Biological method of phosphorus removal and biological phosphorus-removing apparatus

• US 6,706,185 B2
• Filed: 05/22/2002
• Issued: 03/16/2004
• Est. Priority Date: 05/22/2002
• Status: Expired due to Fees

• Current Assignee: Kurita Water Industries Limited
• Original Assignee: Kurita Water Industries Limited
• Inventors: Goel, Rajeev, Yasui, Hidenari
• Primary Examiner(s): Prince, Fred G.
• Application Number:
  US10/151,962
• Publication Number:
  US 20030217968A1
• Time in Patent Office: 664 Days
• Field of Search: 210/605, 210/623, 210/624, 210/626, 210/630, 210/195.1, 210/195.2, 210/195.3, 210/252, 210/259, 210/906
• US Class Current: 210/605
• CPC Class Codes: C02F 1/78 with ozone C02F1/4672 takes precedence
• CPC Class Codes: C02F 3/1221 comprising treatment of the recirculated sludge
• 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 210/906 Phosphorus containing

Abstract

An apparatus and method for the biological removal of phosphorus, in which raw water is introduced into the anaerobic tank 11, together with returned sludge from the sludge return pipe 14. Some of the water in the anaerobic tank 11 is sent to the solid/liquid separating device 16 and the rest is sent to the aerobic tank 12. Some of the water which contains the released phosphorus in the anaerobic tank 11 is sent via the pipe 15 to the second solid/liquid separating device 16, and subjected to a solid/liquid separation treatment. The separated water fraction is sent to the phosphorus-removing apparatus 17 and the phosphorus is removed. Some of the solid fraction is introduced into the anaerobic tank 11. The remainder is sent from the pipe 19 to the solubilizing tank 20 and subjected to a solubilizing treatment, and then it is returned to the anaerobic tank 11.

Claims

1. A biological method of removing phosphorus from raw water, comprising:

releasing phosphorus from activated sludge in a first anaerobic tank in a phosphorus-releasing step,

absorbing the phosphorus with activated sludge in a mixed liquor of the raw water and the activated sludge in an aerobic tank in a phosphorus-absorbing step,

separating sludge from the mixed liquor in a first solid/liquid separation step,

supplying the sludge which has been concentrated and separated from the mixed liquor in the first solid/liquid separation step to a second anaerobic tank in a second phosphorus-releasing step,

subjecting the sludge from the second phosphorus-releasing step to a second solid/liquid separation step,

solubilizing sludge which has been concentrated and separated in the second solid/liquid separation step in a solubilizing step,

supplying at least some of the sludge which has been solubilized in the solubilizing step to the first anaerobic tank,

supplying at least some of the sludge which has been solubilized in the solubilizing step to the second anaerobic tank, and

removing phosphorus from liquid which has been separated in the second solid/liquid separation step.

2. The method of claim 1, wherein some of the sludge separated in the second solid/liquid separation step by-passes the solubilizing step and is supplied to the first anaerobic tank.

3. The method of claim 1, wherein the solubilized sludge is fermented in a fermentation treatment process prior to being supplied to the first anaerobic tank.

4. The method of claim 2, wherein the solubilized sludge is fermented in a fermentation treatment process prior to being supplied to the first anaerobic tank.

5. An apparatus for the biological removal of phosphorus from raw water, the apparatus comprises:

a first anaerobic tank into which the raw water and activated sludge are introduced to form a mixed liquor,

an aerobic tank in which the mixed liquor from the first anaerobic tank is aerated,

a settling tank in which the mixed liquor flowing out of said aerobic tank is subjected to solid/liquid separation,

a first pipe connecting the settling tank to the first anaerobic tank whereby some of the sludge separated from the mixed liquor in the settling tank is returned as the activated sludge to the first anaerobic tank,

a second anaerobic tank in which a remaining portion of the separated sludge from the settling tank is maintained anaerobically and phosphorus is released from the sludge,

a solid/liquid separating device in which sludge admixed liquid from the second anaerobic tank is subjected to solid/liquid separation,

a solubilizing device in which sludge separated in said solid/liquid separating device is solubilized,

a solubilized sludge returning device with which sludge which has been solubilized in said solubilizing device is returned to the first anaerobic tank,

a second pipe for supplying some of the sludge which has been solubilized in the solubilizing device to the second anaerobic tank, and

a phosphorus-removing device in which phosphorus is removed from water which has been separated in the solid/liquid separating device.

