clarification and filtration.pptx

PRESENTED BY:
Miss.Harshada R. Bafna.
M. Pharmacy.(Q.A.)

1. Introduction
2. Factors affecting rate of filtration
3. Filter media
4. Filter aids
5. Filtration equipments
7/29/2022 Filtration and clarification (HRB) 2

Definition
• Filtration: It may be define as a process of separation of
solids from a fluid by passing the same through a porous
medium that retains the solids but allows the fluid to pass
through.
• Clarification: When solid are present in very low
concentration, i.e., not exceeding 1.0% w/v, the process of
its separation from liquid is called clarification.
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7/29/2022 Filtration and clarification (HRB)

Introduction
 Ultra-Filtration: Separation of
intermicellar liquid from solid by the use of
pressure on a semi permeable membrane.
 Cake Filtration: If recovery of solid is
desired, the process is called cake filtration.

Terms used in filtration
Slurry
• Suspension to
be filtered
Filter
medium
• Porous medium
used to retain
solid
Filter
cake
• Accumulated
solids on the filter
Filtrate • Clear liquid passing
through the filter
5

Theories of filtration

Darcy’s Equation
• Poiseullie's law assumes that the capillaries found in the
filter are highly irregular and non-uniform.
• Therefore, if the length of capillary is taken as the
thickness of bed, a correction factor for radius is applied so
that the rate is closely approximated and simplified.
• The factors influencing the rate of filtration has been
incorporated into an equation by Darcy, which is:
• Where, K = permeability coefficient of cake, m2
A = surface area of porous bed (filter medium),
m2 Other terms are same as previous equation
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• K depends on characteristics of cake, such as porosity,
specific surface area and compressibility
• Permeability may be defined quantitatively as the flow rate
of a liquid of unit viscosity across a unit area of cake
having unit thickness under a pressure gradient of unity.
• This equation is valid for liquids flowing through sand,
glass beds and various porous media.
• This model is applied to filter beds or cakes and other
types of depth filter.
• This equation is further modified by including
characteristics of K by Kozeny-Carman.
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1. Area of filter surface.
2. Particle size of cake solids.
3. Pore size of filter media.
4. The resistant of the filter cake and filter
media.
5. Viscosity of liquid to be filter.
6. Temperature.
7. Pressure difference across the filter.
8. Nature of solid material.

“The surface upon which solids are deposited in a filter
is called the Filter medium”.
PROPERTIES OF IDEAL FILTER MEDIA:
1. Chemically inert.
2. High retention power.
3. Sufficient mechanical strength.
4. Absorbs negligible amount of material.
5. Resistant to the corrosive action of liquid.
Selection of filter media depends on followings:
1. Size of particle to be filtered.
2. Amount of liquid to be filtered.
3. Nature of product to be filtered.
4. Purpose of filter.
7/29/2022
10
Filtration and clarification (HRB)

 Filter paper:
Filter paper is a common filter
medium since it offers controlled
porosity, limited absorption
characteristic, and low cost
• It has different grades and qualities
different pore size such as coarse
medium and fine.
Disadvantages:
• They shed very fine particle to the
filtrate.
• Absorb small quantity of liquid.

Cotton Wool:
• Commonly used.
• Small tough of cotton
wool placed in the neck
of funnel.
Glass wool:
• Use for filtering highly
corrosive chemicals.
• May contaminate the
filtrate with glass fibers

Asbestos:
• Also used for filtering
the corrosive liquid.
• They impart alkalinity
to the filtrate.
• Alkaloids may get
absorbed.
• May contaminate the
filtrate.

 Membrane Filter:
• These are very common
among the ultra filtration
methods.
• Made up of cellulose,
Polyvinylchloride, Nylon
and other cellulose
derivatives.
• They rare very fine
having a very vide range
of pore size from 8µ
down to 0.22µ.

Craft Paper:
• Mainly used in plate and frame filters.
• They offer controlled porosity
• Limited absorption.
• Quite cheap.
Sintered Glass:
• Consist of Pyrex glass powder.
• Used for filtering parenteral preparations.
• Useful for filtering the corrosive liquid and oxidizing agent.
• Don’t shed particles.
• Don’t absorbs any liquid.
• Can be easily washed.

