1. MEMBRANE TECHNOLOGY
Membrane technology can be traced
back to 18th century scientists. However,
during 19th and in the beginning of 20th
centuries membranes were being used
only on laboratory scale to develop
physical and chemical theories and
were not being used for industrial and
commercial purpose.

2. There were four main reasons which
prohibited the wide use of membrane
separation process, those obstacles were
1. reliability, 2. efficiency, 3. cost and 4.
limited choice,
however over the last three decades
these obstacles have been resolved and
now these days membrane separation
processes are being widely used

3. DEFINITION
Membrane technology has been proven
very effective in separation and
purification process.
A membrane can be defined as “A barrier
which separates two phases and restricts
transport of various chemicals in a
selective manner”

4. A membrane could be a homogeneous or
heterogeneous, symmetric or asymmetric, solid or
liquid in structure. Membranes can carry “a positive
or negative charge or be neutral or bipolar”.
Membrane thicknesses vary from 100 micron to
several mms. A membrane separates the feed
stream into two streams permeate and
concentrate. Permeate is the portion of main feed
stream which passes through the membrane while
the concentrate contains the material which is
rejected by the membrane

5. APPLICATIONS
• Membrane technology has wide range of application in food and
dairy industry
• Waste streams treatment
• Separation of milk fraction
• Concentrating of protein
• In cheese manufacturing to recover the protein from brine used in
washed cheese manufacturing
• In dairy industry for defatting of skimmed milk and whey streams
• For the partial demineralization of whey
• For the removal of bacteria from milk and whey
• The choice of membrane depends on the application objective,
however, the most commonly used membrane are,

6. Micro-porous membrane
These membranes are usually made up of materials
like ceramics, graphite, metal oxides and polymers
etc. The pore size of these membranes varies from
1 nm-20 microns. Membrane works like a fibre filter
and separates by sieving mechanism (Srikanth
2005). In structure and function microporous
membranes are similar to conventional filters,
however, the pore size is very smaller as compared
to conventional filter. Microporous membranes
pores sizes range from 0.01 to 10 μm

7. Homogeneous membranes
Homogeneous membranes are dense
membranes through which molecules
pass by pressure, concentration or
electrical potential gradient. These
membranes are used to separate the
chemical species of similar size and
diffusivity when their concentration
difference significant

8. Electrically charged membrane
These membranes consist of
highly swollen gels which
carry fixed positive or
negative charged. Their
main potential is in
electrodialysis.

9. Asymmetric membranes
Asymmetric membranes consist of two
parts; thin skin layer (0.1-1.0 micron) lay
on highly porous (100-200 micron) thick
substructure. The thin layer acts as a
separator and its separation
characteristics depends on the membrane
material and its pore size. Porous sub layer
has a little impact on separation its main
purpose is to give support to the thin layer

10. Liquid membranes
These membranes utilize
the carrier to transport the
components selectively
like metal ions “at
relatively high rate across
the membrane interface”

11. There are, in fact, two basic types of liquid
membranes, an Emulsion Liquid Membrane (ELM),
and an Immobilized Liquid Membrane (ILM), also
called a Supported Liquid Membrane. An ELM can
be thought of as a bubble inside a bubble inside a
bubble, and so on; the inner most bubble being the
one recieving phase, all the others acting as
separation skins with carriers inside, and anything
outside the bubble being the source phase. In an
ELM setup, there would be huge quantities of these
bubbles, of course, all doing the same thing.

12. An ILM is much simpler to visualize. Pretty much
what you have is some other kind of rigid
membrane, with lots of microscopic pores in it.
Every one of these pores, then, is filled with this
liquid, and in that liquid, you have the organic
liquid and the carrier liquid. What happens then
is that the ILM takes things from one side of the
rigid membrane and carries it to the other side
through this liquid phase. And that, my friends,
is pretty a very brief model of what a LM is.

