Method for treating wastewater

• US 7,722,769 B2
• Filed: 05/09/2008
• Issued: 05/25/2010
• Est. Priority Date: 10/05/2005
• Status: Expired due to Fees

• Current Assignee: Evoqua Water Technologies LLC (Xylem, Inc.)
• Original Assignee: Siemens Water Technologies Corp (Siemens AG)
• Inventors: Liu, Wenjun, Jordan, Edward J.
• Primary Examiner(s): Barry; Chester T
• Application Number:
  US12/118,262
• Publication Number:
  US 20080264855A1
• Time in Patent Office: 746 Days
• Field of Search: 210/616
• US Class Current: 210/616
• CPC Class Codes: C02F 2209/42 Liquid level
• CPC Class Codes: C02F 3/085 Fluidized beds
• CPC Class Codes: C02F 3/10 Packings; Fillings; Grids packing elements in general B01J19/30, B01J19/32
• CPC Class Codes: C02F 3/1273 Submerged membrane bioreactors
• CPC Class Codes: C02F 3/301 Aerobic and anaerobic treatment in the same reactor
• CPC Class Codes: Y02W 10/10 Biological treatment of water, waste water, or sewage
• CPC Class Codes: Y10S 210/906 Phosphorus containing

Abstract

This invention is directed to a wastewater treatment system having a fluidizable media carrying anoxic bacteria in a first treatment zone and a filter membrane positioned in a second treatment zone. A wastewater is contacted with the fluidizable media and further contacted with air and a filter membrane.

Claims

1. A method of treating wastewater comprising:

contacting a wastewater with anoxic bacteria immobilized on a fluidized media to produce a first water product;

contacting at least a first portion of the first water product with air to form a second water product;

passing the second water product through a filter membrane to produce a filtrate and a concentrated mixed liquor comprising dissolved oxygen;

removing at least a portion of the dissolved oxygen from the concentrated mixed liquor to form a reduced oxygen content concentrated mixed liquor;

contacting at least a second portion of the first water product with the reduced oxygen content concentrated mixed liquor to form a secondary wastewater; and

contacting the secondary wastewater with the anoxic bacteria immobilized on the fluidized media.

2. The method of treating wastewater of claim 1, further comprising contacting a portion of the secondary wastewater with the anoxic bacteria fixed on the fluidized media.

6. The method of claim 1, wherein contacting the wastewater with anoxic bacteria comprises contacting the wastewater with denitrifying bacteria.

7. The method of claim 1, wherein contacting the wastewater with anoxic bacteria immobilized on the fluidized media comprises contacting the wastewater with the anoxic bacteria immobilized on a fluidized media having a specific gravity substantially equal to a specific gravity of the wastewater.

3. A method of treating wastewater comprising:

passing a wastewater through a fluidized media carrying anoxic bacteria to produce a first treated wastewater;

passing a first portion of the first treated wastewater through a membrane module comprising a filter membrane to produce a filtrate and a concentrated mixed liquor comprising dissolved oxygen;

discharging the filtrate;

removing at least a portion of the dissolved oxygen from the concentrated mixed liquor to form a reduced oxygen content concentrated mixed liquor;

combining a second portion of the first treated wastewater with the reduced oxygen content concentrated mixed liquor to form a secondary wastewater; and

contacting the secondary wastewater with the fluidized media carrying anoxic bacteria.

4. The method of treating wastewater of claim 3, further comprising passing a portion of the secondary wastewater through the fluidized media.

5. The method of treating wastewater of claim 3, wherein passing the first portion of the first treated wastewater through the membrane module occurs under hydrostatic pressure.

8. The method of claim 3, wherein passing the wastewater through a fluidized media carrying anoxic bacteria comprises passing the wastewater through a fluidized media carrying denitrifying bacteria.

9. The method of claim 3, wherein passing the wastewater through the fluidized media comprises passing the wastewater through a fluidized media having a specific gravity substantially equal to a specific gravity of the wastewater.