Waste water treatment system with slip stream

• US 6,709,599 B1
• Filed: 04/26/2002
• Issued: 03/23/2004
• Est. Priority Date: 10/27/1999
• Status: Expired due to Term

• Current Assignee: Energysolutions LLC (Rockwell Holdco, Inc.)
• Original Assignee: RWE NUKEM Corporation (Rockwell Holdco, Inc.)
• Inventors: Wilson, James H, Underwood, Randall B., Whitehead, Howard, Raymount, John M Jr., Rosenberger, Stefan
• Primary Examiner(s): Cecil, Terry K.
• Application Number:
  US10/111,721
• Time in Patent Office: 697 Days
• Field of Search: 210/639, 210/665, 210/652, 210/641, 210/669, 210/702, 210/636, 210/605, 210/332, 210/805, 210/806, 210/206, 210/266, 210/258, 210/106, 210/196, 210/259, 210/321.69, 210/321.6, 210/195.2, 210/321.65, 210/650, 210/97, 210/912, 210/791, 376/313
• US Class Current: 210/652
• CPC Class Codes: B01D 2311/04 Specific process operations in the feed stream; Feed pretreatment
• CPC Class Codes: B01D 2311/16 Flow or flux control
• CPC Class Codes: B01D 2311/2649 Filtration
• CPC Class Codes: B01D 2321/04 Backflushing
• CPC Class Codes: B01D 2321/168 Use of other chemical agents
• CPC Class Codes: B01D 2321/185 Aeration
• CPC Class Codes: B01D 61/146 comprising multiple ultrafiltration steps
• CPC Class Codes: B01D 61/149 Multistep processes comprising different kinds of membrane processes selected from ultrafiltration or microfiltration
• CPC Class Codes: B01D 61/16 Feed pretreatment
• CPC Class Codes: B01D 65/02 Membrane cleaning or sterilisation ; Membrane regeneration
• CPC Class Codes: B01D 69/14 Dynamic membranes
• CPC Class Codes: C02F 1/001 Processes for the treatment of water whereby the filtration technique is of importance C02F1/44 takes precedence; construction of filters in general B01D24/00 - B01D41/00
• CPC Class Codes: C02F 1/44 by dialysis, osmosis or reverse osmosis general membrane separation processes B01D61/00, membrane modules B01D63/00, electrodialysis C02F1/4693, combination of membrane modules and bioreactors C02F3/1268
• CPC Class Codes: C02F 1/441 by reverse osmosis
• CPC Class Codes: C02F 1/442 by nanofiltration
• CPC Class Codes: C02F 1/444 by ultrafiltration or microfiltration
• CPC Class Codes: C02F 2303/16 Regeneration of sorbents, filters
• CPC Class Codes: G21C 19/48 Non-aqueous processes
• CPC Class Codes: G21F 9/04 Treating liquids
• CPC Class Codes: G21F 9/12 by absorption; by adsorption; by ion-exchange
• CPC Class Codes: G21F 9/125 : by solvent extraction
• CPC Class Codes: Y02E 30/30 : Nuclear fission reactors
• CPC Class Codes: Y02W 30/50 : Reuse, recycling or recovery technologies
• CPC Class Codes: Y10T 436/255 : including use of a solid sorbent, semipermeable membrane, or liquid extraction

Abstract

A method and apparatus for processing waste streams wherein a slipstream is formed on the upstream side of an ultrafiltration membrane (120) to carry collected and concentrated filter reject to a microfilter (170) via a slipstream through a conduit (155) at a very low flux through the microfilter. The low flux gives the particles in this stream a chance to interact and thus form an irregular matrix that itself helps to trap particles. The effluent from this matrix and microfilter is returned upstream of the ultrafiltration membrane via a conduit (165) to be repeatedly collected and concentrated. The suspended solids removed from the reject stream and microfilter may then be disposed of directly without further processing. For metal ions, the removal efficiency of ultrafiltration membrane can be improved by injecting sulfide compounds or other compounds upstream of ultrafiltration membrane. Water, a combination of air and water, or a combination of ozone and water can be used to back flush or to clean the ultrafiltration membrane. The water used for back flushing can be the filtrate from the ultrafiltration membrane.

