Apparatus and methods for control of waste treatment processes
View Patent ↗Waste-treatment processes are enhanced through generation and introduction of specific biological populations customized to perform or favor specific tasks either during the main process, for the formation or precipitation of certain biological nutrients, or to accomplish solids formation reduction in a post-treatment process. These bacteria may be grown from specialized mixes of activated sludge and waste influent by exposing these materials to controlled environments (e.g., in an off-line treatment area). They may then be returned to the main process to perform certain tasks such as converting particulate cBOD into soluble cBOD for utilization, to reduce high solids yield organisms by supplementing the population characteristics with low yield organism characteristics, to provide biological nutrients or oxygenation assistance, to improve nitrification/denitrification efficiency, or to disfavor filamentous biology such as Norcardia sp.
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 an off-line treatment tank;
controlling the off-line treatment tank so as to produce, in the off-line treatment tank, a second biological population having a second-biological population profile different from the first-biological population profile, wherein the controlling step comprises subjecting the contents of the off-line treatment tank to a selected sequence of at least two conditions selected from the group consisting of an aerobic condition, an anoxic condition and an anaerobic condition, wherein the contents of the off-line treatment tank are maintained at each condition in the sequence for a corresponding determined length of time; 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 relative to the first biological population, and wherein the returned fraction of the produced second biological population contains a higher level of soluble cBOD, nitrate or biological nutrients than the wastewater.
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 tank.
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 tank.
4. The method of claim 1 , wherein wastewater is combined with the second portion of activated sludge in the off-line treatment tank.
5. The method of claim 1 , wherein controlling the off-line treatment tank 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
iii. mixing without aeration to achieve anaerobic conditions.
6. The method of claim 1 , wherein controlling the off-line treatment tank 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 tank 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 tank 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 tank 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. The method of claim 1 , wherein the second-biological population profile includes a lower proportion of filamentous biology than the first-biological population profile.
11. The method of claim 1 , wherein controlling the off-line treatment tank involves maintaining a target specific nitrogen uptake rate range or a target specific oxygen uptake rate range.
12. The method of claim 1 , wherein the off-line treatment tank is controlled to produce the second biological population in a first mode of operation, and further comprising controlling the off-line treatment tank to minimize a disposal volume of residual solids produced by the treatment of the wastewater in a second mode of operation.
13. The method of claim 12 , wherein a proportional frequency of operating in the first mode and the second mode is determined based on an amount of non-degradable content in the wastewater to be treated.
14. The method of claim 1 , wherein the second-biological population profile is customized using a sequencing of growth conditions including controlled mixing, air exposure, residence time and settling sequences.
15. The method of claim 1 , further comprising maintaining a suspended solids concentration in the off-line treatment tank at a level of below 10,000 mg/liter.
16. The method of claim 1 , wherein the step of returning at least a fraction of the produced second biological population to the treatment vessel comprises returning a fraction of the produced second biological population to the treatment vessel and includes decanting a portion of the produced second biological population from the off-line treatment tank.
17. The method of claim 16 , further comprising replacing the decanted portion with wastewater.
18. The method of claim 16 , wherein decanting from the off-line treatment tank is performed until a suspended solids content in the off-line treatment tank reaches a threshold level.
19. The method of claim 18 , further comprising directing contents of the off-line treatment tank at the threshold level to the treatment vessel or to disposal.
20. The method of claim 19 , further comprising adding activated sludge to the off-line treatment tank.
21. The method of claim 1 , further comprising maintaining a suspended solids concentration in the off-line treatment tank at a level of below 8,000 mg/liter.
22. 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 tank;
controlling the off-line treatment tank 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 contents of the off-line treatment tank to a condition selected from an aerobic condition, an anoxic condition and an anaerobic condition followed by subjecting the contents of the off-line treatment tank to a different condition selected from the aerobic condition, the anoxic condition and the anaerobic condition; and
returning at least a portion of the second biological population to the treatment vessel,
wherein the returned portion of the second biological population contains a higher level of soluble cBOD, nitrate or biological nutrients than the wastewater.
23. The method of claim 22 , 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 tank.
24. The method of claim 22 , 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 tank.
25. The method of claim 22 , wherein wastewater is combined with the drawn-off portion of the first biological population in the off-line treatment tank.
26. The method of claim 22 , wherein controlling the off-line treatment tank 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
iii. mixing without aeration to achieve anaerobic conditions.
27. The method of claim 22 , wherein controlling the off-line treatment tank 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.
28. The method of claim 22 , wherein controlling the off-line treatment tank 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.
29. The method of claim 22 , wherein controlling the off-line treatment tank 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.
30. The method of claim 22 , wherein controlling the off-line treatment tank 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.
31. The method of claim 22 , wherein the second biological population includes a lower proportion of filamentous biology than the first biological population.
32. The method of claim 22 , wherein controlling the off-line treatment tank comprises controlling an ORP level of the off-line treatment tank.
33. The method of claim 32 , wherein controlling an ORP level of the off-line treatment tank comprises a step of aerating until the ORP level is greater than 100 mV.
34. The method of claim 32 , wherein controlling an ORP level of the off-line treatment tank comprises a step of aerating until the ORP level is greater than 150 mV.
35. The method of claim 32 , wherein controlling an ORP level of the off-line treatment tank comprises a step of aerating until the ORP level is greater than 200 mV.
36. The method of claim 22 , further comprising maintaining a suspended solids concentration in the off-line treatment tank at a level of below 10,000 mg/liter.
37. 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 tank;
controlling the off-line treatment tank so as to produce, in the off-line treatment tank, 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, wherein said controlling step comprises subjecting the contents of the off-line treatment tank to a selected sequence of at least two conditions selected from the group consisting of an aerobic condition, an anoxic condition and an anaerobic condition, wherein the contents of the off-line treatment tank are maintained at each condition in the sequence for a corresponding determined length of time; and
returning at least a fraction of the produced second biological population to the treatment vessel,
wherein the returned fraction of the produced second biological population contains a higher level of soluble cBOD, nitrate or biological nutrients than the wastewater.
38. The method of claim 37 , 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 tank.
39. The method of claim 37 , 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 tank.
40. The method of claim 37 , wherein wastewater is combined with the second portion of separated sludge in the off-line treatment tank.
41. The method of claim 37 , wherein controlling the off-line treatment tank 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
iii. mixing without aeration to achieve anaerobic conditions.
42. The method of claim 37 , wherein controlling the off-line treatment tank 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.
43. The method of claim 37 , wherein controlling the off-line treatment tank 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.
44. The method of claim 37 , wherein controlling the off-line treatment tank 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.
45. The method of claim 37 , wherein controlling the off-line treatment tank 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.
46. The method of claim 37 , wherein the second biological population includes a lower proportion of filamentous biology than the first biological population.
47. The method of claim 37 , wherein the second-biological population profile includes a higher proportion of facultative aerobes, facultative anaerobes or nitrifiers than the first-biological population profile.
48. The method of claim 37 , further comprising maintaining a suspended solids concentration in the off-line treatment tank at a level of below 10,000 mg/liter.
49. The method of claim 48 , wherein the suspended solids concentration in the off-line treatment tank is maintained at a level of below 8,000 mg/liter.