process and apparatus for purifying domestic sewage under prolonged aeration

摘要

Procedure and devices for the treatment of sewage, deriving from small isolated communities or residences, comprise: a) introducing the sewage into an annular zone, delimited by a cylindrical inside wall (4) consisting of a relatively large mesh screen, preventing the direct passage of the coarse organic material into the inside aerated zone of the tank (1), the zone and the cylindrical one, inside, communicating in the annular lower part so that the coarse organic material of higher specific gravity is deposited on the common bottom of the two zones; b) blowing air into the lower section of the inside cylindrical zone helps the bacterial growth and the aerobic attack of the material organic and allows the material to rise up because the action of the bacterial digestion and the absorption of the fermentation gases reduce its specific weight; c) maintaining the sewage in concentric zones, defined by two screens (13,14), one of average mesh size, the other of small mesh size, preventing the exit of the solid organic material of dimensions greater than the mesh until this solid organic material, due to the attack of the aerobic micro-organisms, under extended aeration, has reached lower dimensions than those of the smaller mesh screen, the material subjected to bacterial digestion being maintained inside the upper annular zones under agitation by air blown into the zone defined by the two screens in order to help the growth of the bacterial flora.