6. The apparatus of claim 5, further comprising a fermentation tank, into which the sludge which has been solubilized in the solubilizing device is introduced and subjected to a fermentation treatment, and the sludge which has been subjected to the fermentation treatment in said fermentation tank is returned to the first anaerobic tank.

7. The apparatus of claim 6, further comprising means for supplying some of the sludge which has been subjected to the fermentation treatment in the fermentation tank to the second anaerobic tank.

8. The apparatus of claim 7, further comprising means for supplying at least some of the sludge separated in said solid/liquid separating device directly to the first anaerobic tank.

9. An apparatus for the biological removal of phosphorus from raw water, the apparatus comprises:

a first anaerobic tank into which the raw water and activated sludge are introduced to form a mixed liquor,

an aerobic tank in which the mixed liquor from the first anaerobic tank is aerated,

first solid/liquid separating means for solid/liquid separation of the mixed liquor flowing out of said aerobic tank,

means for returning some of the sludge separated from the mixed liquor in the first solid/liquid separating means is returned as the activated sludge to the first anaerobic tank,

a second anaerobic tank in which a remaining portion of the separated sludge from the settling tank is maintained anaerobically and phosphorus is released from the sludge,

second solid/liquid separating means for solid/liquid separation of the sludge admixed liquid from the second anaerobic tank,

means for solubilizing sludge separated in said second solid/liquid separating means,

solubilized sludge returning means for returning at least some of the sludge which has been solubilized in said solubilizing means to the first anaerobic tank,

means for supplying at least some of the sludge which has been solubilized in the solubilizing means to the second anaerobic tank, and

means for removing phosphorus from liquid which has been separated in the second solid/liquid separating means.

10. The apparatus of claim 9, further comprising:

a fermentation tank, into which the sludge which has been solubilized in the solubilizing means is introduced and subjected to a fermentation treatment, and

means for returning the sludge which has been subjected to the fermentation treatment in said fermentation tank to the first anaerobic tank.

11. The apparatus of claim 10, further comprising means for supplying some of the sludge which has been subjected to the fermentation treatment in the fermentation tank to the second anaerobic tank.

12. The apparatus of claim 11, further comprising means for supplying at least some of the sludge separated in said second solid/liquid separating means directly to the first anaerobic tank.

13. An apparatus for the biological removal of phosphorus from raw water, the apparatus comprises:

a first anaerobic tank into which the raw water and activated sludge are introduced to form a mixed liquor,

an anoxic tank in which bound oxygen is applied to the mixed liquor from said first anaerobic tank,

an aerobic tank in which the mixed liquor from said oxygen-free tank is aerated.

a first pipe which returns some of the mixed liquor from said aerobic tank to the oxygen-free tank,

a settling tank in which the mixed liquor flowing out of said aerobic tank is subjected to solid/liquid separation,

a second pipe whereby some of the solid/liquid separated sludge from the settling tank is returned as the activated sludge to the first anaerobic tank,

a second anaerobic tank in which a remaining portion of the separated sludge from the settling tank is maintained anaerobically and the phosphorus is released,

a solid/liquid separating device in which the sludge admixed liquid from said second anaerobic tank is subjected to solid/liquid separation,

a solubilizing device in which the sludge separated in said solid/liquid separating device is solubilized,

a solubilized sludge returning device in which sludge which has been solubilized in said solubilizing device is returned to the first anaerobic tank,

a third pipe for supplying some of the sludge which has been solubilized in the solubilizing device to said second anaerobic tank, and

a phosphorus-removing device in which phosphorus is removed from water which has been separated in the solid/liquid separating device.

14. The apparatus of claim 13, further comprising a fermentation tank, into which the sludge which has been solubilized in the solubilizing device is introduced and subjected to a fermentation treatment, and the sludge which has been subjected to the fermentation treatment in said fermentation tank is returned to the first anaerobic tank.

15. The apparatus of claim 14, further comprising means for supplying some of the sludge which has been subjected to the fermentation treatment in the fermentation tank to the second anaerobic tank.

16. The apparatus of claim 15, further comprising means for supplying at least some of the sludge separated in said solid/liquid separating device directly to the first anaerobic tank.

