Grease and scum removal in a filtration apparatus comprising a membrane bioreactor and a treatment vessel for digesting organic materials

• US 20070084791A1
• Filed: 12/21/2005
• Published: 04/19/2007
• Est. Priority Date: 12/22/2004
• Status: Active Grant

• Current Assignee: Evoqua Water Technologies LLC (Xylem, Inc.)
• Original Assignee: Siemens Water Technologies Corp (Siemens AG)
• Inventors: Jordan, Edward, Elefritz, Robert
• Granted Patent: US 7,329,344 B2
• Time in Patent Office: Days
• US Class Current: 210/608
• CPC Class Codes: B01D 2315/06 Submerged-type; Immersion type
• CPC Class Codes: B01D 2315/12 Feed-and-bleed systems
• CPC Class Codes: B01D 2321/2033 dynamically
• CPC Class Codes: B01D 61/145 Ultrafiltration
• CPC Class Codes: B01D 61/18 Apparatus therefor
• CPC Class Codes: B01D 65/08 Prevention of membrane fouling or of concentration polarisation
• CPC Class Codes: C02F 3/1268 Membrane bioreactor systems
• CPC Class Codes: Y02W 10/10 Biological treatment of water, waste water, or sewage

Abstract

The invention relates to a membrane bioreactor process combined with an advanced biological sludge digestion process that provides significant improvements in sludge digestion by reducing the costs and resources required for disposing of digested sludge. The offline treatment vessel is used to solubilize the organic material by operating in a very low oxygen environment. Digested process fluid is transferred back to the membrane bioreactor. The processes and apparatus substantially reduce the production of waste sludge. The device includes one or more weirs operable to remove grease and scum.

Claims

1. A membrane bioreactor for wastewater purification comprising:

a biological purification system;

an immersed membrane purification system;

a downstream channel for fluid flow from the biological purification system to the membrane purification system;

a return channel for fluid flow from the membrane purification system to the biological purification system;

an overflow weir on the downstream channel to remove overflow and floating impurities from the downstream channel.

2. A membrane bioreactor according to claim 1 further including a second return channel to remove floating impurities from the membrane purification system for return to the biological purification system.

3. A membrane bioreactor according to claim 1 further including a take-off channel to remove floating impurities from the membrane purification system for disposal.

4. A membrane bioreactor according to claim 1 wherein the weir is located within the biological purification system.

5. A membrane bioreactor according to claim 1 wherein the weir is located within the membrane purification system.

6. A membrane bioreactor according to claim 1 wherein the weir is located between within the biological purification system and membrane purification system.

7. A membrane bioreactor according to claim 1 wherein the weir is located external to the biological purification system and membrane purification system.

22. A membrane bioreactor according to claim 1 comprising a tank containing the immersed membranes.

23. A membrane bioreactor according to claim 22 wherein the immersed membranes are a plurality of hollow fibre membranes, bundled into vertically arrayed membrane modules.

24. A membrane bioreactor according to claim 23 comprising a mixed liquor feed channel from the biological purification system which enters the membrane modules at the base.

25. A membrane bioreactor according to claim 22 including a frit at the base of the membrane modules to introduce air bubbles to scour and fluidise solid contaminants that may be present on the outer surface of the membrane.

26. A membrane bioreactor according to claim 22 wherein flow in the return channel from the membrane filtration unit is fed by the fluid from the immersed membranes.

27. A membrane bioreactor according to claim 26 wherein the return channel is positioned at a height above the height of the immersed membrane.

8. A membrane bioreactor for wastewater purification comprising:

a biological purification system;

an immersed membrane purification system;

a downstream channel for fluid flow from the biological purification system to the membrane purification system; and

an overflow weir on the downstream channel to remove overflow and floating impurities from the downstream channel.

9. A membrane bioreactor according to claim 8 further including a second return channel to remove floating impurities from the membrane purification system for return to the biological purification system.

10. A membrane bioreactor according to claim 8 further including a take-off channel to remove floating impurities from the membrane purification system for disposal.

11. A membrane bioreactor according to claim 8 wherein the weir is located within the biological purification system.

12. A membrane bioreactor according to claim 8 wherein the weir is located within the membrane purification system.

13. A membrane bioreactor according to claim 8 wherein the weir is located between within the biological purification system and membrane purification system.

14. A membrane bioreactor according to claim 8 wherein the weir is located external to the biological purification system and membrane purification system.

