Membrane separation technology

Membrane Separation Technology
By
M.Tech Biotechnology

INTRODUCTION
A membrane is a thin semi-permeable barrier which can
be used for the following types of separation:
1. Particle-liquid separation
2. Particle-solute separation
3. Solute-solvent separation
4. Solute-solute separation
Membranes can separate particles and molecules and
over a wide particle size range and molecular weights.

CLASSIFICATION OF MEMBRANE
PROCESSES
Pressure driven membrane based bio separation
processes can be classified into four types based on
the size of the permeable species:
• Microfiltration (MF)
• Ultra filtration (UF)
• Nan filtration (NF)
• Reverse osmosis (RO)

MICROFILTRATION
Microfiltration refers to the separation of suspended material
such as bacteria by using a membrane with pore sizes of 0.1 to
10um
The various applications of microfiltration in biotechnology
include:
1. Cell harvesting from bioreactors
2. Virus removal for pharmaceutical products
3. Clarification of fruit juice and beverages
4. Water purification
5. Air filtration
6. Sterilization of products

ULTRA FILTRATION
UF membranes can retain macromolecular solutes.
Solute retention is mainly determined by solute size.
However, other factors such as solute-solute and solute-
membrane interactions can affect solute retention.
Depending on the protein to be retained, membrane
NMWLs in the range of 1 kD to 1000 kD are used.
Two types of UF are Virus filtration(VF) and High
Performance tangential flow filtration (HPTFF).

VF-This process type is used to separate virus particles
from proteins or from smaller media components, as
either a virus reduction step or a virus harvest step.
VF-membrane NMWL ratings range from 100 k D to
500 k D, or up to 0.05 μ m.
High performance filtration is a high resolution process
where protein-protein separations can be carried out on
the basis of both size and charge, resulting in product
yields and purification factors similar to chromatography
ULTRAFILTRATION

Membrane NMWLs used for HP TFFare in the range
of 10 kD to 300 kD
Common applications: removal and recovery of oils,
surfactants and paints from waste streams, clarification
of wines and juices, and polishing of ultra pure water
for bacteria and particle removal

NANO FILTRATION
Nano filtration (NF) membranes allow salts and
other small molecules to pass through but retain
larger molecules such as peptides, hormones and
sugars.
Pore size is of order of nanometers
Driving force: pressure difference
Common applications: partial softening of feed
water, removal of contaminants from water or acid
streams, and pretreatment for reverse osmosis or
other high purity systems

REVERSE OSMOSIS
• Reverse osmosis (RO) separates salts and small
molecules from low molecular weight
solutes(typically less than 100 daltons) at
relatively high pressures using membranes with
NMWLs of1 k Da or lower.
• Reverse osmosis systems are primarily used to
purify tap water to purities that exceed distilled
water quality.

MEMBRANE MODULES
Flat plate and Frame module
Hollow fibers.
Spiral wounds

FLAT PLATE AND FRAME MODULE
 Plate and frame
or planer modules
consist of a stack
of grooved sheets
which are covered
on both sides by
control membrane

Each membrane covered sheet alternates with a spacer
sheet to form the module stack .
The membrane edges are sealed to prevent the mixing
of the permeate and the feed solution .
The feed solution ,under pressure flows tangentially
along each of the porous sheets as it is directed in
serpentine manner through the stack
The permeate collect in the spacer regions and flows to
the permeate outlet .
Advantage: more surface area per unit volume than flat
sheet membranes
FLAT PLATE AND FRAME MODULE

HOLLOW FIBER
Hollow fiber module are comprised a bundle of membrane
tubes with narrow dia meters, typically in the range of 0.1
to 2.0 nm .
In the hollow fiber module ,the feed stream is pumped in
to the inside of the tube and filtrate passes through the
membrane to the shell side.

SPIRAL WOUND MEMBRANE
Spiral wound module consist of an envelope of
membrane covered sheets and separator sheets
which are wound concentrically around a hollow
core and then inserted in to a canister.
The pressurized feed stream is introduced at one
end of canister and flows tangentially along the
membrane to the exit port of the canister .
The permeate collects in the separator area and
flows to the hollow center where it is removed

APPLICATIONS
The particular advantage of membrane separation
processes is that they operate without heating and
therefore use less energy than conventional thermal
separation processes.
Therefore, cold separation by means of membrane
processes is commonly applied in the food technology,
biotechnology and pharmaceutical industries.
As an artificial kidney to remove toxic substances by
hemo dialysis.

Nano filtration and reverse osmosis membranes are
mainly used for water purification purposes.
Microfiltration and ultra filtration is widely used in
food and beverage processing (beer microfiltration,
apple juice ultra filtration), biotechnological
applications and pharmaceutical industry (antibiotic
production, protein purification), water purification
and wastewater treatment, microelectronics industry,
and others

Membrane separation technology

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