17. An apparatus for the biological removal of phosphorus from raw water, the apparatus comprising:

a first anaerobic tank into which the raw water and activated sludge are introduced to form a mixed liquor,

an anoxic tank in which bound oxygen is applied to the mixed liquor from said first anaerobic tank,

an aerobic tank in which the mixed liquor from said oxygen-free tank is aerated,

mixed liquor returning means which returns some of the mixed liquor from said aerobic tank to the oxygen-free tank,

first solid/liquid separating means in which the mixed liquor flowing out of said aerobic tank is subjected to solid/liquid separation,

means whereby some of the solid/liquid separated sludge from said first solid/liquid separating means is returned as the activated sludge to the first anaerobic tank,

a second anaerobic tank in which the remaining solid/liquid separated sludge from the first solid/liquid separating means is maintained anaerobically and the phosphorus is released,

second solid/liquid separating means in which the sludge admixed liquid from said second anaerobic tank is subjected to solid/liquid separation,

solubilizing means in which the sludge separated in said second solid/liquid separating means is solubilized,

solubilized sludge returning means with which at least some of the sludge which has been solubilized in said solubilizing means is returned to the first anaerobic tank,

means for supplying at least some of the sludge which has been solubilized in the solubilizing means to said second anaerobic tank, and

phosphorus-removing means for removing phosphorus from water which has been separated in the second solid/liquid separating means.

18. The apparatus of claim 17, further comprising a fermentation tank, into which the sludge which has been solubilized in the solubilizing means is introduced and subjected to a fermentation treatment, and the sludge which has been subjected to the fermentation treatment in said fermentation tank is returned to the first anaerobic tank.

19. The apparatus of claim 18, further comprising means for supplying some of the sludge which has been subjected to the fermentation treatment in the fermentation tank to the second anaerobic tank.

20. The apparatus of claim 19, further comprising means for supplying at least some of the sludge separated in said second solid/liquid separating means directly to the first anaerobic tank.

21. An apparatus for the biological removal of phosphorus from raw water, the apparatus comprises:

an anaerobic tank into which the raw water and activated sludge are introduced to form a mixed liquor,

an aerobic tank in which the mixed liquor from said anaerobic tank is aerated,

first solid/liquid separating means in which the mixed liquor flowing out of said aerobic tank is subjected to solid/liquid separation,

means for returning at least some of the solid/liquid separated sludge from said first solid/liquid separating means as the activated sludge to the anaerobic tank,

second solid/liquid separating means in which some of the mixed liquor discharged from the anaerobic tank is subjected to solid/liquid separation,

solubilizing means for solubilizing at least some of the sludge separated in said second solid/liquid separating means,

solubilized sludge returning means with which sludge which has been solubilized in said solubilizing means is returned to the anaerobic tank, and

phosphorus-removing means with which phosphorus is removed from water which has been separated in the second solid/liquid separating means.

22. The apparatus of claim 21, further comprising means whereby the water, from which the phosphorus has been removed in the phosphorus-removing means, is subjected to an aerobic treatment or whereby said water is supplied to the oxygen-free tank or the aerobic tank.

23. The apparatus of claim 21, wherein the solubilized sludge returning means supplies some of the sludge which has been separated by the second solid/liquid separating means to the solubilizing means, and further comprising means which supplies a remainder of the sludge which has been separated by said second solid/liquid separating means to the anaerobic tank or the aerobic tank.

24. An apparatus for the biological removal of phosphorus from raw water, the apparatus comprises:

an anaerobic tank into which the raw water and activated sludge are introduced to form a mixed liquor,

an oxygen-free tank in which bound oxygen is applied to the mixed liquor from said anaerobic tank,

an aerobic tank in which the mixed liquor from said oxygen-free tank is aerated,

first solid/liquid separating means in which the mixed liquor flowing out of said aerobic tank is subjected to solid/liquid separation,

means for returning at least some of the solid/liquid separated sludge from said first solid/liquid separating means as the activated sludge to the anaerobic tank,

second solid/liquid separating means in which some of the mixed liquor discharged from the anaerobic tank is subjected to solid/liquid separation,

solubilizing means in which at least some of the sludge separated in said second solid/liquid separating means is solubilized,

solubilized sludge returning means with which at least some of the sludge which has been solubilized in said solubilizing means is returned to the anaerobic tank, and

phosphorus-removing means with which phosphorus is removed from water which has been separated in the second solid/liquid separating means.