13. Membrane operations
According to driving force of the operation
it is possible to distinguish:
pressure driven operations
microfiltration
ultrafiltration
nanofiltration
reverse osmosis
gas separation
pervaporation

14. • concentration driven operations
– dialysis
– osmosis
– forward osmosis
• operations in electric potential gradient
– electrodialysis
– membrane electrolysis
– electrophoresis
• operations in temperature gradient
– membrane distillation

15. Widely Used Membrane Processes
There are various types of membrane separation according to the specific industrial needs.
The most widely used processes are,
Reverse Osmosis (RO)
Ultrafiltration (UF)
Micro filtration (MF)
Electro dialysis (ED)
Gas Separation
Pervaporation

16. Applied pressure psi (kPa) Minimum particle Application (type, average removal efficiency %)
Membrane Process
size removed
Particle/turbidity removal (>99%)
Microfiltration 4-70 (30-500) 0.1-3 μm
Bacteria/protozoa removal (>99.99 %)
Particle/turbidity removal (>99 %)
Ultrafiltration 4-70 (30-500) 0.01-0.1 μm
Bacteria/protozoa removal (>99.999 %)
TOC removal (<20%)
Virus removal/(partial credit only)
Turbidity removal (>99%)
Nanofiltration 70-140 (500-1000) 200-400 daltons
Color removal (>98%)
TOC removal (DBP control) (>95%)
Hardness removal (softening) (>90%)
Synthetic organic contaminant (SOC)
removal (500 daltons and up) (0-100%)
Sulfate removal (>97%)
Virus removal (>95%)
Salinity removal (desalination) (>99%)
Hyperfiltration (Reverse 140-700 (1000-5000) 50-200 daltons
Colour and DOC removal
Osmosis) Radionuclide removal (not including radon)
(>97%)
Nitrate removal (85 -95%)
Pesticide/SOC removal (0-100%)
Virus removal (> 95%)
As, Cd, Cr, Pb, F removal (40 to >98%)

17. Reverse Osmosis (RO)
Reverse Osmosis is a high pressure membrane process which
operates at a pressure between 30 -40 bars.This is a reverse of
natural osmosis which works by putting the pressure on the
concentrated side of the membrane which overcome the natural
osmotic pressure.
Reverse Osmosis membranes have the smallest pore size ranging
from approximately 5-15 A° (0.5nm 1.5nm). Extremely small size
of membrane pores only allow to pass through the smallest
organic molecules and unchanged solutes.More than 95-99%
inorganic salts gets rejected by the membrane due to the charge
repulsion established at membrane surface.

18. As compare to basic membrane methods like
microfiltration(MF), ultrafiltrtation(UF)and
Nanofiltratiion(NF) recerse Osmosis can remove the
smallest particles retaining particles smaller than
0.001 microns. Reverse Osmosis can remove the
particles down to the molecular weight of 100.
Rverse Osmosis(RO) can effectively remove sand,
silt, clay, algae, protozoa(5-10 microns)
bacteria(0.4-30 microns), viruses (0.004 -6 microns)
humic acids, organic/inorganic chemicals and most
of the aqueous salts and metal/non-metal ions
including NO3-1, iron and manganese.

19. application
Reverse Osmosis (RO) technique is extensively applied in the following fields
Conversion of sea or brackish water into potable water
To get the ultrapure water for food processing and electronic industries
To get the pharmaceutical grade water
For chemical, pulp and paper industry usable water
Usage in waste treatment

20. Future applications
Reverse Osmosis technique could have a good potential to use in the
future in the following sectors
Municipal and industrial waste treatment applicayions
To process the water for boilers
To de-water feed streams
To process high temperature feed streams etc

21. Micro filtration (MF)
Microfiltration is a low pressure membrane system
which operates at between 0.1 to 0.5 bars. Cross
flow membranes are used and the suspended
particles in the range of 0.05 to 10 microns can be
removed. At present MF membrane technology is
the most widely used membrane technology its
application and sale is more as compare to the rest
of all membrane technologies. MF has too many
small applications, essentially it is a sterile filtration
with pore size 0.1-10.0 microns, this range of pore
size can not let micro-organisms to pass through.

22. applications
Microfiltration technology is widely used
To prepare parenterals and sterile water for pharmaceutical industry
Concentration of fruit juices for food and beverages industry
In chemical industry
In microelectronics industry
For fermentation
Usage in laboratory/analysis

23. Future applications
In future Microfiltration technology has the potential to use in the following
sectors
Biotechnology sector for the concentration of biomass and separation of
soluble products
Diatomaceous earth displacement
During the treatment of non-sewage water to remove intractable particles
from oily fluids and aqueous wastes which contain toxic s and stack gas
To separate solvents from pigments in paints industry

24. Ultrafiltration (UF)
Ultrafiltration is mainly used to separate a mixture which
consists of desirable and undesirable components.
Ultrafiltration process operates between 2-10 bars but in
some cases it goes up to 25-30 bar. Ultrafiltration (UF) can
retain particles from 1000 – 1000 000 molecular weight.
Ultrafiltration system can be based on hollow fibre, spiral
wound or plate and frame membranes.

