid waste in the shaft. Such collapse acts as a check valve which pinches closed the influent conduit and prevents reversal of flow in the circulation system. External pressure collapse of the flexible conduit is produced by a pressure differential between influent within the conduit and the surrounding fluid waste caused, for example, by flow interruption or power failure. The need to employ mechanical check valves, which are subject to malfunction, is eliminated.
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