“The substances which when added to the liquid to be
filtered, reduce the resistance of the filter cake and
increase the filtration”.
 Properties of Filter Aids:
• Chemically inert
• Low specific gravity
• Insoluble in liquids
• Form a porous cake
• Free from impurities
• Suitable particle size with irregular shape
• Able to remain suspended in liquids
• Free from moisture

Materials Chemical
composition
Advantages Disadvantages
Diatomaceous earth Silica Wide size range Slightly soluble in
acid and alkalies
Perlite Silica
+Aluminosilicate
Wide size range More soluble
Asbestose Aluminosilicate Very good retaintion
on coarse screen
More soluble
Cellulose Cellulose Chemically inert Expensive
Carbon Carbon Non reactive with
strong alkalies
Expensive

ASBESTOSE CELLULOSE CARBON
DIATOMACEOUS EARTH PERLITE

Selection of method and equipment required
for filtration of a liquid depends on nature
of the material and quantity to be filtered as
well as the object of the operation.

Construction
• The Filter press is made of two types of units, plate and frames.
• Usually made of aluminium alloy.
• Frame
 It contains a open space inside wherein the slurry reservoir is
maintained for filtration and an inlet to receive the slurry.
 It is indicated by two dots in description.
20
Slurry inlet
Handle to rest on rod
Plate and frame filter press

• Frames of different thickness are available.
• It is selected based on the thickness of cake formed during filtration.
• Optimum thickness of frame should be chosen.
• Plate
 The plate has a studded or grooved surface to support the filter cloth
and an outlet.
 It is indicated by one dot in description.
21
Through channel
Filtrate outlet

Diagram
22

Working
• Working can be divided into two steps-
1. Filtration operation
2. Washing of cake (if desirable)
• Filtration operation
23
Frame- marked by 2 dots
Plate – marked by 1 dot
Plate and frame filter press, principle of filtration operation

Advantages:
• Construction is very simple.
• Used for coarse to fine filtration.
• Operation and maintenance is easy.
• Filter cloth can be easily replaced.
Disadvantages:
• Not economical for filtration of small quantities
• Leakage between the plates may take place
• Suitable when the slurry contain less than 5%
solids.

Filter leaf
Construction:
• The leaf filter is consisting of a frame enclosing a drainage screen or
grooved plate.
• The frame may be any shape circular, square or rectangular.
• The whole unite being covered with filter cloth.
• The outlet for the filtrate connects to the inside of the frame through
suction.
25

Diagram
26

Working and uses
Working:
Use:
• Use for the filtration of slurry which do not contain high solid content,
about 5%, i.e. dilute suspensions.
27
The filter leaf
is immersed
in the slurry
Vacuum
system is
connected to
the outlet
The slurry
passes
through the
filter cloth
Finally filtrate
enters the
drainage canal
and goes
through the
outlet into
receiver
Air is passed
to flow in
reverse
direction
which
facilitates
removal of
cake

Advantages:
• Liquid can be filtered form any vessel.
• Filter cake can be removed simply by washing or
blowing air.
• It is very economical.
Disadvantage:
• It is not effective when solid content in the liquid is
more than 5%.

Metafilter
Construction
• Metafilter consists of a series of metal rings.
• These are threaded so that a channel is formed on the edges.
• It contains a grooved drainage column on which a series of metal rings
are packed.
• These rings are usually made up of stainless steel and have dimensions
of about 15.0 mm internal diameter and 22.0 mm external diameter.
• Each metal ring has a number of semicircular projections (0.8 mm in
thickness) on one side of surface.
• The projections are arranged as a nest to form channels on the edges.
• These rings are tightened on the drainage column with a nut.
• Metafilters are also known as edge filters.
29

Diagram
30

Working
Filters are placed in a
vessel
Slurry is pumped
under pressure or
occasionally by
applying reduced
pressure to the outlet
side
Slurry passes through
the channels formed
on the edges between
the rings
The clear liquid rises
up and collected from
the outlet into
receiver
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 For separation of fine particles, a bed of suitable materials such
kieselguhr is first built up.
 The pack of rings serves essentially as a base on which the true filter
medium is supported.

Uses
• Metafilters can be used for-
 Clarification of syrups
 Filtration of injection solutions
 Clarification of insulin liquors
 Filtration of viscous liquids can be achieved by applying pressure.
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Advantages
• Can be used under high pressures, without any danger of bursting the
filter medium.
• Running cost are low, as separate filter medium is not used.
• Can be constructed from a material that can provide excellent
resistance to corrosion and avoid contamination of sensitive products.
• It is extremely versatile filter because fine as well as large both type of
particles can be separated.
• Removal of cake can be carried out by simply back- flushing with
water.
• Change over from one batch to another or one product to another is
easy.
• Sterile products can be handled.
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clarification and filtration.pptx

clarification and filtration.pptx

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