Osmotic Pressure Assisted Reverse Osmosis for Lower-Pressure Purification
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Solution Overview
Problem
Existing reverse osmosis and forward osmosis processes are energetically expensive and inefficient, particularly in desalination and water purification, due to high hydrostatic pressure requirements and costly evaporation and crystallization processes.
Innovation Solution
The implementation of an osmotic pressure assisted reverse osmosis (OsARO) process using a semipermeable membrane with a first feed solution having higher osmotic pressure than a second feed solution, reducing the need for high hydrostatic pressure by leveraging osmotic pressure to drive solvent flow across the membrane, thereby concentrating the first feed solution and diluting the second.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If reverse osmosis is used to purify water by removing salts, then purification quality is improved, but energy consumption increases due to high hydrostatic pressure requirements
Solution Approach 1:
The patent combines forward osmosis and reverse osmosis into a hybrid system. The FO component pre-concentrates the feed solution using osmotic pressure, while the RO component completes the purification. This merging allows the system to achieve high purification quality while reducing the energy consumption compared to conventional RO alone, as the FO stage operates at low pressure and the RO stage handles a smaller volume of concentrated solution.
Solution Approach 2:
The forward osmosis component performs preliminary concentration of the feed solution before it enters the reverse osmosis stage. By pre-concentrating the solution using osmotic pressure in the FO stage, the system reduces the volume and concentration that the high-pressure RO stage must handle, thereby reducing overall energy consumption while maintaining purification quality.
2Use of energy by moving object
If forward osmosis is used to move water through a semipermeable membrane, then energy consumption is reduced, but purification effectiveness is insufficient as water is only moved from one solute set to another
Solution Approach 1:
The patent merges forward osmosis and reverse osmosis components into a hybrid system. The FO component provides low-energy water transport, while the RO component delivers effective purification by removing salts. This combination allows the system to achieve both low energy consumption and high purification effectiveness, overcoming the limitations of using either process alone.
Solution Approach 2:
The reverse osmosis component acts as an intermediary that completes the purification process initiated by forward osmosis. While FO moves water efficiently with low energy, it doesn't achieve complete purification. The RO stage serves as the intermediary step that removes the remaining salts and contaminants, ensuring effective purification while maintaining the energy efficiency benefits of the FO stage.
3Quantity of substance
If zero liquid discharge systems use evaporation and crystallization to concentrate solutes, then concentration capability is improved, but cost increases significantly
Solution Approach 1:
The patent replaces the thermal evaporation and crystallization processes with a membrane-based osmotic system. Instead of using expensive and energy-intensive evaporation equipment, the system uses semipermeable membranes with forward and reverse osmosis to achieve high concentration capability. This substitution dramatically reduces both equipment cost and operational expenses while maintaining effective solute concentration.
Solution Approach 2:
The system changes the operating parameters from high-temperature evaporation to low-pressure osmotic processes. By operating at ambient or near-ambient temperatures with controlled pressure differentials, the system achieves high concentration capability without the capital and operational costs associated with thermal evaporation and crystallization equipment.
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
OsARO achieves a more energetically efficient process by reducing the required hydrostatic pressure, allowing for incremental concentration of solutes and purification of solvents, such as water, with lower energy consumption.
Implementation Method 1
In forward osmosis processes, the water is drawn through the semipermeable membrane using a draw solution with higher osmotic pressure than the feed
Implementation Method 2
Certain membranes allow solvent molecules to pass through them but not solute molecules. Such membranes are referred to as semipermeable
Implementation Method 3
By applying an even greater pressure, the osmotic process can be reversed. In this instance, solvent flows from the concentrated solution (such as sea water) through the semipermeable membrane to the more dilute solution
Implementation Method 4
The process of reverse osmosis has also been applied in water purification technologies
Data Source
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Figure 3A~3E
AI summary
Devices, methods, and systems for producing a concentrated feed stream and a diluted feed stream using a solute stream provided to the low pressure side of the semi-permeable membrane during a reverse osmosis process. The process includes providing a semipermeable membrane having a first side and a second side and introducing a first feed solution stream on the first side of the membrane and a second feed solution stream on the second side, wherein the osmotic pressure of the of the first feed solution stream is greater than or equal to the osmotic pressure of the second feed solution stream. The process further includes exerting hydrostatic pressure on the first side of the membrane such that solvent passes from the first side to the second side thereby producing a concentrated first feed solution stream and a diluted second feed solution stream. Devices and systems for performing the processes are provided.