Find an answer to your FAQ here, or contact us today to learn more.
With a semi-permeable membrane, forward osmosis (FO) uses the natural osmotic process to separate water from dissolved solids (salts). Instead of using hydraulic pressure, the driving force for this separation is a “draw” solution of higher concentration than the feed water. The osmotic gradient between the two streams is used to create a flow of water through the membrane, allowing clean water to mix with the draw solution separating it from salt and other contaminants.
The process of osmosis uses a semi-permeable barrier (or membrane) that water diffuses across. Water flows through the membrane from a lower concentration to a higher concentration to achieve equilibrium on both sides. Osmosis and forward osmosis (FO) are the same thing. Misunderstanding occurs when people confuse forward osmosis and reverse osmosis.
Reverse osmosis (RO) uses a similar semi-permeable barrier, but instead of allowing osmosis to occur naturally, the opposite is done, and force is needed. To overcome osmotic pressure, hydraulic pressure is applied to forcefully push water through the membrane, leaving salt behind.
When one thinks about RO, high-pressure pumps, high-pressure vessels, stainless steel, and lots of energy come to mind. This is because the natural osmotic gradient must be overcome by adding further pressure to actually force water through the membrane. That’s a major difference between RO and FO – RO requires artificial force while FO uses natural osmosis.
The Oasys process is unique in two ways:
The Oasys ClearFlo MBC system uses a proprietary, recoverable draw solution comprised of thermolytic salts. Forward osmosis frequently uses a once-through draw solution, which is not recovered. Common applications include sugar as draw solution to create a sports drink, or brine as draw solution to create lower salinity brine. Instead, Oasys uses a closed loop process to recover the draw solution.
In this closed loop system, Oasys separates the draw solution from fresh water using low-grade heat. Some FO processes use RO or other membrane technologies to recover their draw solution. This, however, limits the maximum allowable brine concentration and requires additional electricity, resulting in higher energy costs. Oasys needs just enough heat (much less than what is needed to boil water) in the recovery system to change the phase of the thermolytic salt in the draw solution from liquid to vapor. Our draw recovery system is designed to ensure that no draw solution remains in the final product water or brine.
Oasys Water’s ClearFlo MBC technology is used as a brine concentrator, requiring significantly less energy and cost than an equivalent evaporator performing the same function. Oasys’ system is different because the salts in our draw solution are vaporized instead of the water, therefore requiring between 30 and 50 percent less energy than comparable technologies. Oasys systems similarly don’t require expensive or exotic materials to construct, a common problem with some evaporative systems.
The Oasys ClearFlo MBC system treats industrial produced water and wastewater with salinities three to five times that of seawater (typically 50,000 mg/l TDS to 150,000 mg/l TDS). This includes produced water from various industrial markets including oil and gas, mining drainage, chemical and petrochemical processes, power plant wastewater, and RO concentrate.
A primary difference between RO and FO membranes is its structure. FO membranes do not require the robust structural support that RO membranes do, because high pressure operation is not required for FO. This means that the membrane can be thinner and more permeable. A thinner membrane is beneficial because it helps the draw solution flow more efficiently.
Oasys uses a proprietary thin film composite membrane that has been specially tailored for FO operation and the specific chemistry of Oasys Water’s draw solution.
Yes. The ClearFlo MBC is capable of handling fluctuations in flow, TDS, and water quality. The more information we have in the design phase, the better the system will be able to handle variation and target consistent recovery even when fluctuations are present.
Unlike other brine concentration technologies, the Oasys system uses significantly less energy. The energy required for system operation can come from a variety of sources such as electricity, natural gas, waste heat from power plants, and renewable energy. Contact us to learn more.
Our system design is relatively flexible, and can be customized for client needs. Typically the system footprint increases with system capacity, however the exact layout can be designed to meet customer and facility requirements.
Our portable skid-mounded design has a smaller footprint, while our built-in-place fixed design can be integrated into an existing facility.
We currently have projects in various locations around the globe. Please contact us today if you would like to visit a site, schedule a trial for your application, or have a tour of our offices.