Semipermeable Membrane Rejection Performance via Pressure Fluctuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semipermeable membranes used in seawater desalination and wastewater recycling face challenges in maintaining rejection performance due to fouling and oxidative deterioration, leading to reduced water quality and increased treatment costs, with existing recovery methods being inefficient and difficult to control in real-world operations.
Innovation Solution
A method involving the use of a liquid containing a rejection performance enhancer, such as polyethylene glycol, which is pressurized and fed to the semipermeable membrane to enhance rejection performance by altering pressure and permeation flow rate, while maintaining the changed conditions for a specific duration to improve membrane efficiency without significantly reducing water permeation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a semipermeable membrane is used for seawater desalination or wastewater recycling, then water containing solutes can be purified, but the membrane suffers from fouling and oxidative deterioration leading to reduced rejection performance
Solution Approach 1:
The patent uses polyethylene glycol as an intermediary substance that temporarily interacts with the membrane surface to restore rejection performance. The polyethylene glycol solution is circulated through the membrane, allowing the polymer to adsorb onto the membrane surface and restore its charge characteristics, thereby improving rejection of neutral molecules without permanently modifying the membrane structure
Solution Approach 2:
The patent changes the chemical environment by introducing polyethylene glycol solution at specific concentrations (0.1-10% by weight) and circulation conditions (flow rate, temperature, pH control). These parameter changes create optimal conditions for the polyethylene glycol to interact with the membrane surface and restore its performance without causing damage
2Reliability
If existing rejection performance recovery methods are used, then some performance improvement may be achieved, but the methods are inefficient and difficult to control in real-world operations
Solution Approach 1:
The patent implements a feedback control system where rejection performance is monitored (through permeate analysis or flux measurement) and the polyethylene glycol treatment is adjusted accordingly. The circulation conditions, concentration, and duration of treatment are controlled based on measured performance parameters, enabling precise and efficient restoration of membrane performance
Solution Approach 2:
The system is designed to allow the membrane to partially restore its own performance through controlled exposure to polyethylene glycol solution under specific circulation conditions. The method enables the membrane treatment process to be self-regulating within defined operational parameters, reducing the need for complex external control mechanisms
3Productivity
If pressure is increased to maintain water production, then permeate output is maintained, but rejection performance deteriorates further
Solution Approach 1:
The patent applies polyethylene glycol treatment before operating the membrane at high pressure to restore rejection performance in advance. By pre-treating the membrane with polyethylene glycol solution under controlled circulation conditions, the membrane's rejection characteristics are improved before subjected to high-pressure operation, preventing performance deterioration during production
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 effectively enhances rejection performance for nonionic substances, improving water quality by minimizing permeation performance reduction and extending the life of semipermeable membranes, thereby reducing operational costs and maintaining consistent water production.
Implementation Method 1
a liquid containing a rejection performance enhancer, such as polyethylene glycol, which is pressurized and fed to the semipermeable membrane to enhance rejection performance by altering pressure and permeation flow rate
Implementation Method 2
passing water containing a solute, such as salt, through a semipermeable membrane at a pressure not less than the osmotic pressure
Implementation Method 3
The reverse osmosis method applied to seawater desalination or recycling of sewage or wastewater can produce desalinated water by passing water containing a solute, such as salt, through a semipermeable membrane at a pressure not less than the osmotic pressure
Implementation Method 4
passing water containing a solute, such as salt, through a semipermeable membrane at a pressure not less than the osmotic pressure
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Disclosed is a method of enhancing a rejection performance of a semipermeable membrane by pressurizing and feeding a liquid containing a rejection performance enhancer to a primary side of the semipermeable membrane to come into contact with a membrane surface thereof, the method including: a step of changing, at least once during the feeding, a pressure or an osmotic pressure of the liquid containing the rejection performance enhancer at a fluctuation rate of 0.05 MPa/s or more, or a feed flow rate to the semipermeable membrane, thereby changing at least either a pressure acting on the membrane surface or a permeation flow rate from that at the time of normal treatment, followed by maintaining.