Claims

1. A waste water treatment apparatus for use in line with a source of waste water, said system comprising:

a first filter having an upstream side and an opposing downstream side and a pore size, said upstream side being in fluid communication with said source of waste water and adapted so that said waste water passes through said first filter leaving a first filter reject flow on said upstream side, said first filter reject flow containing particulate;

slipstream means for creating and controlling a slipstream flow from said reject flow on said upstream side of said first filter; and

a second filter having a micron rating larger than said pore size of said first filter, said second filter primarily providing mechanical filtration, said second filter having an upstream side and an opposing downstream side, said second filter being connected to a conduit so that, when said slipstream means creates and controls said slipstream flow, said second filter receives on said upstream side thereof a controlled flow containing said first filter reject flow particulate, said second filter collecting a second filter reject on said upstream side thereof, said second filter having second filter filtrate flow on said downstream side thereof, said second filter filtrate flow being recycled to said upstream side of said first filter, wherein waste water flow from said source of waste water is directed first to said first filter prior to a portion of said waste water flow being directed to said second filter by said slipstream means, whereby, due to repeated recycling of said slipstream between said first filter and said second filter, about 100% of said waste water passes through said first filter and about 100% of said particulate is collected by said second filter as said second filter reject without the need to drain said slipstream containing said first filter reject.

2. The apparatus as recited in claim 1, wherein said first filter is an ultrafiltration membrane.

3. The apparatus as recited in claim 1, wherein said second filter is a microfilter.

4. The apparatus as recited in claim 1, wherein said downstream side of said first filter is in fluid communication with a means for removing dissolved contaminants.

5. The apparatus as recited in claim 1, wherein said downstream side of said first filter is in fluid communication with a reverse osmosis unit.

6. The apparatus as recited in claim 1, wherein said slipstream flow has a flux through said second filter that is maintained low enough so that said slipstream can just pass through said second filter.

7. The apparatus as recited in claim 1, further comprising means for precipitating metals in said waste water, said precipitating means located upstream of said first filter.

8. The apparatus as recited in claim 1, further comprising means for back flushing said first filter, said back flushing means located downstream of said first filter.

9. The apparatus as recited in claim 8, wherein said back flushing means further comprises a tank for holding a back flushing liquid, said back flushing liquid used for back flushing said first filter.

10. The apparatus as recited in claim 9, wherein said back flushing liquid is said first filter filtrate.

11. The apparatus as recited in claim 10, wherein said back flushing means removes particulate from said upstream side of said first filter, said particulate being directed to said slipstream and received by said second filter.

12. The apparatus as recited in claim 8, wherein said back flushing means uses said recycled slipstream to provide a high velocity flow across said upstream side of said first filter in order to increase back flushing flux recovery efficiency.

13. The apparatus as recited in claim 1, wherein said apparatus produces an effluent that does not require additional processing, said effluent being downstream of said downstream side of said first filter.

14. The apparatus as recited in claim 1, wherein said apparatus does not produce a liquid waste stream that requires additional processing.

15. The apparatus as recited in claim 1, wherein said second filter is a disposable cartridge-type filter carried in a housing.

16. The apparatus as recited in claim 1, wherein a flux of said slipstream flow through said second filter is maintained low enough so that a cake of particles is formed on said upstream side of said second filter.

17. The apparatus as recited in claim 16, wherein said slipstream flux through said second filter is maintained low enough so that said slipstream can just pass through said second filter without affecting said cake of particles.

18. The apparatus as recited in claim 1, wherein a portion of a recirculating reject stream bypasses sad second filter and is recycled to said upstream side of said first filter, said recirculating reject stream having a high enough velocity to carry said first filter reject away from said upstream side of said first filter, wherein a portion of said recirculating reject stream that does not bypass said second filter becomes said slipstream flow.

19. The apparatus as recited in claim 1, wherein said about 100% of said particulate is collected by said second filter without said second filter having a high per pass particulate removal efficiency.

20. The apparatus as recited in claim 1, wherein said waste water from said source of waste water contains radioactive materials.

21. The apparatus as recited in claim 1, wherein said water from said source of waste water contains hazardous materials.

22. The apparatus as recited in claim 1, wherein said waste water from said source of waste water contains radioactive materials and hazardous materials.

23. The apparatus as recited in claim 1, wherein said second filter reject can be further processed to recover useful materials contained within said second filter reject.

