What is Forward Osmosis

Fundamentally, Forward Osmosis exploits a naturally occurring phenomenon (Osmosis). Which is simply the water transport over a semi-permeable membrane from a low concentration to a high concentration. In a perfect world, the semi-permeable membrane permits water to pass through it however rejects all salts and undesirable components. The high salinity solution acts as the draw solution, which has a higher concentration than the feed water. To initiate the passage and attract water to pass through the membrane from the feed side to itself. In this manner, Forward Osmosis requires less energy (applied pressure) to transport a water stream through the membrane. In comparison to the pressure driven membrane procedures, for example, reverse osmosis (RO). However, as opposed to Reverse Osmosis, the result of Forward Osmosis is not fresh water but rather a diluted draw solution. It is a blend of the feed water and draw solution. In this way, a following filtration or separation process must be performed to extract clean water and to recover the draw solution. The draw solution consists of either a single or multiple simple salts or can be a substance specifically tailored for forward osmosis applications.

The following step of filtration might be energy intensive relying upon the draw solution and the recycling procedure. Hence, for potable water production, one must consider the energy utilization of both the Forward Osmosis procedure and the DS recovery. So that we can eventually make a reasonable examination and run comps between Forward Osmosis and other water treatment advancements. Or else, the conclusion could be one-sided and deceiving. In any case, Forward Osmosis might be more practical than pressure driven membrane technologies for water reuse. Only if the recovery of the Draw Solution is not required. Consequently, Researches and developments made on Forward Osmosis will be used to organize those procedures and applications without reusing the Draw Solution.

One of the most significant applications for Forward Osmosis is done by NASA. Six forward osmosis kits will fly aboard space shuttle Atlantis on the STS-135 mission by NASA. Scientists from NASA’s Kennedy Space Center in Florida plan to test a space adapted version of a Forward Osmosis bag. This will happen aboard space shuttle Atlantis during the STS-135 mission summer 2017. The group at Kennedy, led by NASA Project Manager Spencer Woodward, will include in the shuttle’s cargo six forward osmosis bag kits for the astronauts to test. The bags’ manufacturer, made a few adaptations to their commercial product for spaceflight. The idea is to make a fortified drink that provides hydration and nutrients from all sources available aboard a spacecraft, such as wastewater and even urine.

Forward Osmosis bag kit NASA experiment

Up until today, Forward Osmosis still experiences issues as a cost-effective innovation for direct seawater desalination. As a result of its high energy utilization and absence of efficient DS with -close to – negligible reverse flux. Regardless of many innovative advances in DS recently made, challenges still exist to: First, limit the reverse flux of DS. Secondly, mitigate internal concentration polarization (ICP) and Lastly, find better and easier recovery strategies. In conclusion, Forward Osmosis represents a forthcoming technology with a very low impact on the environment.