Method and apparatus for treating organic wastewater

• US 4,415,452 A
• Filed: 03/18/1982
• Issued: 11/15/1983
• Est. Priority Date: 03/18/1982
• Status: Expired due to Fees

• Current Assignee: Richard W. Heil, Thomas A. Rose
• Original Assignee: Richard W. Heil, Thomas A. Rose
• Inventors: Heil, Richard W., Rose, Thomas A.
• Primary Examiner(s): Castel, Benoit
• Application Number:
  US06/359,585
• Time in Patent Office: 607 Days
• Field of Search: 210/604, 210/608, 210/614, 210/626, 210/627, 210/628, 210/195.3, 210/197, 210/788, 210/199-202, 210/218, 210/220, 210/252, 210/255, 210/512, 210/787
• US Class Current: 210/614
• CPC Class Codes: C02F 1/385 by centrifuging suspensions centrifuges B04B
• CPC Class Codes: C02F 3/006 Regulation methods for biological treatment
• CPC Class Codes: C02F 3/26 using pure oxygen or oxygen-rich gas
• CPC Class Codes: Y02W 10/10 Biological treatment of water, waste water, or sewage

Abstract

A method and apparatus for treating a continuous stream of organic wastewater using highly concentrated activated sludge (10,000 mg/l MLSS), elevated atmospheric pressure, and high levels of dissolved oxygen. The apparatus consists of three pressurized vessels linked in series by piping, and maintained at equal pressure by means of a common manifold.

The first vessel receives the mixed liquor consisting of macerated sewage and return activated sludge and thoroughly aerates it with diffused air bubbles. The liquor then flows by gravity into the second pressurized vessel where flocculation and further aeration occur. From an overflow/transfer box in vessel 2, the liquor flows by gravity into the bottom tier of the third vessel which functions as a cyclone separator. The concentrate is drawn from the bottom of the vessel by a return sludge pump and recycled to the first vessel. The centrate rises into the upper tier of the third vessel where it is clarified and discharged as tertiary quality effluent.

Claims

1. The method of treating organic waste water with activated sludge comprising the steps of:

establishing an enclosed continuous flow way for the organic waste water and the activated sludge in a mixed liquor form including several aeration chambers, and a separator chamber that are air pressurized to a predetermined pressure, that contain organic waste water and activated sludge, and that are consecutively connected in a continuous flow circuit through said aeration chambers, said separator chamber, and return flow to said one aeration chamber,

mixing activated sludge and fresh organic waste water in said return flow,

passing the return flow into said one aeration chamber adjacent the lower end thereof,

dosing the body of the liquor of said one aeration chamber with air in diffused bubble form for flocculating and air saturation of the sludge,

passing continuously from said liquor body a flow of the liquor to a subsequent of said aeration chambers having a second liquor body while diffusing air into said second body from the lower end of same for providing a liquor flow in which the flocculated sludge has assimulated the organic waste in the liquor flow,

continuously passing in a gravity flow to said separator chamber the organic waste assimilated liquor flow, and establishing and maintaining in said separator chamber and in said organic waste assimilated liquor flow a cyclone separating action effecting centrifugal force and gravity induced settling out of the sludge flow thereof to provide said return flow, and a rising effluent centrate flow,

continuously clarifying and discharging the centrate flow as tertiary quality effluent,

and continuously pumping said return flow to effect said mixing and said first mentioned passing steps.

2. The method set forth in claim 1 wherein:

said flow way is pressurized to have a uniform pressure of up to about 35 psig.

3. The method set forth in claim 2 wherein:

said return flow is at a rate of approximately three hundred percent of said effluent centrate flow.

4. The method set forth in claim 2 wherein:

the concentration of the liquor approximates 10,000 mg/l of mixed liquor suspended solids.

5. The method set forth in claim 4 wherein:

said pumping step is effected across a relatively constant differential head.

6. The method set forth in claim 5 wherein:

the concentration of suspended sludge solids of said return flow at the site of said pumping step is monitored,

and the return flow is sludge wasted to approximately maintain said liquor concentration.

7. The method set forth in claim 2 wherein:

the flow of the liquor in said aeration chambers and in said cyclone separating action is quiescent.

8. Apparatus for continuously treating organic waste water with activated sludge as a mixed liquor, said apparatus comprising:

first and second vessels disposed at substantially the same horizontal level respectively defining first and second aeration chambers,

a third vessel disposed substantially at said horizontal level and defining a separator chamber,

said first and second vessels containing the liquor up to a predetermined horizontal level, therein in each, with said first vessel being in liquid flow communication with said second vessel below said predetermined level,

said second vessel being connected to said third vessel chamber for gravity induced liquid flow of the liquor thereinto from said second vessel by conduit means extending from about said predetermined level of said second vessel to a lower level in said third vessel for imparting a velocity head to the liquor flow in said separator,

said third vessel defining at its lower end a funnelling liquid flow discharge outlet and defining an internally centered frusto-conical divider baffle that depends in circumambient relation about said third chamber from above to below said lower level thereof and defines at its lower end a liquid upflow port,

said third vessel above said baffle having means for effluent draw off therefrom,

return conduit means connected between said third vessel outlet and the lower end of said first vessel for returning sludge from said separator chamber to said first chamber including pump means,

inlet conduit means connected to said return conduit means adjacent said first chamber for supplying organic waste water thereto,

said chambers being manifold connected at their upper ends and being commonly pressurized at a level in range of up to about 35 psig,

first means for diffusing air into the liquor of said first chamber at the lower end of said first chamber,

and second means for diffusing air into the liquor of said second chamber at the lower end of said second chamber,

said liquor concentration in said first and second chambers being about 10,000 mg/l MLSS,

said pump means and said return conduit means effecting the return of the sludge therethrough at a rate approximating three hundred percent of the effluent draw off flow.

9. The apparatus set forth in claim 8 including

means shunted across said pump means for monitoring the mixed liquor suspended solids factor of the return sludge from the rheological properties thereof,

and means for wasting sludge from said return sludge for controlling the concentration therein of the such mixed liquor suspended solids.

10. The apparatus set forth in claim 8 wherein:

said first and second air diffusing means are air supplied from the air pressurizing said chambers.