Aeration septic tank

Claim 1

An aeration septic tank comprising an outer tubular shell extending longitudinally for substantially the full length of the tank, said shell being formed of a relatively thin plastic material molded with a plurality of longitudinally spaced circumferentially extending corrugations, first and second end walls, each respectively secured to and sealing opposite ends of said tubular shell, each said end wall being formed of a relatively thin sheet of plastic material and each being molded with a plurality of mutually spaced corrugations extending across the end wall, each said end wall being molded with a substantially continuous peripheral stiffening rim, said stiffening rim being formed with an exterior surface that mates with a peripheral end portion of an end corrugation of the corrugations of said tubular shell, and means for securing and sealing said end corrugations and said end wall rims to each other, a pair of intermediate bulkheads secured to and within said tubular shell at points mutually spaced from each other and from each of said end walls, said first and second intermediate bulkheads separating said tank into first, second and third chambers collectively adapted to receive and retain sewage to be treated and under treatment at a predetermined liquid level therein, a plurality of stiffening beams extending longitudinally of said tubular shell and secured thereto, an intake conduit having an inlet portion and a discharge portion mutually connected by an elbow, said inlet portion being sealed to said first end wall and extending therethrough, said discharge portion extending within said first chamber generally downwardly to a point considerably below said predetermined liquid level whereby sewage entering the tank is discharged into said first chamber well below the surface of sewage contained therein at said predetermined level, a conduit extending through said first intermediate bulkhead to provide liquid communication between said first and second chambers, said conduit having an intermediate portion substantially at said predetermined level and having a first end portion terminating within said first chamber at a point below said predetermined liquid level whereby sewage will flow from a point below the surface of sewage contained in said first chamber through said first intermediate bulkhead into said second chamber, means for aerating contents of said second chamber, said second intermediate bulkhead being formed with an opening therein that extends across said tank in a direction substantially parallel to the surface of sewage contained therein, opposite end portions of said opening being spaced inwardly of the outer edges of said second intermediate bulkhead, said opening being positioned adjacent the bottom of said second intermediate bulkhead but spaced upwardly therefrom whereby said second intermediate bulkhead has a continuous unbroken peripheral portion to enhance structural rigidity and attachment thereof to said tubular shell, and means for dividing said third chamber into two settling and clarifying compartments, said last mentioned means comprising a panel having a lower end portion secured to the lower edge of said opening of said second intermediate bulkhead and extending from said second intermediate bulkhead within said third chamber upwardly toward said second end wall, said panel having its upper end spaced inwardly of said second end wall to provide a space for material suspended in liquid within said third chamber to settle downwardly along said second end wall and between said panel and said second end wall, said panel having an inclined surface facing said second intermediate bUlkhead whereby matter suspended in liquid of said third chamber above said panel will settle upon said inclined surface and tend to move along said inclined surface toward said opening of said second intermediate bulkhead, and a discharge conduit sealed to and extending through said second end wall substantially at said predetermined liquid level.