Aeration apparatus and method

Claim 1

In an apparatus for treating waste water with a gas such as air, oxygen or other oxygen containing gas in an activated sludge aeration process including: (a) an outer mixing vessel; (b) outlet means from said outer mixing vessel for continuous withdrawal of mixed gas and waste water which form the contents of said outer mixing vessel; (c) a pre-mixing draft tube substantially vertically axially aligned within said outer mixing vessel and having an upper end and a lower end; (d) a nozzle opening at the lower end of said draft tube; (e) mixing means for mixing the contents of said outer mixing vessel with incoming raw waste water and recycled activated sludge, said mixing means connected to the upper end of said draft tube and supplying the contents, raw waste water and activated sludge to said draft tube; (f) said mixing means comprising a trough means for receiving the raw waste water and recycled activated sludge and a conduit means connecting said trough means to said draft tube, said conduit means having a funnel opening therein located within the contents of said outer mixing vessel for introducing the contents and the sewage into said draft tube; (g) air inlet means for introducing the air directly into said draft tube between the upper and lower ends thereof for mixing the air with the sewage and contents flowing through the draft tube; and (h) pump means for pumping the mixed contents and liquid through said draft tube; the improvement comprising said conduit means including a loop having a top portion connected to said trough means and a bottom portion within which the funnel opening is located whereby waste water flowing into the trough means initially flows into the loop in opposing directions which eventually converge and the funnel opening is located at the point in the loop where the convergence begins.