Wastewater treatment system

Patent metadata

Field	Value
Publication number	US-9764973-B2
Application number	US-201414505583-A
Country	US
Kind code	B2
Filing date	Oct 3, 2014
Priority date	Oct 3, 2014
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

A system and method for treating wastewater includes two or more biological reaction zones separated by chamber walls. The system and method for treating wastewater includes static recycle of a mixed liquor from a second biological reaction zone to a first biological reaction zone.

First claim

What is claimed is:

1. A process for treating wastewater, comprising the steps of:
introducing wastewater at an influent velocity through an inlet into an outer aerated anoxic zone wherein the wastewater undergoes nitrification/denitrification;
moving an activated sludge and forming a first mixed liquor having a height in the aerated anoxic zone;
allowing the first mixed liquor to flow into an inner aerobic zone through an outlet;
forming a second mixed liquor in the aerobic zone, the second mixed liquor having a height in the aerobic zone, wherein the height in the aerobic zone is lower than the height in the aerated anoxic zone;
statically redirecting a first portion of the second mixed liquor from the aerobic zone to the aerated anoxic zone through an opening at a flow rate of two to four times the influent velocity;
transferring a second portion of the second mixed liquor from the aerobic zone to a settling zone;
withdrawing an effluent stream from the settling zone;
measuring a total nitrogen content of the effluent stream;
comparing the measured nitrogen content to a target nitrogen content; and
recycling the effluent stream from the settling zone to the aerobic zone when the measured nitrogen content exceeds the target nitrogen content.

2. The process according to claim 1 , wherein the wastewater comprises a nitrogen-containing compound.

3. The process according to claim 1 , wherein the wastewater comprises a phosphorous-containing compound.

4. The process according to claim 1 , wherein the aerated anoxic zone and the aerobic zone are concentric.

5. The process according to claim 4 , wherein the aerated anoxic zone and the aerobic zone are in a racetrack configuration.

6. The process according to claim 4 , wherein the aerated anoxic zone and the aerobic zone are in a circular configuration.

7. The process according to claim 1 , further comprising providing an oxygen-containing gas to the aerated anoxic zone.

8. The process according to claim 7 , wherein the oxygen-containing gas is provided by an aerator.

9. The process according to claim 8 , wherein the aerator is a disc aerator.

10. The process according to claim 1 further comprising allowing a third portion of the second mixed liquor to flow into an anaerobic zone and forming a third mixed liquor.

11. The process according to claim 10 , further comprising statically redirecting at least a portion of the third mixed liquor to the aerobic zone.

12. The process according to claim 1 , further comprising placing a baffle at a predetermined location between the aerated anoxic zone and the aerobic zone.

13. The process according to claim 1 , further comprising withdrawing activated sludge from the second mixed liquor to form a settled sludge.

14. The process according to claim 13 , further comprising recycling at least a portion of the settled sludge to the aerated anoxic zone.

15. A process for recycling mixed liquor in an oxidation ditch having multiple adjacent moving biological reaction zones, the biological reaction zones sharing a common intermediate chamber wall, wherein the mixed liquor level of an outer aerated anoxic nitrification/denitrification zone is higher than the mixed liquor level of an inner aerobic zone such that the mixed liquor flows from the outer aerated anoxic nitrification/denitrification zone to the inner aerobic zone, the process comprising:
statically redirecting the flow of the mixed liquor in the aerobic zone to the aerated anoxic nitrification/denitrification zone at a fluid velocity of two to four times an influent flow rate;
transferring a portion of the mixed liquor from the aerobic zone to a settling zone;
withdrawing an effluent stream from the settling zone;
measuring a nitrogen content of the effluent stream; and
comparing the measured nitrogen content to a target nitrogen content.

16. The process according to claim 15 , wherein the aerated anoxic zone and the aerobic zone are concentric.

17. The process according to claim 16 , wherein the aerated anoxic zone and the aerobic zone are in a racetrack configuration.

18. The process according to claim 16 , wherein the aerated anoxic zone and the aerobic zone are in a circular configuration.

19. The process according to claim 15 , further comprising recycling the effluent stream from the settling zone to the aerobic zone when the measured nitrogen content exceeds the target nitrogen content.

Assignees

• Evoqua Water Tech Llc

Inventors

• Larsen Thomas J
• Pamperin Mark
• Hartwick John

Classifications

• C02F3/30 Primary

  Aerobic and anaerobic processes · CPC title

• C02F3/302

  Nitrification and denitrification treatment (C02F3/308 takes precedence) · CPC title

• C02F2101/166

  Nitrites · CPC title

• C02F2101/163

  Nitrates · CPC title

• Y02W10/10

  Biological treatment of water, waste water, or sewage · CPC title