The main drawback of the Forward osmosis (FO) desalination system is the lack of efficient draw solution recovery process.
How does the recovery unit take out the draw solution from the potable water?
Dear Nabil,
In the case of the forward osomosis, the driving force for the separation is an osmotic pressure gradient, such that a "draw" solution of high concentration (relative to that of the feed solution), is used to induce a net flow of water through the membrane into the draw solution, thus effectively separating the feed water from its solutes. In the contrary, the reverse osmosis process uses hydraulic pressure as the driving force for separation, which serves to counteract the osmotic pressure gradient that would otherwise favor water flux from the permeate to the feed.
https://en.wikipedia.org/wiki/Forward_osmosis
http://idadesal.org/wp-content/uploads/2014/10/140824-Nicoll-IDA-Whte-Paper-Forward-Osmosis-A-Brief-Introduction.pdf
http://www.nature.com/articles/srep21653
Hoping this will be helpful,
Rafik
Dear Nabil
Osmosis is a physical phenomenon that has been extensively studied by scientists in various disciplines of science and engineering.
Please for more details concerning your question, check the publication entitled: Forward osmosis: Principles, applications, and recent developments.Tzahi Y.et al.
Journal of Membrane Science 1-18 (2006). Direct link: http://www.statkraft.no/globalassets/old-contains-the-old-folder-structure/documents/forward-osmosis-in-jms_tcm9-24575.pdf.
Cordialy
Marius
Dear Dr Somda,
Thank you for your help, I've downloaded the article and I'll let you know in case if I need more explanation.
Regards,
Dear Professor Rafik,
Thank you very much indeed for your generous cooperation , definitely, this is helpful !
Regards,
Dear Nabil,
In my understanding, the methods used to separate the draw solute from water after FO depend on the properties of the draw solutes. For the commonly used inorganic salts, such as NaCl, RO is used. For the synthetic draw solutes which are the research focus in recent years, the posttreatment approaches are diverse. For example, magnetic nanoparticles which have been used as draw solutes can be separated from water via a external magnetic field. The following links are for your reference
http://www.sciencedirect.com/science/article/pii/S0376738813002494
http://pubs.acs.org/doi/abs/10.1021/ie101013w
Dear Professor Qingchun Ge,
Thank you very much indeed for these valuable articles.
Regrdas,
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