Water filtration using immersed membranes

• US 20070051679A1
• Filed: 08/24/2006
• Published: 03/08/2007
• Est. Priority Date: 02/27/2004
• Status: Abandoned Application

• Current Assignee: Zenon Technology Partnership
• Original Assignee: Zenon Technology Partnership
• Inventors: Singh, Manwinder, Cote, Pierre, Ross, David, Adams, Nicholas, Kent, Fraser, Dufresne, Kevin
• Application Number:
  US11/508,983
• Publication Number:
  US 20070051679A1
• Time in Patent Office: Days
• US Class Current: 210/636
• CPC Class Codes: B01D 2315/06 Submerged-type; Immersion type
• CPC Class Codes: B01D 2315/08 Fully permeating type; Dead-end filtration
• CPC Class Codes: B01D 2321/04 Backflushing
• CPC Class Codes: B01D 2321/185 Aeration
• CPC Class Codes: B01D 61/18 Apparatus therefor
• CPC Class Codes: B01D 61/22 Controlling or regulating
• CPC Class Codes: B01D 65/02 Membrane cleaning or sterilisation ; Membrane regeneration
• CPC Class Codes: C02F 1/444 by ultrafiltration or microfiltration
• CPC Class Codes: C02F 3/1273 Submerged membrane bioreactors
• CPC Class Codes: Y02W 10/10 Biological treatment of water, waste water, or sewage

Abstract

A process and apparatus is described for filtering water with immersed membranes. In a batch process, permeate is withdrawn while the flow of feed is reduced or stopped at the end of a permeation cycle. The water level is reduced to a level where a portion of the membranes are exposed to air before draining the tank. In this or another process, the level of liquid is reduced to correspond with an area of the membrane fibers having an accumulation of solids. Aeration is provided for a period of time with the liquid at this level to dislodge at least a portion of the solids from the membranes. In these or other processes, the tank is partially drained between cycles to deconcentrate the tank, aeration is provided during backwashing and intermittently while permeating, and/or retentate is withdrawn from the tank during a portion of a permeation step.

Claims

1. A reactor having a membrane tank with a membrane module and an overflow area, the overflow area being fluidly connected to the tank through a valved passageway from the bottom of the overflow area to the tank such that the overflow area can drain into the tank, the passageway located below the top of the membrane module.

2. The reactor of claim 1 having a passageway between the tank and the overflow area, the overflow located above the passageway and above the top of the membrane module.

3. A filtration process using membranes immersed in a tank comprising the steps of:

a) permeating; and

,

b) after step (a), backwashing, aerating, partially draining the tank and refilling the tank,

wherein steps a) and b) are performed in repeated cycles.

4. The process of claim 3 wherein the step of permeating is dead end.

5. The process of claim 3 wherein 10-25% of the tank design volume or fill volume is drained in step b).

6. The process of claim 3 wherein the tank is partially drained to a level corresponding to an area of the membrane having an accumulation of solids and the membranes are aerated while the tank is held at that level.

7. A process according to claim 3 further comprising, after step (a) and before draining the tank, withdrawing permeate in excess of any feed water entering the tank.

8. The process of claim 3 further comprising providing aeration intermittently while permeating.

9. The process of claim 8 wherein aeration is provided while permeating for between 5 and 30 seconds every 1 to 5 minutes.

10. The process of claim 8 further comprising providing aeration while backwashing.

11. The process of claim 8 wherein step (b) occurs during step (a).

12. A filtration process comprising the steps of:

a) permeating;

b) after a), backpulsing;

c) during b) and extending into a portion of a), aerating; and

,

d) during a portion of a), withdrawing retentate,

wherein the steps above are performed in repeated cycles.

13. The process of claim 12 wherein part of step d) is performed during 25-60% of step (a).

14. The process of claim 12 wherein part of step d) is performed during step b).

15. The process of claim 12 further comprising reducing the water level to below a portion of the membranes during steps (a) or (d).

16. The process of claim 12 wherein less than the tank design or fill volume is drained in step (d).

17. The process of claim 12 wherein 10-25% of the tank design or fill volume is drained in step (d).

18. The process of claim 12 wherein the process is a non-recirculating process.

19. The process of claim 12 wherein the cycle time is between 15 minutes and 40 or 45 minutes.

20. The process of claim 19 wherein the cycle time is 30 minutes or less