OVERVIEW OF FORWARD OSMOSIS
WHAT IS FORWARD OSMOSIS?
Forward Osmosis (FO) is a natural membrane process found in nature capable of extracting pure water from impure sources. Unlike Reverse Osmosis (RO), which uses hydraulic pressure to drive water across a semi-permeable membrane, FO uses a “draw” solution to draw water across it. FO spontaneously draws water across a membrane whenever one solution is higher in salt concentration or solute (draw solution) than another (feed solution). The difference in salt concentration between solutions is known as the osmotic gradient (Δπ) and is the free and natural energy responsible in powering the water extraction process.
As water is drawn from the feed solution into the draw solution across the semi-permeable membrane, two things occur; the feed becomes concentrated, and the draw solution becomes diluted. The result of this is a reduction in the osmotic gradient between solutions and in turn a reduction in the flow rate across the semi-permeable membrane known as flux rate. For forward osmosis to operate continuously, water drawn across the membrane into the draw solution must be removed continuously so that a maximum draw concentration can be maintained and a maximum concentration gradient achieved.
REVOLUTIONARY THREE STEP PROCESS
Forward Water Technologies has developed a unique and patented industrial FO (iFO™) technology, utilizing their revolutionary three Step process, achieving high-rate water extraction within a low energy continuous process.
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1
Water Extraction Process
Water is drawn across an FO membrane into a salt draw solution. The combination of a patented draw solution and a unique FO membrane, effectively “locks” the draw solution on one side of the membrane, making it the first true closed loop process
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2
Water/Salt Separation
The process of water/salt separation is accomplished using a patented “Switchable Water Salt” (SWS) and the use of low-grade heat (60-85°C). When low-grade heat is applied to the SWS, it phases from a liquid to a gas. As gas leaves solution, clean water is left behind. The thermal energy needed to drive this process can be from waste heat, solar thermal, geothermal or other sources.
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3
Salt Draw Reconcentration
As gas leaves solution it is captured within the system and passively cooled between 10-15°C causing it to phase back into liquid and to its original SWS concentrated form. The SWS concentrate is collected and recycled back to the FO draw inlet in Step 1, establishing a closed-loop, continuous process. Passive cooling needed to drive this process can be from cooling towers, geothermal, heat exchangers, sub-surface brines or other sources.
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ADVANCED WATER RECOVERY IN A THREE STEP PROCESS
The (3) three step process developed by Forward Water Technologies, enables iFO™ systems to achieve maximum water extraction from the most challenging process streams, using minimum energy with one of the lowest life cycle costs. Leveraging developments in chemistry, material sciences and best-in-class operations, FWTC offers the most advanced and efficient industrial forward osmosis systems available today.
Contact us and find out why clients select us as the technology of choice for water reuse, product concentration and CO2 emission reduction and how iFO™ can help you achieve your Sustainability and Net-Zero emission goals.