25. Ultrafiltration can be used to produce many new
products by fractionation of the components like
fat, protein etc and can also be used to improve
the functional properties of the product. One of
the very important applications of ultrafiltration is
its application in recovering and concentrating of
valuable small components like enzymes from
cow milk. Ultrafiltratin technique is also being
used successfully for the isolation of important
components from food processing waste

26. Ultrafltration by using
membranes of polyether
sulfone and plyvinylpyrlidone
can remove the polyphenols
which are responsible for
browning colour and haze
forming in apple juice.

27. Electrodialysis (ED)
Like Reverse Osmosis, ED can remove the
particles smaller than 0.001microns but the
condition is that the particles must be
charged ions. It can not remove non ionic
dissolved species or microbes. Electrodialysis
is an electrochemical process in which ions
pass through an ion selective semipermeable
membrane because of their attraction to the
electrically charged membrane surface.

28. Ions get transported through membrane
from one solution to another under the
influence of electrical potential. ED
system consists of anion and cation
membranes which place in electric field.
The cation selective membrane only let
pass through the cation ions, while the
anion selective membrane will let only
cation ions.

29. applications
ED technique can be applied to for several types of separations like,
To separate and concentrate salts, acids and bases from aqueous solutions
To separate and concentrate monovalent ions from multiple charged componenets
To separate ionic compounds from uncharged molecules
At present ED technique is being widely used
In the production of potable water from sea or brackish water
In electroplating rinse recovery
In desalting of cheese whey
In the production of ultrapurewater etc

30. Future applications
future applications for ED are
To de-ionize water from conductive spacers
To treat radioactive wastewater by using radiation resistant membranes
For the de-acidification of fruit juices
To recover heavy metal
To recover organic acids from salts
To control pH without adding acid or base
To regenerate ion-exchange resins with improved process design
To recover acid from etching baths etc

31. Gas Separation
• Gas separation technology is nearly eleven years old
but has been proven one of the most important
technology. Membranes made up of polymers and
copolymers in the form of flat film or hollow fibre are
being used in gas separation. Gas separation
technology has the advantages of
• Light in weight
• Low labour
• Easy expansion
• Operatable at partial capacity
• Involves low maintenance
• Needs less energy
• Economical so for small sizes

32. applications
Gas separation technology is
being used in the separation and
recovery of hydrogen , natural gas
processing, upgrading of landfill
gas, separation of air, production
of nitrogen, dehydration of air
and recovery of helium etc.

33. Future applications
In future Gas Separation technology has the following potential applications
Air enrichment by N2
Enrichment of air by low level O2
H2 and acid gas separation from hydrocarbons
Recovery of helium
Dehydration of natural gas

34. Pervaporation
Pervaporation is a membrane based
process to separate miscible liquids.
Pervaporation process is very
effective as compare to conventional
techniques to separate the mixtures
of close boiling point or azeotropic
mixtures.

35. • Pervaporation technique works by absorbing
one of the components of the mixture by the
membrane, its diffusion across the membrane
and then evaporation, partial vacuum applied
to the underside of the membrane makes
permeate vapour.

36. • Based on this, hydrophilic membranes are
used for dehydration of alcohols containing
small amounts of water and hydrophobic
membranes are used for removal/recovery of
trace amounts of organics from aqueous
solutions.
• Pervaporation is a very mild process and
hence very effective for separation of those
mixtures which can not survive the harsh
conditions of distillation.

37. applications
• Pervaporation has been used to
• To separate ethanol water mixture
• To recover solvent
• To separate heat sensitive products
• To enrich organic pollutants

38. adavantages
• Pervaporation has certain advantages over
other separation techniques which are
• Its modular membrane design
• It is economical and effective to separate
mixtures of substances with small difference
in boiling points.
• Reduced capital cost as compared to
conventional techniques