Tangential-flow filtration system

• US 6,555,006 B2
• Filed: 04/12/2002
• Issued: 04/29/2003
• Est. Priority Date: 01/17/1996
• Status: Expired due to Term

• Current Assignee: Genentech, Inc. (Roche Holding AG)
• Original Assignee: Genentech, Inc. (Roche Holding AG)
• Inventors: van Reis, Robert D.
• Primary Examiner(s): FORTUNA, ANA M
• Application Number:
  US10/121,360
• Publication Number:
  US 20020108907A1
• Time in Patent Office: 382 Days
• Field of Search: 210/641, 210/636, 210/321.69, 210/257.2, 210/195.2, 210/321.75, 210/321.84, 210/321.6
• US Class Current: 210/641
• CPC Class Codes: B01D 61/14 Ultrafiltration; Microfiltration
• CPC Class Codes: B01D 61/145 Ultrafiltration
• CPC Class Codes: B01D 61/146 comprising multiple ultrafiltration steps
• CPC Class Codes: B01D 61/147 Microfiltration

Abstract

The present invention includes a system and method for transferring a selected solute species from a fluid mixture to a fluid media. The system of the present invention includes a convergent channel for passing a fluid mixture containing a selected species tangentially across the first surface of a porous membrane. A fluid media is directed to flow tangentially over the second surface of the membrane. As the fluid mixture and the fluid media flow on opposite sides of the membrane, the selected species traverses the membrane leaving the fluid mixture and entering the fluid media. The volumetric loss to the fluid mixture associated with the loss of the selected species is compensated for by the convergency of the channel. As a result a constant velocity is maintained over the membrane, maximizing the selectivity of the filtration process.

Claims

1. A tangential-flow filtration apparatus separating a fluid mixture into species of interest in a cascade mode, the apparatus comprising:

first filtration system and a subsequent filtration system, each of the filtration systems comprising;

a cassette formed with a layered sequence of side-by-side channels including a convergent first channel, a last channel, and, between the first channel and the last channel, series of intermediate channels, the convergent first channel and at least one intermediate channel being configured as recirculating channels having an inlet and outlet, the last channel being configured as a non-recirculating channel having an outlet;

a series of filtration membranes, one filtration membrane positioned between each successive pair of channels in the layered sequence with each successive pair of channels in the layered sequence being separated by a filtration membrane having a successively smaller pore size;

means for creating a flow of the fluid mixture between the inlet and the outlet of each recirculating channel of each first and subsequent filtration system in the direction of tangential flow; and

means for creating a pressure differential between each successive pair of channels in the layered sequence;

the apparatus further comprising a means for directing fluid media from the last channel of the filtration system to the first channel of the subsequent filtration system.

2. A tangential-flow filtration apparatus as recited in claim 1 wherein the cassette is formed to include one intermediate channel.

3. A tangential-flow filtration apparatus as recited in claim 1 wherein the cassette is formed to include two intermediate channels.

4. A tangential-flow filtration apparatus as recited in claim 1 wherein the outlet of each recirculating channel is connected in fluid communication to the inlet of the channel.

5. A tangential-flow filter as recited in claim 1 wherein the velocity of the flow of the fluid mixture is substantially constant within each recirculating channel.

6. A tangential-flow filter as recited in claim 1 wherein the pressure differential between each successive pair of recirculating channels in the layered sequence is maintained at a value which is less than the transition point pressure (TPP) of the tangential-flow filter.

7. A tangential-flow filter as recited in claim 1 wherein the convergent first channel is dimensioned so that the pressure differential between the convergent first channel and the intermediate channel is substantially constant over the length of the filtration membrane positioned between the convergent first channel and the intermediate channel by the species.

8. A tangential-flow filter as recited in claim 1 wherein the convergent first channel is dimensioned to compensate for volumetric changes to the fluid mixture caused by the traversal of the filtration membrane positioned between the convergent first channel and the intermediate channel by the species.