Abstract Apparatus for the surface aeration and circulation of liquid, e.g. for the treatment of sewage comprises an aeration rotor which, in use, is partially submerged in the liquid to be treated and revolves about a vertical axis. The rotor is equipped with a number of flow passageways for the liquid formed between radial blades and spaced upper and lower spaced rotor walls. The flow passageways are curved in their vertical plane by approximately 90* so as to deflect outwardly the liquid entering said flow passageways from below through inlets arranged in a circle around the axis of the rotor the liquid then being discharged radially outwards in substantially horizontal direction through outlet openings arranged on the outer perimeter of the rotor situated on a larger diameter compared with the diameter on which the inlets are arranged. The outer circumference of the portion of the rotor submerged in the liquid is formed as a straight frustoconical surface, said lower rotor wall forming a limiting wall of said curved flow passageway and frustoconical surface defining an annular hollow space extending around the rotor to provide for buoyancy in order to reduce the weight of the rotor when immersed in the liquid in operating position.
Apparatus according to claim 2, in which the discharge end portion of said flow passageways is substantially rectilinear and upwardly inclined towards the outlet opening through an angle relative to the horizontal not exceeding 6*.
Claim 2
Dependent Claim
29 words
Apparatus according to claim 2, in which said hollow space between said circumferential frustoconical surface and said lower curved rotor wall is filled with a lightweight synthetic foam material.
Claim 3
Dependent Claim
95 words
Apparatus according to claim 2, in which said rotor is closed on the top by an annular plate extending from a hub portion of the rotor to the upper edge of the outlets of said flow passageways, and an annular space being provided communicating with the atmosphere by openings provided in said annular top closure plate and with said flow passageways, whereby, due to the suction action of the liquid flowing through said flow passageways, atmospheric air is drawn into said annular space through said openings and mixed with the liquid in the flow passageways.
Claim 4
Dependent Claim
95 words
Apparatus according to claim 5, in which said blades are curved in radial direction and each flow passageway being limited at one side by a convex curvature of a blade and the opposite side by a concave curvature of a blade, said annular space below said annular top plate extending from said hub portion outwardly to said upper rotor wall forming a limiting wall of said flow passageways, said upper rotor wall having openings therein disposed along the concave curvAture of said blades, said openings establishing communication between said hollow space and said flow passageways.
Claim 5
Dependent Claim
33 words
Apparatus according to claim 5, in which said rotor turning about a vertical axis is operatively connected with driving means arranged to drive the rotor in one or the other direction of rotation.