BACKWASH AND CLEANING METHOD

• US 20100025320A1
• Filed: 09/26/2008
• Published: 02/04/2010
• Est. Priority Date: 03/22/2006
• Status: Abandoned Application

• Current Assignee: Warren Thomas Johnson
• Original Assignee: Warren Thomas Johnson
• Inventors: Johnson, Warren Thomas
• Application Number:
  US12/238,806
• Publication Number:
  US 20100025320A1
• Time in Patent Office: Days
• US Class Current: 210/321.690
• CPC Class Codes: B01D 2315/06 Submerged-type; Immersion type
• CPC Class Codes: B01D 2321/04 Backflushing
• CPC Class Codes: B01D 2321/16 Use of chemical agents
• CPC Class Codes: B01D 2321/18 Use of gases
• CPC Class Codes: B01D 65/02 Membrane cleaning or sterilisation ; Membrane regeneration

Abstract

A method of concentrating the solids of a liquid suspension by providing pressure differential across the walls of permable hollow membranes (6) immersed in the liquid suspension (9). The liquid suspension (9) is applied to the outer surface of the porous hollow membranes (6) to induce and sustain filtration through the membrane walls (12) wherein some of the liquid suspension passes through the walls (12) of the membranes (6) to be drawn off as clarified liquid or permeate from the hollow membranes lumens (11), and at least some of the solids are retained on or in the hollow membranes (6) or otherwise as suspended solids within the liquid (9) surrounding the membranes (6). The method includes periodically backwashing the membrane pores using the permeate by applying a gas pressure below the bubble point to the membrane lumens (11) to progressively displace at least some of the liquid permeate within the lumens (11) through the membrane pores resulting in removal the solids retained on or in the hollow membranes into the bulk liquid (9) surrounding the membranes (6).

Claims

1-11. -11. (canceled)

12. A concentrator for recovering fine solids from a liquid feed suspension comprising:

(i) a vessel for containing said feed suspension;

(ii) a plurality of permeable, hollow membranes within the vessel;

(iii) means for providing a pressure differential across walls of said membranes;

(iv) means for withdrawing clarified liquid from the membrane; and

(v) means for applying gas at a pressure below the bubble point to the liquid permeate in the membrane lumens to effect a discharge of at least some of the liquid permeate in the lumens through the membrane walls to dislodge any solids retained therein and displace the removed solids into the bulk liquid surrounding the membranes.

13. A concentrator for recovering fine solids from a liquid feed suspension comprising:

(i) a vessel or tank for containing said feed suspension;

(ii) a plurality of permeable, hollow membranes within the vessel or tank;

(iii) means for providing a pressure differential across walls of said membranes;

(iv) means for withdrawing clarified liquid from the membrane; and

(v) means for applying gas pressure to the liquid in the membrane lumens and walls while the vessel or tank is exposed to atmospheric pressure and while concurrently draining liquid from said lumens, to effect firstly a discharge of liquid in the lumens through the membrane walls, and secondly a transmembrane cleaning of the membranes by applying the gas at sufficient pressure onto the liquid to overcome the bubble point of the membrane, and ensure that the gas will displace liquid and follow it through the larger pores of the membranes to dislodge any solids retained therein; and

for the emerging gas to scour the external walls of the membranes and displace the removed solids into the bulk liquid in the vessel or tank.