This document discusses forward osmosis, an osmotic process that uses a semi-permeable membrane to separate water from dissolved solutes. It operates using an osmotic pressure gradient, drawing water through the membrane into a high-concentration draw solution. Forward osmosis requires low pressure and energy. Applications discussed include emergency drinking water production using various draw solutions, desalination, and generating osmotic power. Advantages are high recovery, low fouling, and ability to treat complex wastewater. Disadvantages include concentration polarization and reverse salt flux challenges. The future of forward osmosis lies in improving membrane technology to make it more flexible and cost-effective for general industrial use.

1. Advanced Separation Processes
(3160507)
FORWARD OSMOSIS
CHEMICAL ENGINEERING DEPARTMENT
VISHWAKARMA GOVERNMENT ENGINEERING COLLEGE
YEAR 2021-22
Presented By:
Sr.
No.
Enrollment No. Name
1 190170105021 Naitik Khatri
2 190170105029 Gopi Paghdal
3 190170105031 Mohit Pandit
4 190170105047 Parth Patel
5 200170105516 Keval Rathod
Guided By: Ujwala P. Christian

2. CONTENTS
1. Applications
1. Emergency Drinks
2. Desalination
3. Osmotic power
1. Industrial usage
1. Advantages
2. Disadvantages
3. Industrial market and future

3. ● The driving force for this separation is an osmotic
pressure gradient, such that a 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.
Key features:
● High rejection (like RO membrane)
● Low pressure (low energy consumption)
● Low fouling
● Potential for resource recovery
● Forward osmosis (FO) is an osmotic process that, like reverse osmosis (RO), uses semi-
permeable membrane to effect separation of water from dissolved solutes.
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4. ● In contrast, 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.
● Hence significantly more energy is required for reverse osmosis compared to forward
osmosis.
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5. ● The simplest equation describing the relationship between osmotic and hydraulic pressures and
water (solvent) flux is:
where, Jw is water flux,
A is the hydraulic permeability of the membrane
Δπ is the difference in osmotic pressures on the two sides of the membrane,
ΔP is the difference in hydrostatic pressure.
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6. ● In FO processes we may have solute diffusion in both directions depending on the composition
of the draw solution and the feed water.
● This does two things;
○ The draw solution solutes may diffuse to the feed solution and
○ The feed solution solutes may diffuse to the draw solution.
Clearly these phenomena have consequences in terms of the selection of the draw solution
for any particular FO process.
● The forward osmosis process is also known as osmosis or in the case of a number of
companies who have coined their own terminology 'Engineered Osmosis' and 'Manipulated
Osmosis'.
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7. Applications
Emergency drinks
● The drinking water bags are made from a combination of polypropylene
plastic (PP) and aluminum foil plastic with the interface of the FO
membrane inside.
● The drinking water bag can be applied to purify dirty water and seawater
into energy drinking water, which can be used for drinking water supply in
an emergency situation.
● Energy drinks water is produced from the FO process using a variety of
draw solution, specifically glucose, fructose, and sucrose.
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8. Desalination
● Desalinated water can be produced from the osmotic
agent solution.
● This may be by membrane separation, thermal method,
physical separation or a combination of these
processes.
● Most organic fouling in FO desalination process is
reversible. Both feed and draw solution can influence
the scaling formation and its reversibility.
● Modern water plc (a British company) has deployed
forward osmosis based desalination plants in Gibraltar
and Oman.
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9. Osmotic Power
● Osmotic power, or salinity gradient power, uses the natural process of osmosis to
generate electricity.
● This increases the pressure on one side of the membrane. Use of this pressure to
generate power was proposed in the 1970s, but a better membrane was needed to make
it cost-effective.
● In 2009, the Norwegian company Statkraft opened the first prototype.
● They are able to generate electricity continually
regardless of weather conditions, and no pollutants
are produced, which makes them reliable sources
of green electricity.
Plant size : a football field would power 30,000
households.
Osmotic power : up to 1700 TWh
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10. Industrial Usage
Advantages
● High water recovery.
● Low operational pressure.
● Low energy consumption per unit of water recovered.
● Low operation and maintenance costs.
● Less fouling and scaling (High COD Tolerance)
● Ability to treat complex wastewater.
● Modular structure.
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11. Disadvantages
Forward Osmosis suffer from two main problems,
● Concentration Polarization (CP)
● Reverse Salt Flux
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12. Industrial market and future
● Currently the industry uses few FO membranes processes (and membranes technologies in
general) as they’re complex processes which are also expensive and require a lot of
cleaning procedures and that sometimes only work under certain conditions that in industry
can’t always be ensured.
● For that reason the focus for the future in membranes is to improve the technology so it’s
more flexible and suitable for general industrial usage.
● This will be done by investing in research and by slowly getting these developments into the
market so the production cost is lowered as more membranes are produced.
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13. References
Slide 3-6 : Lee, K (1981). "Membranes for power-generation by pressure-retarded
osmosis". Journal of Membrane Science.
Slide 7-12 : Salter, R.J. (2005). "Forward Osmosis".Water Conditioning and Purification.
Kessler, J.O.; Moody, C.D. (1976). "Drinking water from sea water by forward
osmosis". Desalination.