Cross-Flow Diafiltration Layout for Continuous Food Liquid Processing

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Solution Overview

Problem

Existing diafiltration processes are discontinuous, requiring batch processing and leading to inefficiencies due to the need for interrupting the process to add diafiltration medium, which is economically and operationally suboptimal.

Innovation Solution

A crossflow filtration unit designed for continuous diafiltration, incorporating specific filter materials and configurations that allow for continuous addition of diafiltration medium, ensuring a stable flow path and reduced pressure drop, enabling efficient and uninterrupted diafiltration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If discontinuous diafiltration is used, then the process can be performed with conventional filtration equipment, but the process requires interruption to add diafiltration medium leading to reduced productivity

Engineering Contradiction:
Improveprocess simplicityVSAvoiddiafiltration efficiency
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The device segments the flow path into distinct regions: a retentate gap for continuous feed liquid flow, a diafiltration medium addition point, and a permeate collection gap. This segmentation allows simultaneous filtration and diafiltration medium addition without process interruption, resolving the contradiction between process simplicity and productivity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The device enables continuous diafiltration by maintaining constant flow through the retentate gap while continuously adding diafiltration medium and removing permeate. The cross-flow configuration ensures uninterrupted filtration action, eliminating the batch-wise interruptions inherent in conventional methods and thereby improving productivity

Inventive Principle:
Principle #20Continuity of useful action

2Device complexity

If batch processing is used, then equipment requirements can be simplified, but the process requires complete processing of defined volume before new cycle begins leading to loss of time

Engineering Contradiction:
Improveequipment structureVSAvoidprocess cycle time
Core Design Contradiction:
Device complexityVSLoss of time

Solution Approach 1:

The device transitions from batch to continuous operation by maintaining constant feed liquid flow through the retentate gap and continuous permeate removal. The cross-flow configuration with dedicated inlet/outlet positions enables uninterrupted processing, eliminating cycle completion and restart delays, thus reducing time loss while maintaining manageable equipment structure

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The device employs dynamic flow control with adjustable inlet positions for feed liquid and diafiltration medium, and adjustable outlet positions for retentate and permeate. This dynamic configuration allows optimization of flow rates and pressure distribution, enabling continuous operation with controlled processing parameters while reducing overall process cycle time

Inventive Principle:
Principle #15Dynamics

3Device complexity

If conventional filtration configuration is used, then the structure can be simple, but the pressure drop increases and flow stability decreases

Engineering Contradiction:
Improvefiltration structureVSAvoidflow stability
Core Design Contradiction:
Device complexityVSStability of the object's composition

Solution Approach 1:

The device segments the filtration structure into a retentate gap with controlled width, separated from the permeate collection gap by the filter medium. This segmentation creates distinct flow channels that maintain stable flow patterns and reduce pressure drop while keeping the overall structure relatively simple

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The device transitions from conventional vertical filtration to a horizontal cross-flow configuration. The feed liquid flows horizontally across the filter medium surface in the retentate gap, while permeate is collected in a separate horizontal gap. This dimensional change improves flow stability and reduces pressure drop without significantly increasing structural complexity

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The crossflow filtration unit achieves improved diafiltration results with reduced process times and equipment requirements, facilitating continuous operation and enhancing the recovery of valuable materials from fluids.

Implementation Method 1

a planar first filter material (4), a retentate gap, a planar second filter material (6), arranged such that the planar first filter material (4) separates the diafiltration gap and the retentate gap from each other and the planar second filter material (6) separates the retentate gap and the permeate collection gap from each other

Methodology Applied
Scientific EffectFiltration: Filter (physical)

Implementation Method 2

In crossflow filtration, which can also be referred to as transverse or tangential flow filtration, a feed liquid to be filtered flows tangentially over the surface of a filter material, which is usually a membrane, and is thereby split into a retentate (concentrate) and a permeate (filtrate) of different compositions

Methodology Applied
Scientific EffectCross-flow filtration: Filter (physical)

Implementation Method 3

Diafiltration combines this separation with the addition of a diafiltration medium to the food liquid/retentate. This makes it possible, for example, to remove the other substances from a solution containing the target substance(s) and one or more other substances

Methodology Applied
Scientific EffectDiafiltration: Filter (physical)

Implementation Method 4

The permeate flows through the membrane perpendicular to the surface and is then removed. Target substances to be recovered can be contained in the permeate (permeate substances) and/or in the retentate (retentate substances)

Methodology Applied
Scientific EffectPermeation: Permeation

Data Source

PatentEP4509206B1Cross-flow filtration for continuous diafiltration
Publication Date: 2025.11.12 SARTORIUS STEDIM BIOTECH GMBH
  • EP4509206B1 patent drawingFigure 1
  • EP4509206B1 patent drawingFigure 2
  • EP4509206B1 patent drawingFigure 3

AI summary

The present invention relates to a method for diafiltration using a crossflow filtration unit for the continuous diafiltration of a food liquid to obtain a retentate and a permeate.