Reverse osmosis is basically the process of
forcing a solvent particularly from a region of very high solute concentration
via a membrane to a region of very low solute concentration particularly by
applying an absolute pressure in excess of the respective osmotic pressure.
This is actually the reverse of the osmosis process that is quite normal, which
is basically the natural movement of solvent from an area of very low solute
concentration, via a membrane, to an area of particularly high solute
concentration when absolutely no external pressure is been applied. The
membrane here is called semipermeable, meaning it allows the complete passage
of solvent but not exactly of solute.
To illustrate, let us imagine a
semi-permeable membrane contains fresh water on one side and an aqueous
solution that is concentrated on the other side. If osmosis that is normally
taking place, the fresh water will basically cross the membrane to completely
dilute the solution that is concentrated. In Commercial RO Plant, the entire pressure is basically exerted on
the side with the solution that is concentrated to force the molecules of the
water across the membrane to the complete fresh side of the water.
The membranes generally used for systems of
reverse osmosis have quite a dense polymer barrier layer particularly in which
separation takes usually place. Since Reverse Osmosis does not generally occur
quite naturally, it must be created by properly applying pressure to the high
solids water basically in order to force it via the membrane, with pressures
ranging from 8 - 14 bar for completely fresh and brackish water, and range of
40 - 70 bar for seawater, that has around 24 bar osmotic pressure that is
natural which must be overcome. There are a lot of Commercial RO Plant Manufacturer or RO Plant Manufacturer in the market.
Design
Considerations for Reverse Osmosis Plant:-
Fluid Systems Reverse Osmosis Plants work
on the method of the Crossflow Filtration, which usually takes the feed water
and uses a bit percentage of it as a reject or washes stream, removing the solids
during the process of filtration.
The product flow of a Reverse Osmosis Plant
is mainly a function of pressure and temperature. System recovery, that is
product divided by feed is quite limited by the characteristics of the water of
the feed and can be easily controlled through the use of recycle stream.
Source:
https://www.reddit.com/user/Kelvinwater/comments/bmg73f/design_considerations_and_indepth_review_of/
