Reverse Osmosis Membrane for Low-Pressure Dialysis Regeneration
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Solution Overview
Problem
Existing dialysate regeneration methods require a large amount of adsorbent to effectively remove urea and its decomposition product, ammonia, leading to increased costs and device weight, making them unsuitable for home use.
Innovation Solution
The use of a reverse osmosis membrane element with a pore diameter of 0.7 nm or less, measured by positron annihilation lifetime measurement, allows for efficient urea separation at low operating pressures, reducing the need for adsorbent and enabling home use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adsorbent is used to remove urea and ammonia from used dialysate, then urea removal effectiveness is improved, but the amount of adsorbent required increases device weight and cost
Solution Approach 1:
The invention changes the pore diameter parameter of the reverse osmosis membrane to 0.7 nm or less, which fundamentally alters the separation mechanism from adsorption to size-based filtration. This parameter change enables effective urea removal without requiring large amounts of adsorbent, thereby reducing device weight while maintaining removal effectiveness.
Solution Approach 2:
The invention replaces the chemical adsorption mechanism with a physical filtration mechanism using reverse osmosis. By substituting the adsorbent-based chemical system with a membrane-based physical separation system, the device achieves comparable or superior urea removal effectiveness without the weight penalty of large adsorbent quantities.
2Reliability
If adsorbent is used to remove urea and ammonia from used dialysate, then urea removal effectiveness is improved, but the cost of the regeneration system increases
Solution Approach 1:
By changing the membrane pore diameter parameter to 0.7 nm or less, the invention enables a more cost-effective regeneration system. The reverse osmosis membrane technology at this pore size is commercially available and eliminates the need for expensive adsorbent materials and their associated replacement costs.
Solution Approach 2:
The reverse osmosis membrane can be replaced more economically than large quantities of adsorbent. The membrane's durability and lower replacement cost make the overall system more affordable, especially for home dialysis applications where cost sensitivity is high.
3Reliability
If high pressure is used for reverse osmosis to remove urea, then urea removal performance is improved, but energy consumption and device complexity increase
Solution Approach 1:
The invention changes the pressure parameter to a low range (0.5-2.0 MPa) by optimizing the membrane pore diameter. This parameter optimization maintains effective urea removal performance while dramatically reducing energy consumption compared to conventional high-pressure reverse osmosis systems.
4Reliability
If high pressure is used for reverse osmosis to remove urea, then urea removal performance is improved, but device complexity and size increase
Solution Approach 1:
By optimizing the membrane pore diameter parameter to 0.7 nm or less, the invention enables effective urea removal at low pressures. This parameter change simplifies the device design by eliminating the need for complex high-pressure pumps, pressure vessels, and safety systems, making the device more suitable for home use.
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
This method achieves excellent urea removal performance at low pressures, reducing the cost and weight of the dialysate regeneration device and making it suitable for home use.
Implementation Method 1
a reverse osmosis process of obtaining, from the urea-containing aqueous solution, a concentrate having a higher urea concentration and a permeate having a lower urea concentration by using a reverse osmosis membrane element
Implementation Method 2
the reverse osmosis membrane element includes a reverse osmosis membrane, and the reverse osmosis membrane has a pore diameter of 0.7 nm (7.0 Å) or less
Data Source
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AI summary
The present invention provides a dialysis solution regeneration method that exhibits high urea elimination performance even under a low-pressure operation and that can be simply used even at home. This dialysis solution regeneration method is a method for reducing urea concentration in an aqueous solution containing urea, and comprises a reverse osmosis step of using a reverse osmosis membrane element to obtain, from the aqueous solution containing the urea at an operation pressure of between 0.5 MPa and 2.0 MPa inclusive, a concentrated solution having a higher urea concentration and a permeate solution having a lower urea concentration. The aqueous solution containing the urea has a urea concentration of 0.5 g/L or higher, the reverse osmosis membrane element has a reverse osmosis membrane, and the reverse osmosis membrane has a pore diameter of 7.0 Å or less as measured using positron annihilation lifetime spectroscopy.