Articles
The Scope of Forward Osmosis In Water Treatment
by Jose Malave I am an author.Reverse Osmosis is the opposite of the naturally occurring osmosis
process achieved by inducing high pressures. While this has been used in water
treatment for some time now, forward osmosis is gaining momentum for the past
few years. Today, it is actively used for treating wastewater and enabling zero
or minimal liquid waste discharge for industries.
The FO
Process:
In FO, the driving force is the draw solution which is more
concentrated than the feed. The net flow of water molecules from the feed
solution through the semi-permeable membrane is induced by a higher concentration
of the draw solution. This semi-permeable membrane is very selective to water
molecules.
In FO, solute diffusion is possible in both directions. The
diffusion happens based on the composition of both the solutions. This means
the draw solutes may diffuse to feed and vice versa. For any particular FO
process therefore, the required permeate water and concentration of the feed
plays a very important role in designing the concentrate of the draw
solution.
Unlike in RO, the membrane between the two solutions simply results in
the trade of solutes between them. Depending on the concentration of the feed and
the intended purpose of the FO process, trade is all that may be required from it.
This is also called engineered or manipulated osmosis due to the adjustment of
concentrate in draw solution to obtain required permeate water.
Applications
Forward Osmosis Applications include but are not
restricted to:
·
Emergency
drinks or hydration bags: FO is a
helpful tool in emergency situations. With enough time for contact, the
membrane readily rejects contaminants to allow passage of water to the draw
solution. Once it is diluted enough, it can be ingested directly. The
concentrates in the bag are mostly glucose, fructose, and other sugar
compounds.
·
Desalination: FO in a combination of membrane separation,
physical or thermal, can produce a diluted draw solution. It has an advantage
of low fouling which is a big problem with membranes in conventional RO desalination plants. National
Geographic cited this process as one of the three promising technologies that
can reduce the energy consumption of desalination plants in 2010.
·
Evaporative
Cooling Towers: In this
process, the coolant is used as the draw solution and the evaporated water is
replaced by brackish or seawater. The energy consumption is lower and fouling
is comparatively very low in forward osmosis.
·
As
Pre-treatment Process: FO is an asset
in pre-treatment of feed water before it goes through RO. Used as FO/RO, it removes major fouling
components before they reach the RO membrane. This saves a lot of energy in RO.
·
Retention Of
Required Compounds: FO is the
only process that helps retain essential compounds. The draw solution
concentrate can be designed to retain aromas, flavors, nutrients, and colors.
This is very helpful in the dairy, beer brewing, coffee brewing, and beverage
industry.
Sponsor Ads
About Jose Malave 
I am an author.
77 connections, 0 recommendations, 174 honor points.Joined APSense since, August 12th, 2014, From New York, United States.
Created on Jan 16th 2020 22:43. Viewed 309 times.
