Switchable Forward Osmosis Draw Solution for High TDS Wastewater
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Solution Overview
Problem
Current water treatment methods for industrial wastewater, particularly produced water from oil and gas industries, are energy-intensive and inefficient, with high costs and environmental concerns, as they struggle to handle high TDS and complex feed streams effectively.
Innovation Solution
A switchable forward osmosis system using an aqueous draw solution with ionized trimethylamine and a counterion, which operates at lower energy inputs and facilitates the separation of water from high TDS feed streams by employing a semi-permeable membrane and a process for isolating and reconstituting the draw solute, allowing for efficient water recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If reverse osmosis is used to treat high TDS wastewater, then water separation is achieved, but energy consumption increases and membrane fouling occurs
Solution Approach 1:
The patent inverts the conventional reverse osmosis approach by using forward osmosis, where water naturally flows from low solute concentration to high solute concentration through a semi-permeable membrane driven by osmotic pressure gradient, eliminating the need for high external hydraulic pressure and significantly reducing energy consumption
Solution Approach 2:
The patent employs switchable draw solutes that can reversibly change their osmotic pressure parameters between high and low states. The draw solute is activated to create high osmotic pressure for water recovery, then deactivated and removed, allowing the system to maintain high water recovery efficiency while reducing energy consumption during the draw solute removal phase
2Quantity of substance
If conventional forward osmosis with non-switchable draw solutes is used, then water recovery is achieved, but draw solute removal requires energy-intensive processes
Solution Approach 1:
The patent utilizes phase transition of the draw solute from ionic form (in solution) to non-ionic gaseous form through thermal decomposition or chemical reaction. This phase change enables easy separation of the draw solute from the purified water by simple venting or gas-liquid separation, eliminating energy-intensive distillation or evaporation processes
Solution Approach 2:
The patent employs switchable draw solutes that can be easily generated, used, and then decomposed or removed. The draw solute serves its purpose during water recovery, then is deactivated and removed at low cost, effectively treating the draw solute as a disposable component that enables the process without requiring expensive recovery operations
3Productivity
If high concentration draw solutions are used in forward osmosis, then water flux increases, but draw solute removal becomes more difficult
Solution Approach 1:
The patent uses switchable draw solutes that can be concentrated to high levels during the water recovery phase to maximize water flux, then easily converted to a removable form. The ability to switch between high concentration ionic state (for productivity) and low concentration non-ionic state (for easy removal) resolves the contradiction between achieving high water flux and maintaining ease of draw solute isolation
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
The system effectively treats complex industrial wastewater with high TDS, reducing energy consumption and environmental impact by achieving significant water recovery and purification, even with challenging feed streams that are difficult for traditional methods to handle.
Implementation Method 1
forward osmosis using an aqueous draw solution having a draw solute concentration of ≥20 wt%
Implementation Method 2
the draw solute comprises ionized trimethylamine and a counter ion
Data Source
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AI summary
The present application provides a switchable forward osmosis system, and processes thereof. In particular, this application provides a process for treating an aqueous feed stream, comprising: forward osmosis using an aqueous draw solution having a draw solute concentration of ≥20 wt%, the draw solute comprising ionized trimethylamine and a counter ion; wherein, the feed stream: (i) comprises ≥5wt% total dissolved solids; (ii) is at a temperature of ≤20°C; (iii) is at a temperature between ≥30°C - ≤60°C; (iv) has an acidic pH or a basic pH; (v) comprises organic content; (vi) comprises suspended solids; (vii) or any combination of two or more of i) - v). Also provided herein are the related system and draw solution for performing the process, and various uses thereof for treating typically difficult to dewater feed streams.