Mixing chamber for thickening sewage sludge by means of a flocculation agent combined with overflow drainage means

Claim 1

A mixing chamber for thickening sludge, especially sludge in a sewage clarification plant by means of agitation and addition of a flocculating agent, in combination with a drainage system to move the sludge out of the mixing chamber, comprising a generally cylindrical housing having a cup-like bottom portion and a widened upper portion; agitating means in said housing defining a mixing zone at the lower portion thereof; an inlet means for raw sewage connected to said bottom portion defining a feeding zone; an inlet pipe within and penetrating into said inlet means of smaller diameter than said inlet means which is adapted to add a flocculating agent to the sludge to thereby cause thickening of said sludge in said mixing zone; the widened upper portion of said housing comprising a perforated inner wall coextensive with the bottom portion of said housing and an outer wall spaced from said inner wall defining an annular chamber; a separate outlet for said annular chamber; said perforated inner wall constituting means for dewatering the thickened sludge in said housing about said annular chamber in a zone directly above the feeding zone and the mixing zone; a dewatering means including pipe means extending from the upper portion of said housing outside of said housing to a drainage system and an outlet on said pipe means to deliver thickened sludge from said mixing chamber to said draining system; and a further drainage means of said drainage system outside of said mixing chamber for further dewatering of said sludge adapted for subsequent storage or conveying of said sludge.