Spent Dialysate Regeneration With Two-Stage Filtration

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Solution Overview

Problem

Conventional dialysis machines require large and heavy RO systems for producing ultrapure water, making them difficult to transport, especially for home and portable use, and the osmotic pressure in existing systems complicates filtration efficiency.

Innovation Solution

A two-stage filtration system using a graphene filter to produce ultrapure water, where the osmotic pressure is managed by supplying concentrates to the secondary side of the filter, reducing the need for additional components and enhancing filtration efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a conventional RO system is used to produce ultrapure water, then water purification is achieved, but the system becomes large and heavy

Engineering Contradiction:
Improveultrapure water productionVSAvoiddialysis machine weight
Core Design Contradiction:
Quantity of substanceVSWeight of stationary object

Solution Approach 1:

The patent changes the operating parameters of the filtration system by using a two-stage process with different pressure conditions. The first stage operates at high pressure to remove large molecules, while the second stage operates at low pressure to remove smaller contaminants, achieving ultrapure water without requiring a heavy conventional RO system

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The water purification function is segmented into two separate filtration stages with different mechanisms. The first stage uses a filter membrane for macromolecule removal, and the second stage uses a different filtration approach for smaller contaminants, distributing the purification task across multiple lighter components rather than one heavy RO system

Inventive Principle:
Principle #1Segmentation

2Productivity

If osmotic pressure is present in the filtration system, then filtration occurs, but filtration efficiency is reduced

Engineering Contradiction:
Improvefiltration efficiencyVSAvoidosmotic pressure
Core Design Contradiction:
ProductivityVSStress or pressure

Solution Approach 1:

Instead of applying pressure to force water through the membrane (which creates osmotic pressure resistance), the patent inverts the approach by allowing water to flow naturally through the filter membrane under minimal pressure, using the concentration gradient to drive filtration in the opposite direction of conventional pressure-driven RO systems

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent replaces the mechanical pressure-driven RO system with a diffusion-based filtration mechanism. Instead of using high pressure to overcome osmotic pressure, the system uses concentration gradients and selective permeability of the filter membrane to achieve water purification without mechanical pressure resistance

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 system reduces the size and weight of dialysis machines by eliminating the need for separate RO systems and improves filtration efficiency by minimizing osmotic pressure, allowing for more effective production of ultrapure water.

Implementation Method 1

The pressure gradient between the primary side 21 and secondary side 22 of the filter 20 results in a flow through the filter membrane or other filter medium, with the filtrate on the secondary side 22

Methodology Applied
Scientific EffectOsmosis: Osmosis

Implementation Method 2

The pump 50 pumps the used dialysis solution from the container 10 to the primary side 21 of the filter 20 and the retentate back into the container 10 via the valve 60. This creates a pressure drop across the valve 60 and thus also a pressure on the filter 20

Methodology Applied
Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentEP3829676B1Device for regeneration of spent dialysate
Publication Date: 2025.10.15 FRESENIUS MEDICAL CARE DEUTSCHLAND GMBH
  • EP3829676B1 patent drawingFigure 1~2
  • EP3829676B1 patent drawingFigure 3
  • EP3829676B1 patent drawingFigure 4~5

AI summary

The invention relates to a method and to a device for producing a dialysis solution, wherein the device comprises a first circuit and a second circuit, wherein the first circuit comprises a container, for receiving the used dialysis solution or fresh water or another liquid, the primary side of a filter connected downstream of the container and a return line from the primary side of the filter into the container. The filter is designed so as to produce purified water from the used dialysis solution or from fresh water or from another liquid. The second circuit comprises the secondary side of the filter, the dialysate side of the dialyser, a reservoir, a line leading from the reservoir to the secondary side of the filter, by means of which line dialysate or a dialysate concentrate can be supplied to the secondary side of the filter, and a filtrate line which leads away from the secondary side of the filter.