Reduced Backwash Volume Process

• US 20080257822A1
• Filed: 12/11/2006
• Published: 10/23/2008
• Est. Priority Date: 12/09/2005
• Status: Abandoned Application

• Current Assignee: Evoqua Water Technologies LLC
• Original Assignee: Evoqua Water Technologies LLC
• Inventors: Johnson, Warren Thomas
• Application Number:
  US12/096,279
• Publication Number:
  US 20080257822A1
• Time in Patent Office: Days
• US Class Current: 210/636
• CPC Class Codes: B01D 2311/16 Flow or flux control
• CPC Class Codes: B01D 2321/04 Backflushing
• CPC Class Codes: B01D 2321/12 Use of permeate
• CPC Class Codes: B01D 2321/185 Aeration
• CPC Class Codes: B01D 61/22 Controlling or regulating
• CPC Class Codes: B01D 65/02 Membrane cleaning or sterilisation ; Membrane regeneration

Abstract

A method of backwashing a membrane filtration module, where the module includes one or more membranes located in a feed-containing vessel. The membranes having a permeable wall which is subjected to a filtration operation wherein feed liquid containing contaminant matter is applied to one side of the membrane wall and filtrate is withdrawn from the other side of the membrane wall. The method includes the steps of suspending the filtration operation; aerating the membrane surface with gas bubbles to dislodge fouling materials therefrom; recommencing the filtration operation while suspending the flow of feed liquid to the feed-containing vessel for a predetermined period; again suspending the filtration operation; performing a liquid backwash of the membrane wall to dislodge fouling materials therefrom; removing at least some of the liquid containing the dislodged contaminant matter from the feed-containing vessel; and then recommencing the filtration operation.

Claims

1. :

A method of backwashing a membrane filtration module, said module including one or more membranes located in a feed-containing vessel, the membranes having a permeable wall which is subjected to a filtration operation wherein feed liquid containing contaminant matter is applied to one side of the membrane wall and filtrate is withdrawn from the other side of the membrane wall, the method comprising the steps of;

a) suspending the filtration operation;

b) aerating the membrane surface with gas bubbles to dislodge fouling materials therefrom;

c) recommencing the filtration operation while suspending the flow of feed liquid to the feed-containing vessel for a predetermined period;

d) suspending the filtration operation;

e) performing a liquid backwash of the membrane wall to dislodge fouling materials therefrom;

f) removing at least some of the liquid containing the dislodged contaminant matter from the feed-containing vessel; and

g) recommencing the filtration operation.

2. :

A method according to claim 1 wherein the predetermined period of step c) is determined by a required level of feed relative to said membranes.

3. :

A method according to claim 1 wherein step c) includes controlling the flow of filtrate from the system such that transmembrane pressure across said membrane wall remains below a predetermined value during said predetermined period.

4. :

A method according to claim 3 wherein the transmembrane pressure remain substantially constant.

5. :

A method according to claim 1 wherein the removing step f) includes performing a sweep or drain-down of the feed-containing vessel.

6. :

A method of backwashing a membrane filtration module, said module including one or more membranes located in a feed-containing vessel, the membranes having a permeable wall which is subjected to a filtration operation wherein feed liquid containing contaminant matter is applied to one side of the membrane wall and filtrate is withdrawn from the other side of the membrane wall, the method comprising the steps of;

a) suspending the filtration operation;

b) aerating the membrane surface with gas bubbles to dislodge fouling materials therefrom;

c) recommencing the filtration operation for a predetermined period;

d) suspending the filtration operation;

e) removing at least a portion of the liquid in the module or feed-containing vessel;

f) performing a liquid backwash of the membrane wall to dislodge fouling materials therefrom;

g) removing at least some of the liquid containing the dislodged contaminant matter from the feed-containing vessel; and

h) recommencing the filtration operation.

7. :

A method according to claim 6 wherein the predetermined period of step c) is determined by a required level of feed liquid relative to said membranes.

8. :

A method according to claim 6 wherein step c) includes controlling the flow of filtrate from the system such that transmembrane pressure across said membrane wall remains below a predetermined value during said predetermined period.

9. :

A method according to claim 8 wherein the transmembrane pressure remain substantially constant.

10. :

A method according to claim 6 wherein the removing step e) includes performing a sweep or drain-down of the feed-containing vessel.

11. :

A method according to claim 6 wherein the removing step g) includes performing a sweep or drain-down of the feed-containing vessel.

12. :

A method according to claim 6 wherein steps d) and e) are reversed in order.

13. :

A method of backwashing a membrane filtration module, said module including one or more membranes located in a feed-containing vessel, the membranes having a permeable wall which is subjected to a filtration operation wherein feed liquid containing contaminant matter is applied to one side of the membrane wall and filtrate is withdrawn from the other side of the membrane wall, the method comprising the steps of;

a) suspending the provision of feed liquid to the feed containing vessel while continuing the filtration operation for a predetermined period;

b) suspending the filtration operation;

c) aerating the membrane surface with gas bubbles to dislodge fouling materials therefrom;

d) recommencing the filtration operation while continuing to suspend the flow of feed liquid to the feed-containing vessel for a further predetermined period;

e) suspending the filtration operation;

f) performing a liquid backwash of the membrane wall to dislodge fouling materials therefrom;

g) removing at least some of the liquid containing the dislodged contaminant matter from the feed-containing vessel; and

h) recommencing the filtration operation.

14. :

A method according to claim 13 wherein the removing step g) includes performing a sweep or drain-down of the feed-containing vessel.

15. :

A method according to claim 13 wherein the predetermined period of step a) is determined by a required level of feed liquid relative to said membranes.

16. :

A method according to claim 13 wherein the further predetermined period of step d) is determined by a required level of feed liquid relative to said membranes.

17. :

A method according to claim 13, wherein step d) includes controlling the flow of filtrate from the system such that transmembrane pressure across said membrane wall remains below a predetermined value during said predetermined period.

18. :

A method according to claim 17 wherein the transmembrane pressure remain substantially constant.