Forward Osmosis Reverse Osmosis Brine Re-concentration
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Solution Overview
Problem
Current water treatment technologies face challenges in efficiently processing and re-concentrating high total dissolved solids (TDS) brines, particularly in forward osmosis systems, which limits their ability to treat high TDS water streams like produced water from oil production, due to high operating and capital costs and membrane fouling.
Innovation Solution
A two-step or three-step water purification system that combines forward osmosis with reverse osmosis or nanofiltration, utilizing strong anionic base adsorption media and resin-embedded membranes to recycle brine streams, reducing fouling and energy costs by using fresh water for rinsing and leveraging the natural osmotic attraction of zinc or iron-based brines to concentrate brines to higher levels without high-energy evaporators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional reverse osmosis is used to treat high TDS water, then water can be purified, but pumping pressure and capital and operating costs increase significantly
Solution Approach 1:
The patent divides the water treatment process into two distinct stages: forward osmosis for initial water extraction at low pressure, followed by reverse osmosis for final purification. This segmentation allows each process to operate in its optimal pressure range, reducing overall system pressure requirements while maintaining purification quality.
Solution Approach 2:
Instead of using high-pressure reverse osmosis as the primary treatment method, the patent inverts the approach by first using low-pressure forward osmosis to extract water, then applying reverse osmosis to the concentrate stream. This inversion reduces the pressure burden on the main treatment pathway.
2Manufacturing precision
If traditional reverse osmosis is used to treat high TDS water, then water can be purified, but capital and operating costs increase
Solution Approach 1:
The patent segments the treatment process to handle different water quality requirements separately: forward osmosis treats the bulk stream at low cost, while reverse osmosis focuses resources on purifying the concentrate stream. This reduces overall operating costs by avoiding high-pressure treatment of the entire high-TDS stream.
Solution Approach 2:
The forward osmosis process uses the natural osmotic gradient between the feed water and draw solution to drive water extraction without requiring external high-pressure pumping. This self-service mechanism significantly reduces energy consumption and operating costs compared to traditional high-pressure RO systems.
3Reliability
If forward osmosis is used to draw water across the membrane, then membrane fouling is reduced, but brine re-concentration becomes challenging
Solution Approach 1:
The patent merges forward osmosis and reverse osmosis systems, using the FO process to produce clean water while the RO process handles brine re-concentration. The permeate from FO serves as feed to RO, creating an integrated system where each process compensates for the other's limitations.
Solution Approach 2:
The patent introduces an intermediary evaporation or crystallization step between FO and RO processes. This intermediary stage concentrates the brine from FO before it enters the RO system, making the subsequent RO process more efficient and reducing the complexity of direct brine re-concentration.
4Manufacturing precision
If high pressure is applied in reverse osmosis, then water purification is achieved, but energy consumption increases
Solution Approach 1:
The patent segments the energy-intensive purification task from the bulk water extraction task. Forward osmosis handles the majority of water extraction using minimal energy, while reverse osmosis focuses energy consumption only on the smaller concentrate stream requiring final purification, significantly reducing total energy consumption.
Solution Approach 2:
The forward osmosis process performs partial purification by extracting most of the water and removing a significant portion of dissolved solids. This partial action reduces the TDS load on the subsequent RO system, allowing it to achieve final purification with lower energy consumption than if it had to handle the full TDS load alone.
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 achieves high water recovery rates (up to 50-80%) and reduces operating pressures, minimizing fouling and energy consumption, enabling the treatment of high TDS water streams without the need for high-energy evaporative processes, thus providing a cost-effective and efficient method for water reuse and brine re-concentration.
Implementation Method 1
An FO system draws water across the membrane to purify it at a low pressure which reduces membrane fouling potential
Implementation Method 2
A traditional RO system pushes water at high pressure through a membrane that essentially filters out dissolved minerals and produces a clean water stream and a concentrated salt water stream
Implementation Method 3
The draw solution is contacted with strong base anion adsorption media, such as a resin, to remove the zinc or iron-based draw solutes
Data Source
AI summary
A high salinity water purification system and process, including a forward osmosis system and a reverse osmosis or nanofiltration system. A concentrated brine of a zinc or iron complex combined with a salt or acid draws pure water across the FO membrane from the influent water. The diluted brine is pumped through a vessel holding an anionic adsorption media to remove the zinc or iron complex and the resultant brine is passed through the RO or nanofiltration system to obtain purified water and a concentrated brine stream. The adsorption media is regenerated by a rinse cycle using fresh water or water from the RO system, removing the zinc or iron complex adhered to the media. The resultant brine is stored and mixed with the output of the RO system. Charged membrane can be used as a standalone membrane in FO process or in combination with resin or resin embedded membrane.