Forward Osmosis Membrane Permeability Detection via Transmembrane Pressure
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Solution Overview
Problem
There is a need to detect water permeability issues in forward osmosis membranes used in dialysis fluid generation to prevent the transport of components other than water across the membrane, which can alter the composition of the produced dialysis fluid and compromise its quality.
Innovation Solution
A method and control arrangement that involve providing a flow of pure water on both sides of the membrane, monitoring transmembrane pressure, and controlling flow to maintain a constant non-zero pressure difference to determine the water permeability status of the membrane, using existing mechanical features in the dialysis solution generation apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a FO-membrane is used to produce dialysis fluid, then water consumption is reduced, but water permeability issues may go undetected and alter the composition of the produced dialysis fluid
Solution Approach 1:
The patent applies preliminary action by performing a water permeability test before the FO-membrane is used for dialysis fluid production. The method involves flowing pure water through the membrane, controlling transmembrane pressure, and measuring water flux to detect permeability issues in advance, preventing contamination of the dialysis fluid while maintaining the water conservation benefits of FO technology
Solution Approach 2:
The patent implements feedback by continuously monitoring the water flux through the FO-membrane during the permeability test and comparing it against expected values. The system provides feedback on the membrane's water permeability status, allowing operators to detect and address permeability issues before they affect dialysis fluid composition, thus ensuring reliability while maintaining water efficiency
2Measurement precision
If flow is stopped via one port to determine water permeability, then the water permeability status can be determined, but the process requires precise pressure control
Solution Approach 1:
The patent uses an intermediary approach by introducing a control arrangement that mediates between the pressure control system and the flow measurement system. This intermediary controller automatically adjusts the transmembrane pressure to maintain it at a predetermined value during the permeability test, simplifying the overall control process while ensuring precise measurement of water permeability status
Solution Approach 2:
The patent applies self-service by designing a system where the control arrangement automatically maintains the transmembrane pressure at the desired level without requiring manual intervention. The system self-regulates the pressure based on feedback from pressure sensors, enabling precise water permeability measurement while reducing operational complexity
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 approach provides a straightforward and reliable method to evaluate the water permeability status of the membrane, preventing leakage and ensuring the quality of the produced dialysis fluid by identifying and addressing any water permeability errors.
Implementation Method 1
Forward osmosis (FO) has emerged as an option for producing dialysis fluid... An osmotic pressure difference between a feed fluid (for example water or effluent from the dialysis treatment) and a draw fluid (a dialysis concentrate) separated by the FO-membrane is used for extracting pure water from the feed fluid to the dialysis concentrate
Implementation Method 2
monitoring one or more pressures indicative of a transmembrane pressure (TMP) between the feed side and the draw side... controlling flow to or from the one of the feed side and the draw side that has a stopped flow based on the monitored one or more pressures, such that the TMP is maintained constant and at a non-zero magnitude
Data Source
AI summary
Provided herein are a control arrangement and a method for determining a water permeability status of a forward osmosis (FO) membrane of a FO device in a dialysis fluid generation apparatus. The FO-membrane separates a feed side and a draw side of the FO device. The FO-device comprises a feed inlet port and a feed outlet port in fluid communication with the feed side, and a draw inlet port and a draw outlet port in fluid communication with the draw side. The method comprises providing a flow of pure water at the feed side and providing a flow of pure water at the draw side. The method further comprises monitoring one or more pressures indicative of a transmembrane pressure between the feed side and the draw side.