Method of maintaining clean vertical skeins of hollow fiber membranes and system therefor

• US 6,319,411 B1
• Filed: 10/07/1999
• Issued: 11/20/2001
• Est. Priority Date: 10/09/1998
• Status: Expired due to Term

• Current Assignee: Zenon Technology Partnership
• Original Assignee: Zenon Environmental Incorporated
• Inventors: Cote, Pierre Lucien
• Primary Examiner(s): POPOVICS, ROBERT J
• Application Number:
  US09/414,370
• Time in Patent Office: 775 Days
• Field of Search: 210/636, 210/650, 210/651, 210/652, 210/321.67, 210/321.69
• 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 2321/18 Use of gases
• 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 63/043 with separate tube sheets
• CPC Class Codes: B01D 63/16 Rotary, reciprocated or vibrated modules
• 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 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: C02F 1/444 by ultrafiltration or microfiltration
• CPC Class Codes: C02F 1/74 with air aeration of stretches of water C02F7/00

Abstract

This invention teaches a system and method to improve the renewal of water being filtered and to prevent the accumulation of solids within a cassette of multiple vertical skeins of hollow fibers used in membrane filtration.

Claims

1. A method for removing concentrated solids from within a vertical skein of shell-less, immersed hollow fiber membranes used for the filtration of water containing suspended solids, said method comprising;

i) assembling multiple skeins in side-by-side relationship in a cassette in an unrestrictive reservoir, each skein comprising multiple generally parallel arrays of vertical fiber membranes;

ii) concentrating solids within skeins of the cassette by creating a differential pressure across walls of the hollow fibers to filter the water flowing in tangential flow, parallel to the surface of the membranes; and

,

iii) generating an oscillating movement of the cassette about its central transverse axis located above the skeins causing the cassette to travel in an arc, at a frequency sufficient to renew water around the skeins by inducing a substantially vertical flow of the water upwards or downwards through the skeins, and flow of permeate through the fibers parallel to the bubble-generated flow when the angulating vertical axis of the oscillating cassette passes through the central vertical axis.

2. The method of claim 1 where at least a portion of vertical flow is induced by gas generating means located beneath the skeins and frequency is sufficient to promote the transport of solids from within skeins into the water surrounding the skeins.

3. The method of claim 2 including providing additional vertical flow induced by a pump or a mechanical agitator.

4. The method of claim 1 where the vertical flow corresponds to an average velocity of between 0.05 to 1.0 m/sec.

5. The method of claim 1 where the frequency of oscillation is in the range from about 4 seconds to 1 minute on each side of the vertical axis.

6. The method of claim 1 wherein oscillation is through an angle in the range from about 5°

to 35°

on either side of the vertical axis.