Cyclic aeration system for submerged membrane modules

• US 6,881,343 B2
• Filed: 10/15/2003
• Issued: 04/19/2005
• Est. Priority Date: 10/09/1998
• Status: Expired due to Term

• Current Assignee: Zenon Technology Partnership
• Original Assignee: Zenon Environmental Incorporated
• Inventors: Rabie, Hamld R., Janson, Arnold, Singh, Manwinder, Cote, Pierre Lucien
• Primary Examiner(s): BUSHEY, CHARLES S
• Application Number:
  US10/684,406
• Publication Number:
  US 20040113293A1
• Time in Patent Office: 552 Days
• Field of Search: 261/23.1, 261/28, 261/43, 261/59, 261/64.1, 261/122.1, 261/124, 261/122.2, 210/636, 210/641, 210/644, 210/649, 210650-652, 210/138, 210/142, 210/321.67, 210/321.69, 210/321.75, 210/321.78, 210/321.79, 210/321.84, 210/321.88
• US Class Current: 210/636
• CPC Class Codes: B01D 2315/06 Submerged-type; Immersion type
• CPC Class Codes: B01D 2321/04 Backflushing
• CPC Class Codes: B01D 2321/185 Aeration
• CPC Class Codes: B01D 2321/2083 By reversing the flow
• CPC Class Codes: B01D 61/18 Apparatus therefor
• CPC Class Codes: B01D 63/02 Hollow fibre modules
• CPC Class Codes: B01D 63/024 with a single potted end
• CPC Class Codes: B01D 63/026 Wafer type modules or flat-surface type modules
• CPC Class Codes: B01D 63/043 with separate tube sheets
• CPC Class Codes: B01D 65/02 Membrane cleaning or sterilisation ; Membrane regeneration
• CPC Class Codes: B01D 65/08 Prevention of membrane fouling or of concentration polarisation
• CPC Class Codes: B01F 23/23105 Arrangement or manipulation of the gas bubbling devices
• CPC Class Codes: B01F 23/23121 having injection means, e.g. nozzles with circumferential outlet
• CPC Class Codes: B01F 23/231231 the outlets being in the form of perforations
• CPC Class Codes: B01F 23/231242 in the form of slits or cut-out openings
• CPC Class Codes: B01F 23/231265 being tubes, tubular elements, cylindrical elements or set of tubes
• CPC Class Codes: B01F 23/2319 Methods of introducing gases into liquid media
• CPC Class Codes: B01F 33/4062 with means for modifying the gas pressure or for supplying gas at different pressures or in different volumes at different parts of the bottom
• CPC Class Codes: B01F 35/145 Washing or cleaning mixers not provided for in other groups in this subclass; Inhibiting build-up of material on machine parts using other means
• CPC Class Codes: B08B 3/10 with additional treatment of the liquid or of the object being cleaned, e.g. by heat, by electricity or by vibration
• CPC Class Codes: C02F 1/444 : by ultrafiltration or microfiltration
• CPC Class Codes: C02F 1/74 : with air aeration of stretches of water C02F7/00
• CPC Class Codes: C02F 3/1273 : Submerged membrane bioreactors
• CPC Class Codes: C02F 3/201 : Perforated, resilient plastic diffusers, e.g. membranes, sheets, foils, tubes, hoses
• CPC Class Codes: Y02W 10/10 : Biological treatment of water, waste water, or sewage

Abstract

An aeration system for a submerged membrane module has a set of aerators connected to an air blower, valves and a controller adapted to alternately provide a higher rate or air flow and a lower rate of air flow in repeated cycles. In an embodiment, the air blower, valves and controller, simultaneously provide the alternating air flow to two or more sets of aerators such that the total air flow is constant, allowing the blower to be operated at a constant speed. In another embodiment, the repeated cycles are of short duration. Transient flow conditions result in the tank water which helps avoid dead spaces and assists in agitating the membranes.

Claims

1. A process for supplying bubbles to a filtering membrane and cleaning an aerator producing the bubbles, the filtering membrane being immersed in a tank containing water, the process comprising the steps of:

a) flowing a gas to an aerator to produce a pressure in the aerator sufficient to produce bubbles from the aerator which contact the filtering membrane;

b) reducing the pressure in the aerator by venting the aerator to atmosphere through a conduit, such that water in the tank enters the aerator,

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

2. The process of claim 1 wherein step b) comprises reducing the rate of flow of gas to the aerator by at least half.

3. The process of claim 1 wherein step b) comprises stopping the flow of gas to the aerator.

4. The process of claim 1 wherein the aerator is vented to atmosphere by opening a valve in a pipe in communication with the aerator.

5. The process of claim 1 wherein step b) is performed periodically, successive performances of step b) being separated by a pre-determined time interval.

6. The process of claim 1 wherein the aerator has holes in its bottom surface.

7. The process of claim 1 wherein the tank water that enters the aerator during step (b) wets solids accumulated in the aerator during step (a).