Waste water treatment apparatus and washing method thereof

• US 5,690,830 A
• Filed: 06/24/1996
• Issued: 11/25/1997
• Est. Priority Date: 08/26/1993
• Status: Expired due to Fees

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: Tada, Naoki, Inoue, Kenichi, Kawashima, Toshiyuki, Ohtani, Akira
• Primary Examiner(s): FORTUNA, ANA M
• Application Number:
  US08/668,719
• Time in Patent Office: 519 Days
• Field of Search: 210/636, 210/691, 210/650, 210/195.1, 210/257.1, 210/333.01, 210/333.1, 210/799, 210/652, 210/257.2, 210/134, 210/97, 210/106, 210/321.69
• US Class Current: 210/636
• CPC Class Codes: B01D 2321/12 Use of permeate
• CPC Class Codes: B01D 2321/185 Aeration
• CPC Class Codes: B01D 65/02 Membrane cleaning or sterilisation ; Membrane regeneration

Abstract

A waste water treatment apparatus which can discharge cleaned waste water while separating and recovering insoluble granular components such as emulsions contained in various kinds of waste waters and various kinds of industrial waste waters, while minimizing the decrease of permeation flux by an effective separation membrane washing, and a washing method of the apparatus are disclosed. In washing the separation membrane, a passageway for water permeated through the separation membrane is intercepted, and a compressed gas is introduced into at least a waste feeding side of the separation membrane for a predetermined time, thereby flowing a gas liquid mixed liquid.

Claims

1. A waste water treatment apparatus for separating and removing insoluble, granular material from waste water, comprising:

a separation membrane having a feed side and a permeate side, wherein said separation membrane has a spiral-wound module structure;

a waste water inlet in fluid communication with said feed side of said separation membrane for introducing said waste water to said separation membrane;

a permeated water outlet in fluid communication with said permeate side of said separation membrane for receiving permeated water from said separation membrane, said permeated water outlet including a first valve in said permeated water outlet located downstream from said separation membrane operable between an open position where water flows out of said apparatus and a closed position for recycling said waste water from said separation membrane to said waste water inlet;

means for introducing compressed gas into said waste water inlet to form a mixture of gas and liquid in said waste water inlet for removing said insoluble, granular material deposited on said separation membrane from said separation membrane, said compressed gas introduction means comprising;

a gas source; and

a second valve operable between an open position for introducing said compressed gas into said waste water inlet and a closed position, said second valve being located between said gas source and said waste water inlet means, and said second valve being in said open position for introducing said compressed gas into said waste water inlet when said first valve is in a closed position and for recycling said waste water and said insoluble, granular material removed from said separation membrane to said waste water inlet; and

a recycle means for recycling said waste water and said insoluble, granular material and said separation membrane is washed with said mixture of gas and liquid.

2. The waste water treatment apparatus of claim 1, further comprising means in fluid communication with said gas source for introducing said compressed gas into said permeated water outlet to form a mixture of gas and liquid in said permeated water outlet for further removal of said deposited granular material from said separation membrane by forcing said liquid in said permeated water outlet through said separation membrane from said permeate side to said feed side.

3. The waste water treatment apparatus of claim 2, further comprising a detector for detecting a change in the flow rate of water flowing through said water outlet, and a controller for selectively opening and closing both of said first valve and said second valve in response to a change in said flow rate through said water outlet.

4. The waste water treatment apparatus of claim 3, wherein said detector is a flowmeter and/or a pressure gauge located in said water outlet.

5. The waste water treatment apparatus of claim 2, further comprising a liquid-liquid separation tank in fluid communication with said waste water inlet for separating a non-aqueous phase from said waste water prior to separating and removing said insoluble granular material from said waste water.

6. The waste water treatment apparatus of claim 1, further comprising a detector for detecting a change in the flow rate of water flowing through said permeated water outlet, and a controller for selectively opening and closing both of said first valve and said second valve in response to said change in said flow rate through said permeated water outlet.

7. The waste water treatment apparatus of claim 6, wherein said detector is a flowmeter and/or a pressure gauge located in said water outlet.

8. The waste water treatment apparatus of claim 1, further comprising a liquid-liquid separation tank in fluid communication with said waste water inlet for separating a non-aqueous phase from said waste water prior to separating and removing said insoluble granular material from said waste water.

9. A waste water treatment apparatus according to claim 1, wherein the compressed gas introduction means introduces gas to the permeate side as well as to the feed side of the separation membrane.

10. A waste water treatment apparatus according to claim 9, further comprising a detector for detecting a change in the flow rate of water flowing through said waste water inlet, and a controller for selectively opening and closing both of said first valve and said second valve in response to said change in said flow rate through said waste water inlet.

11. The waste water treatment apparatus of claim 10, wherein said detector is a flowmeter and/or a pressure gauge located in said water outlet.

12. The waste water treatment apparatus of claim 9, further comprising a liquid-liquid separation tank in fluid communication with said waste water inlet for separating a non-aqueous phase form said waste water prior to separating and removing said insoluble granular material from said waste water.

13. A method for removing deposited, insoluble granular material from a separation membrane having a spiral-wound module structure of a waste water treatment apparatus, comprising the steps of:

passing waste water to a feed side of said membrane treatment apparatus to produce a permeate and retentate;

interrupting the flow of permeate through a permeate water outlet of said treatment apparatus, and introducing a compressed gas into a waste water inlet of said separation membrane to form a mixture of gas and liquid in said water inlet;

flowing said mixture of gas and liquid into contact with said separation membrane to remove said deposited, insoluble, granular material from said separation membrane; and

recycling said waste water and insoluble granular material removed from said separation back to said separation membrane;

stopping the introduction of gas into said waste water inlet;

introducing compressed gas into said permeated water outlet to form a mixture of gas and liquid in said permeate water outlet; and

flowing said mixture of gas and liquid in said permeated water outlet through said separation membrane from a permeate side of said separation membrane to a feed side of said separation membrane, to further remove said deposited insoluble granular material from said membrane.

14. The method of claim 13, further comprising the step of monitoring the change in flow rate of water in said permeated water outlet and controlling both of said introduction of compressed gas into said waste water inlet and said interruption of said flow of water in said permeated water outlet in response to a change in said flow rate.

15. The method of claim 13, further comprising the step of separating a non-aqueous phase from said waste water prior to introducing said compressed gas into said waste water inlet.