Apparatus for treatment of sewage

Claim 1

Installation for the treatment of sewage by bacterial digestion comprising a tank having an outer circumferentially extending wall joined with a closed bottom wall, an inner circumferentially extending wall spaced inwardly from said outer wall, the annular space between said inner and outer walls defining peripheral zones for decantation and removal of treated effluents, a centrally disposed vertical chimney means open at both ends, the lower end thereof being in communication with liquid adjacent the bottom of the tank, said chimney means including means for circulating liquid upwardly through the chimney means and means for oxygenating said circulating liquid, whereby oxygenated liquid will be circulated downwardly in the space between said chimney means and said inner wall and recirculated through the chimney means, the lower portion of the outer wall being defined by a reversed truncated cone, the lower margin of the inner wall being spaced from the bottom of the tank to permit flow of treated effluent peripherally upwardly into said zones of decantation and removal, the lower portion of the space between the inner and outer walls being subdivided into a plurality of upwardly directed conduits, inlet means to conduct sewage into space within said inner circumferential wall, and outlet means communicating with said zone of decantation for removal of treated effluent.