Enhanced activated sludge treatment
OwnerMichael T. Ungerinventor
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Abstract
An enhanced activated sludge wastewater treatment method increases volumetric pollutant loading, hydraulic loading capacity and nutrient removal efficiency at a conventional activated sludge wastewater treatment plant. The method describes the control of return activated sludge rates, and the operation of partitioned aeration and reaeration zones according to measured properties of the mixed liquor to achieve the claimed benefits. Operating an existing treatment plant according to the enhanced treatment method provides a more consistent treatment process that is resistant to shock loading and increases plant capacity without the need for costly construction and operation of additional reactors and clarifiers.
Claims12
In a wastewater treatment facility comprising an aeration phase having a plurality of zones, a settling phase, and a digestion phase, an activated sludge wastewater treatment process comprising the steps of:
- partitioning the zones of said aeration phase so that approximately 20% to 45% of the volume of the aeration zones are operated as reaeration zones;
- operating a portion of said reaeration zones in a manner substantially equivalent to the Kraus process wastewater treatment method, said Kraus process comprising the aeration of activated sludge returned from said settling phase and the addition of a portion of the supernatant from said digestion phase;
- returning activated sludge from said settling phase to the upstream portion of said reaeration phase;
- the return activated sludge flow rate typically less than 60% of the wastewater influent flow rate;
- and
- controlling the concentration of mixed liquor suspended solids in said aeration phase so that the typical ratio of MLSS between said reaeration zones and said other aeration zones is equal to or greater than approximately 2:1;
- whereby the process realizes an average influent volumetric loading capacity greater than approximately 3.2 kg BOD5/m3day.
In a wastewater treatment facility comprising an aeration phase having a plurality of zones, a settling phase, and a digestion phase, an activated sludge wastewater treatment process comprising the steps of:
- partitioning the zones of said aeration phase so that approximately 20% to 45% of the aeration zones are operated as reaeration zones;
- operating a portion of said reaeration zones in a manner substantially equivalent to the Kraus process wastewater treatment method, said Kraus process comprising the aeration of activated sludge returned from said settling phase and the addition of a portion of the supernatant from said digestion phase;
- controlling the concentration of dissolved oxygen in said aeration phase so that the typical concentration of dissolved oxygen at the downstream end of said Kraus process aeration zone is generally at least three times the concentration of dissolved oxygen at the downstream end of the other of said reaeration zones;
- returning activated sludge from said settling phase to the upstream portion of said reaeration phase;
- the return activated sludge flow rate typically less than 60% of the wastewater influent flow rate;
- and
- controlling the concentration of mixed liquor suspended solids in said aeration phase so that the typical ratio of MLSS between said reaeration zones and said other aeration zones is equal to or greater than approximately 2:1;
- whereby the process realizes an average influent volumetric loading capacity greater than approximately 3.2 kg BOD5/m3day and an average nutrient removal rate greater than 0.005 lbs nitrogen per lb volatile suspended solids.
Dependencies are inferred from the claim text.