Forward Osmosis Draw Solution Energy Reduction
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Solution Overview
Problem
Current forward osmosis systems require equivalent energy to reverse osmosis for producing clean water from contaminated water, despite offering improved reliability and maintenance benefits, and face inefficiencies with traditional draw solutions.
Innovation Solution
Employing a non-aqueous draw solution with a low boiling point, such as acetone or ammonia, in a forward osmosis system that incorporates a low-energy evaporation step to recover pure water, using a semipermeable membrane to separate water from dissolved solutes without external pressure, and utilizing a condenser to recycle the draw solution solvent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional draw solutions are used in forward osmosis systems, then the system can separate water from dissolved solutes, but the energy required for water purification is equivalent to reverse osmosis
Solution Approach 1:
The patent changes the physical parameters of the draw solution by using a non-aqueous liquid with a lower boiling point than water. This parameter change enables the draw solution to be removed from the feed water at a lower temperature, reducing the energy required for the separation process while maintaining the reliability benefits of forward osmosis.
Solution Approach 2:
The patent utilizes phase transitions of the non-aqueous draw solution solvent, which evaporates at a lower temperature than water. This phase transition property allows for energy-efficient separation of water from the draw solution, reducing overall energy consumption while preserving the reliability advantages of forward osmosis systems.
2Productivity
If higher concentrations of dissolved solids are used in the draw solution, then the osmotic pressure gradient increases and water separation improves, but more energy is required to recover water from the draw solution
Solution Approach 1:
The patent changes the boiling point parameter of the draw solution solvent to be lower than that of water. This enables the draw solution to be removed at lower temperatures, reducing the energy input required for recovery while maintaining high water separation efficiency through the osmotic pressure gradient.
Solution Approach 2:
The patent replaces high-energy mechanical recovery methods with a thermal process utilizing the lower boiling point of the non-aqueous draw solution. This substitution reduces the energy required for water recovery while maintaining productivity through the enhanced osmotic pressure gradient.
3Productivity
If higher percentages of recovered water are achieved, then water recovery efficiency improves, but more energy is required for the separation process
Solution Approach 1:
The patent exploits the phase transition at a lower boiling point of the non-aqueous draw solution to enable efficient water recovery. This phase transition mechanism allows high percentages of water to be recovered with reduced energy input compared to traditional methods, as the draw solution can be separated at lower temperatures.
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
Reduces the energy required for water purification by leveraging the vapor pressure of the non-aqueous draw solution to efficiently separate water from contaminants, lowering overall energy consumption and maintaining the reliability advantages of forward osmosis.
Implementation Method 1
evaporating a quantity of draw solution solvent in an draw solution water removal unit, thereby forming evaporated draw solution solvent
Implementation Method 2
condensing the evaporated draw solution solvent, thereby forming condensed draw solution solvent
Implementation Method 3
Forward osmosis uses a semipermeable membrane, and the force for separation of water from dissolved solutes is the osmotic pressure gradient
Data Source
AI summary
A forward osmosis system is provided. The system includes forward osmosis container having a semipermeable membrane dividing the forward osmosis chamber into a first chamber and a second chamber, a draw solution water removal unit including a quantity of draw solution solvent and water, wherein the draw solution solvent includes a nonaqueous liquid and a condenser configured to receive either water vapor or draw solution solvent vapor from the draw solution water removal unit and provide condensed draw solution solvent to the second chamber. The second chamber provides a water diluted draw solution solvent to the draw solution water removal unit. The first chamber takes in received water including a dissolved solute at an input mass per unit of volume and provides a fluid output having an output mass per unit of volume greater than the input mass per unit of volume.