Simple gas scouring method and apparatus

• US 8,758,622 B2
• Filed: 12/22/2005
• Issued: 06/24/2014
• Est. Priority Date: 12/24/2004
• Status: Expired due to Fees

• Current Assignee: Siemens Water Technologies LLC (Evoqua Water Technologies LLC)
• Original Assignee: Evoqua Water Technologies LLC
• Inventors: Muller, Joachim
• Primary Examiner(s): Jarrett, Lore
• Assistant Examiner(s): Behrendt, Benjamin J
• Application Number:
  US11/722,458
• Publication Number:
  US 20100000941A1
• Time in Patent Office: 3,106 Days
• Field of Search: 210/636
• US Class Current: 210/636
• CPC Class Codes: B01D 2313/26 Specific gas distributors or gas intakes
• CPC Class Codes: B01D 2315/08 Fully permeating type; Dead-end filtration
• CPC Class Codes: B01D 2321/16 Use of chemical agents
• CPC Class Codes: B01D 2321/185 Aeration
• CPC Class Codes: B01D 61/20 Accessories; Auxiliary operations
• CPC Class Codes: B01D 65/02 Membrane cleaning or sterilisation ; Membrane regeneration
• 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 2301/063 Underpressure, vacuum
• CPC Class Codes: C02F 2303/16 Regeneration of sorbents, filters

Abstract

A method of cleaning a membrane (6) in a membrane filtration system by flowing gas bubbles past the surfaces of the membrane (6) to scour accumulated solids therefrom. The method includes flowing a liquid past a supply of gas; creating a reduced pressure within the liquid flow to cause a flow of gas from the supply of gas (9) into the liquid flow and form gas bubbles therein and then flowing the liquid containing the gas bubbles past the surfaces of the membrane (6) to scour the surfaces thereof. Apparatus for performing the method is also disclosed.

Claims

1. A method of cleaning a membrane in a membrane filtration system, the membrane filtration system including a membrane module having a drain valve, a feed inlet connected to the membrane module, a feed line having a pressure reducing device fluidly connected to the feed inlet, a source of gas fluidly connected to the pressure reducing device, and a check valve connected between the source of gas and the pressure reducing device, the method comprising:

flowing a liquid through the feed line and the pressure reducing device;

opening the drain valve to create a reduced pressure within the feed line and cause the check valve to open;

allowing a flow of gas from the source of gas to flow into the liquid to produce a liquid and gas mixture;

introducing the liquid and gas mixture into the membrane module;

scouring a surface of the membrane with the liquid gas mixture; and

flowing the gas from the source of gas into the liquid until an increase in resistance in the membrane increases the pressure within the feed line and causes the check valve to close and prevent flow of the gas from the source of gas.

2. The method according to claim 1, wherein the pressure reducing device is one of an eductor and venturi device.

3. The method according to claim 1, further comprising providing a valve responsive to an increase in resistance of the membrane to increase the flow of the liquid.

4. The method according to claim 1, further comprising selecting a flow rate of the liquid such that minimal pressure reduction is created.

5. The method according to claim 1, further comprising flowing the liquid past a supply of chemical cleaning fluid such that the reduced pressure in the feed line causes a flow of the chemical cleaning fluid from the supply of chemical cleaning fluid into the liquid.

6. A method of facilitating cleaning of a membrane filtration module having a drain valve, the method comprising:

providing an eductor having a first inlet and a second inlet;

fluidly connecting the first inlet of the eductor to a source of pressurized untreated water;

connecting the second inlet of the eductor to a source of air through a check valve configured to open when the drain valve is opened; and

connecting an outlet of the eductor to the membrane filtration module.

