Biological sewage treatment apparatus of the rotary disc type

摘要

A sewage treatment apparatus having a rotary shaft and a plurality of rotary plates secured to the rotary shaft in an axially spaced-apart relationship, each of the rotary plates being adapted to be rotated while it is partly dipped in sewage within a treating tank, a plurality of holding members provided fixedly around the rotary shaft for rotation therewith, and the rotary plates being secured such that at least one rotary plate is fixedly held at its central end portion between every two adjacent holding members.