Treatment of wastewater containing phosphorous and nitrogen

• US 20060249449A1
• Filed: 05/03/2005
• Published: 11/09/2006
• Est. Priority Date: 05/03/2005
• Status: Active Grant

• Current Assignee: University of Western Ontario
• Original Assignee: University of Western Ontario
• Inventors: Nakhla, George, Patel, Jigneshkumar
• Granted Patent: US 7,326,343 B2
• Time in Patent Office: Days
• US Class Current: 210/605
• CPC Class Codes: C02F 3/1273 Submerged membrane bioreactors
• CPC Class Codes: C02F 3/308 Biological phosphorus removal
• CPC Class Codes: Y02W 10/10 Biological treatment of water, waste water, or sewage
• CPC Class Codes: Y10S 210/903 Nitrogenous
• CPC Class Codes: Y10S 210/906 Phosphorus containing

Abstract

A method and process for the treatment of wastewater containing phosphorous and nitrogen. The wastewater is first anaerobically treated to produce an anaerobic effluent from which insoluble organic carbon is separated to form a sludge rich in organic carbon that is used as a substrate during anoxic treatment of the wastewater by de-nitrifying phosphorous accumulating organisms (DPAO'"'"'s) and ordinary de-nitrifying organisms. The separation of insoluble organic carbon is normally conducted using a clarifier located intermediate the anaerobic and anoxic bio-reactors. In one embodiment, the ammonia rich clarifier supernatant is directed to an aerobic reactor for nitrification and the nitrate produced is recycled to the anoxic bio-reactor. The final effluent may be membrane filtered to retain nitrifying biomass within the aerobic bio-reactor. The invention reduces overall hydraulic residence time and sludge volume, which results in a smaller, less expensive wastewater treatment system.

Claims

1. A wastewater treatment process comprising:

a) providing a wastewater to an anaerobic bio-reactor;

b) removing soluble organic carbon from the wastewater in the anaerobic bio-reactor;

c) providing an anaerobic bio-reactor effluent to a clarifier;

d) separating a clarifier sludge comprising insoluble organic carbon from the anaerobic bio-reactor effluent in the clarifier and creating a clarifier supernatant comprising ammonia;

e) providing the clarifier sludge to an anoxic bio-reactor; and

,

f) directing the clarifier supernatant for further treatment other than in the anoxic bio-reactor.

2. The process according to claim 1, wherein the process further comprises:

g) creating an anoxic biomass in the anoxic bio-reactor, the anoxic biomass rich in phosphorous; and

,

h) recycling the anoxic biomass to the anaerobic bio-reactor.

3. The process according to claim 2, wherein the process further comprises:

i) providing the clarifier supernatant comprising ammonia to a suspended growth aerobic bio-reactor; and

,

j) nitrifying the ammonia from the clarifier supernatant in the aerobic bio-reactor.

4. The process according to claim 3, wherein the process further comprises:

k) creating an aerobic biomass in the aerobic bio-reactor; and

,

l) recycling the aerobic biomass to the anoxic bio-reactor.

5. The process according to claim 4, wherein the process further comprises:

m) providing an anoxic bio-reactor effluent comprising residual nitrogen to the aerobic bio-reactor; and

,

n) treating the residual nitrogen from the anoxic bio-reactor effluent in the aerobic bio-reactor.

6. The process according to claim 5, wherein the process further comprises:

o) creating an aerobic bio-reactor effluent in the aerobic bio-reactor; and

,

p) filtering the aerobic bio-reactor effluent using a filter means.

7. The process according to claim 6, wherein the filter means comprises a membrane filter.

8. The process according to claim 6, wherein the filter means is located within the aerobic bio-reactor.

9. The process according to claim 2, wherein an anaerobic biomass is produced in the anaerobic bio-reactor, the anaerobic biomass being rich in sorbed organic carbon.

10. The process according to claim 1, wherein the anoxic bio-reactor contains a microbial population comprising de-nitrifying phosphorous accumulating organisms (DPAO'"'"'s).

11. A method of treating wastewater comprising:

a) anaerobically treating the wastewater to remove soluble organic carbon therefrom to produce an anaerobically treated effluent;

b) separating a sludge comprising insoluble organic carbon from a liquid fraction of the anaerobically treated effluent; and

,

c) anoxically treating the sludge separately from the liquid fraction.

12. The method according to claim 11, wherein each step is performed sequentially and separately.

13. The method according to claim 11, wherein the anoxic treatment of the sludge produces an anoxic biomass that is rich in phosphorous.

14. The method according to claim 13, wherein the method further comprises recycling the anoxic biomass for anaerobic co-treatment with the wastewater.

15. The method according to claim 11, wherein the anoxic treatment of the sludge is performed by a microbial population comprising de-nitrifying phosphorous accumulating organisms (DPAO'"'"'s).

16. The method according to claim 11, wherein the liquid fraction comprises ammonia and wherein the method further comprises aerobically treating the liquid fraction.

17. The method according to claim 16, wherein the aerobic treatment produces an aerobic biomass and wherein the method further comprises anoxically co-treating the aerobic biomass with the sludge.

18. The method according to claim 16, wherein the anoxic treatment produces an anoxic treatment effluent and wherein the method further comprises aerobically co-treating the anoxic treatment effluent with the liquid fraction.

19. The method according to claim 16, wherein the aerobic treatment produces an aerobic treatment effluent and wherein the method further comprises filtering the aerobic treatment effluent using a filter means.

20. The method according to claim 19, wherein the filter means comprises a membrane filter.