7. The method of claim 6, further comprising connecting an activated carbon filter to the membrane filtration module.

8. The method of claim 6, further comprising connecting a source of a cleaning fluid to the membrane filtration module.

9. A method of cleaning a membrane module having an upper drain valve, a lower drain valve, a plurality of membranes mounted therein, and an inlet fluidly connected to an eductor that is fluidly connected to an air source through a check valve, the method comprising:

opening a first valve that fluidly introduces pressurized untreated water into the eductor to produce an air-containing untreated water stream;

introducing the air-containing untreated water stream into the inlet of the membrane module;

withdrawing a treated water stream from the plurality of membranes to increase membrane resistance, decrease a flow rate of a treated water stream, and decrease a flow rate of the pressurized untreated water introduced into the educator; and

fluidly disconnecting the eductor from the air source by closing the check valve in response to the reduced flow rate of the pressurized untreated water.

10. The method of claim 9, further comprising, after closing the check valve:

discontinuing withdrawal of the treated water stream from the plurality of membranes;

increasing the flow rate of the pressurized untreated water through the educator by opening the upper drain valve and withdrawing untreated water from within the membrane module;

re-opening the check valve in response to the increase in the flow rate of the pressurized untreated water caused by opening of the upper drain valve;

producing a second air-containing untreated water stream by fluidly connecting the educator to the air source by re-opening the check valve; and

introducing the second air-containing untreated water stream into the membrane module.

11. The method of claim 10, further comprising:

closing the upper drain valve to discontinue flow of the untreated water stream from the membrane module;

raising the pressure within the membrane module by closing the upper drain valve;

after raising the pressure within the membrane module, closing the first valve to discontinue flow of the second air-containing untreated water stream into the membrane module;

after closing the first valve, opening the lower drain valve; and

withdrawing untreated water from within the membrane module through the lower drain valve.

12. The method of claim 11, further comprising:

closing the lower drain valve to discontinue flow of the untreated water from within the membrane module;

after closing the lower drain valve, opening the first valve and introducing air-containing untreated water from the eductor into the membrane module;

raising the pressure within the membrane module by introducing the air-containing untreated water into the membrane module;

after opening the first valve and raising the pressure within the membrane module,

opening the lower drain valve,

withdrawing untreated water from the membrane module through the lower drain valve,

closing the lower drain valve, and

filling the membrane module with air-containing untreated water from the eductor; and

withdrawing treated water from the plurality of membranes.

13. The method of claim 11, further comprising:

discontinuing flow of the untreated water from within the membrane module by closing the lower drain valve;

after closing the lower drain valve, opening the first valve and introducing air-containing untreated water from the eductor into the membrane module;

raising the pressure within the membrane module by introducing the air-containing untreated water into the membrane module;

after opening the first valve and raising the pressure within the membrane module,

opening the upper drain valve,

withdrawing untreated water from the membrane module through the upper drain valve,

closing the upper drain valve, and

filling the membrane module with air-containing untreated water from the eductor; and

withdrawing treated water from the plurality of membranes.

14. The method of claim 11, further comprising introducing compressed air into the membrane module while withdrawing the untreated water through the lower drain valve.

15. The method of claim 9, further comprising introducing a cleaning chemical into the membrane module.

16. The method of claim 9, further comprising, after fluidly disconnecting the eductor from the air source by closing the check valve:

discontinuing withdrawal of the treated water from the plurality of membranes;

opening the lower drain valve;

withdrawing untreated water from within the membrane module through the lower drain valve;

increasing the flow of the untreated water through the educator by withdrawing the untreated water from within the membrane module;

re-opening the check valve by increasing the flow of the untreated water through the educator;

producing a second air-containing untreated water stream by fluidly connecting the eductor to the air source;

introducing the second air-containing untreated water stream into the membrane module;

closing the lower drain valve;

discontinuing the flow of the untreated water from the membrane module by closing of the lower drain valve;

raising the pressure within the membrane module;

after raising the pressure within the membrane module, discontinuing flow of the second air-containing untreated water stream into the membrane module by closing the first valve;

after closing the first valve, opening at least one of the lower drain valve and the upper drain valve; and

withdrawing untreated water from within the membrane module through the at least one of the lower drain valve and the upper drain valve.