24. The apparatus as recited in claim 23, wherein said useful materials are precious metals.

25. The apparatus as recited in claim 23, wherein said useful materials are biologically based materials, said biologically based materials being recovered without the need for thermal processing.

26. The apparatus as recited in claim 1, wherein said particulate is collected without the need for thermal processing.

27. The apparatus as recited in claim 1, wherein said second filter reject can be disposed without the need for thermal processing.

28. The apparatus as recited in claim 1, wherein said first filter primarily provides mechanical filtration.

29. An apparatus for use with a waste treatment system having a source of waste water carrying particulate and an ultrafiltration membrane downstream of and in fluid communication with said waste water source, said ultrafiltration membrane having an upstream side and a downstream side, said apparatus comprising:

means for establishing a recirculating reject stream on said upstream side of said ultrafiltration membrane so that particles rejected by said ultrafiltration membrane can be carried away from said upstream side of said ultrafiltration membrane;

means for establishing a slipstream from said recirculating reject stream so that particles rejected by said ultrafiltration membrane and carried by said recirculating reject stream can be removed from said recirculating reject stream;

a microfilter in fluid communication with said slipstream establishing means and receiving said slipstream to remove said particles rejected by said ultrafiltration membrane and carried by said recirculating reject stream, wherein waste water flow from said source of waste water is directed first to said ultrafiltration membrane prior to a portion of said waste water flow being directed to said recirculating reject stream and to said microfilter by said slipstream establishing means; and

means for controlling the flux of said slipstream through said microfilter.

30. The apparatus as recited in claim 29, further comprising means for recycling filtrate from said microfilter to said upstream side of said ultrafiltration membrane.

31. The apparatus as recited in claim 29, further comprising means for back flushing said ultrafiltration membrane, said back flushing means being in fluid communication with said downstream side of said ultrafiltration membrane.

32. The apparatus as recited in claim 31, wherein said back flushing means further comprise a tank for holding a back flushing liquid, said back flushing liquid used for back flushing said ultrafiltration membrane.

33. The apparatus as recited in claim 31, wherein said back flushing means uses said recirculating reject stream to provide a high velocity flow across said upstream side of said ultrafiltration membrane in order to increase a back flushing flux recovery efficiency.

34. The apparatus as recited in claim 29, further comprising means for precipitating dissolved metals in said waste water, said precipitating means being located on said upstream side of said ultrafiltration membrane.

35. A method for processing waste water, said method comprising the steps of:

directing a flow of wastewater toward a first filter having a first pore size so that said first filter divides said waste water into a filtrate on a downstream side of said first filter and a first filter reject flow on an upstream side of said first filter, said first filter reject flow containing suspended solids;

allowing a slipstream to be formed on said upstream side of said first filter to carry a portion of said first filter reject flow;

directing said slipstream toward a second filter having a micron rating larger than said first pore size of said first filter wherein said flow of waste water is directed to said first filter prior to a portion of said flow of waste water being directed to said second filter by said slipstream; and

recycling said slipstream between said first filter and said second filter repeatedly so that about 100% of said waste water passes through said first filter and about 100% of said particulate is collected by said second filter as said second filter reject without the need to drain said slipstream containing said first filter reject.

36. The method as recited in claim 35, further comprising the step of maintaining the flux of said slipstream across said second filter low enough to permit removal of at least a portion of said first filter reject in said slipstream with each pass.

37. The method as recited in claim 36, further comprising the step of forming a cake of particles on an upstream side of said second filter.

38. The method as recited in claim 37, further comprising the step of dewatering said cake of particles.

39. The method as recited in claim 35, wherein said first filter is an ultrafiltration membrane.

40. The method as recited in claim 35, wherein said second filter is a microfilter.

41. The method as recited in claim 35, further comprising the step of disposing of said second filter reject without requiring additional processing of said second filter reject.

42. The method as recited in claim 35, further comprising the step of injecting sulfides or other chemicals into said waste stream on said upstream side of said first filter.

43. The method as recited in claim 35, further comprising the step of back flushing said first filter with a mixture of ozone and water.

44. The method as recited in claim 35, further comprising the step of recovering useful materials contained within said second filter reject.

45. The method as recited in claim 44, wherein said useful materials are precious metals.

46. The method as recited in claim 44, wherein said useful materials are biologically based materials, said biologically based materials being recovered without the need for thermal processing.