25. The apparatus of claim 24, further comprising means whereby the water, from which the phosphorus has been removed in the phosphorus-removing means, is subjected to an aerobic treatment or whereby said water is supplied to the oxygen-free tank or the aerobic tank.

26. The apparatus of claim 24, wherein the solubilized sludge returning means supplies some of the sludge which has been separated by the second solid/liquid separating means to the solubilizing means, and further comprising means which supplies a remainder of the sludge which has been separated by said second solid/liquid separating means to the anaerobic tank or the aerobic tank.

27. The apparatus of claim 24, further comprising a fermentation tank, into which at least some of the sludge which has been solubilized in the solubilizing means is introduced and subjected to a fermentation treatment, and the sludge which has been subjected to the fermentation treatment in said fermentation tank is returned to the anaerobic tank.

28. The apparatus of claim 27, wherein the solubilized sludge returning means supplies only some of the sludge which has been solubilized in the solubilizing means to the fermentation tank, and there is provided a means by which a remainder of the sludge which has been solubilized in said solubilizing means is supplied to the second solid/liquid separating means.

29. The apparatus of claim 28, further comprising means for supplying some of the sludge which has been subjected to a fermentation treatment in the fermentation tank to the second solid/liquid separating means.

30. The apparatus of claim 29, further comprising means whereby some of the raw water is supplied to the fermentation tank.

31. An apparatus for the biological removal of phosphorus from raw water, the apparatus comprises:

an anaerobic tank into which the raw water and activated sludge are introduced to form a mixed liquor,

an aerobic tank in which the mixed liquor from said anaerobic tank is aerated,

first solid/liquid separating means in which the mixed liquor flowing out of said aerobic tank is subjected to solid/liquid separation,

means for returning at least some of the sludge separated from the mixed liquor in said first solid/liquid separating means as the activated sludge to the anaerobic tank,

second solid/liquid separating means in which some of the mixed liquor discharged from the anaerobic tank is subjected to solid/liquid separation,

solubilizing means for solubilizing at least some of the sludge separated in said second solid/liquid separating means,

solubilized sludge returning means with which sludge which has been solubilized in said solubilizing means is returned to the anaerobic tank,

means for returning at least some of the sludge separated in said second solid/liquid separating means to at least one of the anaerobic tank and the aerobic tank, and

phosphorus-removing means with which phosphorus is removed from water which has been separated in the second solid/liquid separating means.

32. The apparatus of claim 31, wherein at least some of the sludge separated in said second solid/liquid separating means is returned to both the anaerobic tank and the aerobic rank.

33. An apparatus for the biological removal of phosphorus from raw water, the apparatus comprises:

an anaerobic tank into which the raw water and activated sludge are introduced to form a mixed liquor,

an aerobic tank in which the mixed liquor from said anaerobic tank is aerated,

first solid/liquid separating means in which the mixed liquor flowing out of said aerobic tank is subjected to solid/liquid separation,

means for returning at least some of the solid/liquid separated sludge from said first solid/liquid separating means as the activated sludge to the anaerobic tank,

second solid/liquid separating means in which some of the mixed liquor discharged from the anaerobic tank is subjected to solid/liquid separation,

means for returning at least some of the solid/liquid separated sludge from said second solid/liquid separating means to at least one of the anaerobic tank and the aerobic tank,

solubilizing means for solubilizing at least some of the sludge separated in the second solid/liquid separating means,

a fermentation tank, into which at least some of the sludge which has been solubilized is introduced and subjected to a fermentation treatment,

means for supplying solubilized sludge to the fermentation tank,

means for returning at least some of the sludge subjected to the fermentation treatment to the anaerobic tank, and

phosphorus-removing means with which phosphorus is removed from water which has been separated in the second solid/liquid separating means.

34. The apparatus of claim 33, wherein at least some of the sludge separated in said second solid/liquid separating means is returned to both the anaerobic tank and the aerobic tank.

35. The apparatus of claim 33, further comprising means for returning at least some of the solubilized sludge to the second solid/liquid separating means.

36. The apparatus of claim 33, further comprising a means for supplying at least some of the sludge subjected to the fermentation treatment to the second solid/liquid separating means.

37. The apparatus of claim 33, further comprising means for supplying raw water to the fermentation tank.