15. A membrane bioreactor for wastewater purification comprising:

a biological purification system;

an immersed membrane purification system;

a return channel for fluid flow from the membrane purification system to the biological purification system;

an overflow weir on the return channel to remove overflow and floating impurities from the membrane purification system.

16. A membrane bioreactor according to claim 15 further including a second return channel to remove floating impurities from the membrane purification system for return to the biological purification system.

17. A membrane bioreactor according to claim 15 further including a take-off channel to remove floating impurities from the membrane purification system for disposal.

18. A membrane bioreactor according to claim 15 wherein the weir is located within the biological purification system.

19. A membrane bioreactor according to claim 15 wherein the weir is located within the membrane purification system.

20. A membrane bioreactor according to claim 15 wherein the weir is located between within the biological purification system and membrane purification system.

21. A membrane bioreactor according to claim 15 wherein the weir is located external to the biological purification system and membrane purification system.

28. A method of removing floating contaminants from waste stream in comprising providing a feed stream to a biological purification system, obtaining an exit stream from the biological purification system which contains a first flotsam, removing the first flotsam to provide a stripped exit steam, feeding the stripped exit stream to an immersed membrane filtration unit in a tank, and further removing second flotsam from the tank.

29. A method according to claim 28 wherein the first flotsam is removed by overflowing the exit stream over a weir.

30. A method according to claim 28 wherein the first flotsam is scum.

31. A method according to claim 30 wherein the scum is aerated oils or greases.

32. A method according to claim 30 wherein the scum is removed into a scum disposal unit for disposal.

33. A method according to claim 30 wherein the scum is removed into a scum disposal unit for further treatment.

34. A method according to claim 33 wherein the further treatment is settling.

35. A method according to claim 28 wherein the second flotsam is removed by overflowing the feed into the immersed membrane filtration unit tank.

36. A method according to claim 28 wherein the second flotsam is fed into a scum disposal unit.

37. A method according to claim 28 wherein the second flotsam is returned as feed into the biological purification system.

38. A method according to claim, 37 wherein the flow in the downstream channel is regulated to allow overflow, causing any floating materials such as scum, grease or oil to spill over into a scum collection system.

39. A method according to claim 38 wherein the flow in the downstream channel is regulated by controlling inflow.

40. A method according to claim 39 wherein the flow in the downstream channel is regulated by controlling outflow.

41. A method according to claim 38 wherein the scum grease or oil is removed.

42. A method according to claim 38 wherein the scum grease or oil is returned to the bioreactor.

43. A method according to claim 38 wherein the membrane component is a tank containing immersed membranes which are a plurality of hollow fibre membranes bundled into vertically arrayed modules.

44. A method according to claim 43 wherein mixed liquor feed from the biological purification system enters the membrane modules contacting the outer surface of the hollow fibre membranes and wherein clean water collects in the lumens of the hollow fibres and is drawn off for use.

45. A method according to claim 44 wherein the mixed liquor feed enters the membrane module at the base thereof.

46. A method according to claim 45 wherein the membrane component is of the type where air bubbles are introduced at the base of the membrane modules, thereby to scour and fluidise solid contaminants, where present, on the outer surface of the membrane.

47. A method according to claim 46 wherein the flow in the return channel from the membrane filtration unit is fed by the fluid from the immersed membranes.

48. A method according to claim 47 wherein the return channel is positioned at a height above the height of the immersed membrane.

49. A method according to claim 48 wherein the return channel is operative by increasing the fluid height in the tank.

50. A method according to claim 49 wherein the fluid height in the tank is increased by increasing the flow from the biological purification system.

51. A method according to claim 49 wherein the fluid height in the tank is increased by decreasing the flow from the membrane purification system.

52. A method according to claim 49 wherein the fluid height in the tank is increased by increasing the flow from the biological purification system and increased by decreasing the flow from the membrane purification system.

53. A method according to claim 49 wherein the fluid height is increased by changing the volume of the membrane purification system or adding additional fluids.

54. A method according to claim 28 wherein flow along the return channel is discarded.

55. A method according to claim 28 wherein flow along the return channel is returned in part or in full to the biological purification system.

56. A method according to claim 55 wherein flow returned in part or full is returned by directing a lower portion of the flow to the bioreactor, with the scum and oils being discarded at that point.

57. A method according to claim 55 wherein flow returned in part or full is returned to the anoxic zone of the biological purification system.