Granted Patent B2

US 7,105,091 · App. 10/985,265 · Granted Sep 12, 2006

Abstract

Claims (103)

1. A method of treating wastewater, the method comprising the steps of:

conducting wastewater to a treatment vessel for treatment comprising contact with a first biological population having a first-biological population profile to produce a mixed liquor including activated sludge;

separating the activated sludge from the mixed liquor;

drawing off a first portion of the separated activated sludge and returning said first portion to the treatment vessel;

drawing off a second portion of the separated activated sludge and adding that second portion to at least one off-line treatment area;

controlling the off-line treatment area so as to produce, in the off-line treatment area, a second biological population having a second-biological population profile different from the first-biological population profile; and

returning at least a fraction of the produced second biological population to the treatment vessel, wherein the second biological population achieves lower solids levels.

2. The method of claim 1 , wherein the step of returning at least a fraction of the produced second biological population includes decanting a percentage of the produced second biological population from the off-line treatment area.

3. The method of claim 1 , wherein the step of returning at least a fraction of the produced second biological population includes removing a percentage of the produced second biological population from the off-line treatment area.

4. The method of claim 1 , wherein wastewater is combined with the second portion of activated sludge in the off-line treatment area.

5. The method of claim 1 wherein controlling the off-line treatment area comprises:

i. mixing the second drawn-off portion without aeration to achieve anaerobic conditions without substantial sulfide generation;

ii. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes; and

iv. mixing without aeration to achieve anaerobic conditions.

6. The method of claim 1 wherein controlling the off-line treatment area comprises:

i. mixing the second drawn-off portion without aeration to achieve anaerobic conditions without substantial sulfide generation;

ii. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes;

iii. mixing without aeration to achieve anaerobic conditions;

iv. allowing settling to produce a decantable volume; and

v. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes.

7. The method of claim 1 wherein controlling the off-line treatment area comprises:

i. mixing the second drawn-off portion without aeration to achieve anaerobic conditions without substantial sulfide generation;

ii. stopping the mixing for a period of time;

iii. mixing; and

iv. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes.

8. The method of claim 1 wherein controlling the off-line treatment area comprises:

i. mixing the second drawn-off portion of wastewater without aeration to achieve anaerobic conditions without substantial sulfide generation;

ii. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes; and

iii. stopping the aeration but continuing the mixing.

9. The method of claim 1 wherein controlling the off-line treatment area comprises:

i. mixing the second drawn-off portion of wastewater without aeration to achieve anaerobic conditions without substantial sulfide generation;

ii. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes;

iii. stopping the aeration but continuing the mixing;

iv. allowing settling; and

v. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes.

10. A method for treating wastewater in a wastewater treatment system including a first treatment vessel for receiving wastewater and for treatment including contact with a first biological population having a first-biological population profile, the method comprising the steps of:

drawing off a portion of the first biological population and adding said drawn-off portion to an off-line treatment area;

controlling the off-line treatment area to produce a second biological population having a second-biological population profile different from the first-biological population profile, such controlling including sequentially subjecting the off-line treatment area portion to one of aerobic conditions, anoxic conditions and anaerobic conditions followed by subjecting the off-line treatment area to at least one of aerobic conditions, anoxic conditions and anaerobic conditions; and

returning at least a portion of the second biological population to the treatment vessel.

11. The method of claim 10 , wherein the step of returning at least a fraction of the produced second biological population includes decanting a percentage of the produced second biological population from the off-line treatment area.

12. The method of claim 10 , wherein the step of returning at least a fraction of the produced second biological population includes removing a percentage of the produced second biological population from the off-line treatment area.

13. The method of claim 10 , wherein wastewater is combined with the drawn-off portion of the first biological population in the off-line treatment area.

14. The method of claim 10 wherein controlling the off-line treatment area comprises:

i. mixing the drawn-off portion without aeration to achieve anaerobic conditions without substantial sulfide generation;

ii. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes; and

iv. mixing without aeration to achieve anaerobic conditions.

