Apparatus for sewage purification

Claim 1

A sewage purification apparatus comprising a vessel for containing a liquid of BOD-containing water and activated sludge and an aerator disposed in the vessel, said aerator comprising: a plurality of settlers each of which is vertically disposed and has an outlet port at the lower end thereof; a plurality of bubblers each of which is disposed in parallel with the corresponding settler and has an inlet port at the lower end thereof; a diffuser in each of said bubblers for blowing an oxygen-rich gas into the liquid in the bubbler so that oxygen is absorbed in the liquid and so that the liquid is caused to rise toward the top of said bubbler; a communication pipe for communicating said bubblers and said settlers for causing the liquid raised in said bubblers to be transferred into said settlers, said communication pipe extending in parallel with the liquid level in said vessel; the upper ends of said settlers and the upper ends of said bubblers all being commonly connected to said communication pipe; said communication pipe having a separator wall which divides the interior of the communication pipe into upper and lower chambers, said upper chamber being communicated with said settlers and said lower chamber being communicated with said bubblers; each of said bubblers having an inner cylindrical member and an outer cylindrical member which are coaxially disposed and supported by said communication pipe, the interior of said inner cylindrical member being communicated with the upper chamber of said communication pipe, and a space defined between said inner and outer cylindrical members being communicated with the lower chamber of said communication pipe; said communication pipe including ports in the lower portion thereof below the liquid level in said vessel for admitting liquid from said vessel into said lower chamber; said outer cylindrical member of each of said bubblers including ports providing communication between said lower chamber and said space; and said inner cylindrical member including ports providing communication between said space and said inner cylindrical member, whereby liquid from said vessel is conducted to each of said bubblers.