15. The method of claim 10 wherein controlling the off-line treatment area comprises:

i. mixing the drawn-off portion without aeration to achieve anaerobic conditions without substantial sulfide generation;

ii. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes;

iii. mixing without aeration to achieve anaerobic conditions;

iv. allowing settling to produce a decantable volume; and

v. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes.

16. The method of claim 10 wherein controlling the off-line treatment area comprises:

i. mixing the drawn-off portion without aeration to achieve anaerobic conditions without substantial sulfide generation;

ii. stopping the mixing for a period of time;

iii. mixing; and

iv. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes.

17. The method of claim 10 wherein controlling the off-line treatment area comprises:

i. mixing the drawn-off portion of wastewater without aeration to achieve anaerobic conditions without substantial sulfide generation;

ii. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes; and

iii. stopping the aeration but continuing the mixing.

18. The method of claim 10 wherein controlling the off-line treatment area comprises:

i. mixing the drawn-off portion of wastewater without aeration to achieve anaerobic conditions without substantial sulfide generation;

ii. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes;

iii. stopping the aeration but continuing the mixing;

iv. allowing settling; and

v. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes.

19. A method of treating wastewater, the method comprising the steps of:

combining wastewater and a first biological population having a first-biological population profile in a treatment vessel;

exposing the wastewater and first biological population in the treatment vessel to at least one of an anaerobic, anoxic and aerobic conditions to form a mixture including sludge;

separating the sludge from the mixture;

drawing off a first portion of the separated sludge and returning said first portion to the treatment vessel;

drawing off a second portion of the separated sludge to an off-line treatment area;

controlling the off-line treatment area so as to produce, in the off-line treatment area, a second biological population having a second-biological population profile different from the first-biological population profile, such that the second-biological population profile is customized to minimize the disposal volume of residual solids produced by the treatment of the wastewater; and

returning at least a fraction of the produced second biological population to the treatment vessel.

20. The method of claim 19 , wherein the step of returning at least a fraction of the produced second biological population includes decanting a percentage of the produced second biological population from the off-line treatment area.

21. The method of claim 19 , wherein the step of returning at least a fraction of the produced second biological population includes removing a percentage of the produced second biological population from the off-line treatment area.

22. The method of claim 19 , wherein wastewater is combined with the second portion of separated sludge in the off-line treatment area.

23. The method of claim 19 wherein controlling the off-line treatment area comprises:

i. mixing the second drawn-off portion without aeration to achieve anaerobic conditions without substantial sulfide generation;

ii. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes; and

iv. mixing without aeration to achieve anaerobic conditions.

24. The method of claim 19 wherein controlling the off-line treatment area comprises:

i. mixing the second drawn-off portion without aeration to achieve anaerobic conditions without substantial sulfide generation;

ii. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes;

iii. mixing without aeration to achieve anaerobic conditions;

iv. allowing settling to produce a decantable volume; and

v. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes.

25. The method of claim 19 wherein controlling the off-line treatment area comprises:

i. mixing the second drawn-off portion without aeration to achieve anaerobic conditions without substantial sulfide generation;

ii. stopping the mixing for a period of time;

iii. mixing; and

iv. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes.

26. A The method of claim 19 wherein controlling the off-line treatment area comprises:

i. mixing the second drawn-off portion of wastewater without aeration to achieve anaerobic conditions without substantial sulfide generation;

ii. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes; and

iii. stopping the aeration but continuing the mixing.

27. A The method of claim 19 wherein controlling the off-line treatment area comprises:

i. mixing the second drawn-off portion of wastewater without aeration to achieve anaerobic conditions without substantial sulfide generation;

ii. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes;

iii. stopping the aeration but continuing the mixing;

iv. allowing settling; and

v. mixing with aeration to achieve biological growth conditions without substantial production of obligate aerobes.

Assignments (6)