This document summarizes clarification, which is the separation of solids from fluids or fluids from other fluids. It discusses various clarification processes like filtration and centrifugation. Filtration methods are classified as solid/fluid, solid/gas, or fluid/fluid. Applications in pharmaceutical processing include improving product appearance and removing contaminants. Factors affecting the rate of filtration are also summarized.

1. Clarification
A
Presentation
on:
Asif Pappu
ACCE,NSTU

2. Clarification:
Separation of solid from a fluid or a fluid from another fluid.
Clarification process is mainly done by
 Filtration
 Centrifugation.
Main reasons:
1. To remove unwanted solid particles from liquid
2. To collect the solid as the product itself.
Classification of filtration
1. Solid/fluid filtration
2. Solid/gas filtration
3. Fluid/fluid filtration

3. Solid/fluid filtration
The separation of an insoluble solid from a fluid by means of a porous medium.
Solid/fluid filtration subdivided into two types,
• Solid/liquid filtration
• Solid/gas filtration.
Applications of solid/liquid filtration in pharmaceutical processing:
• Improvement of the appearance of solutions, mouthwashes etc. for clarifying product.
• Removal of potential irritants
• Production of water of appropriate quality for pharmaceutical production
• Recovery of desired solid material from a suspension or slurry
• Sterilization of liquid or semi-solid products
• Detection of microorganisms present in liquids

4. Solid/gas filtration.
Two main applications of solid/gas filtration in pharmaceutical
processing.
• Removal of suspended solid material from air
• To remove particulate matter generated during a manufacturing
operation from the process air in order to prevent the material being
vented to the atmosphere.

5. Fluid/fluid filtration
Flavoring oils are added to liquid preparations in the form of a spirit, i.e. dissolved in
alcohol. When these spirits are added to aqueous-based formulations some of the oil
may come out of solution, giving the product a degree of turbidity. Removal of the oil
droplets by passing them through an appropriate filter (a liquid/liquid filtration process)
is used to produce the desired product appearance.
Compressed air is used in a number of pharmaceutical processes, e.g. film-coating
spray guns bottle-cleaning equipment and fluid energy mills. Before use, the
compressed air needs to be filtered to ensure that any entrained oil or water droplets
are removed. This is an example of a fluid/gas filtration process.

6. Factors affecting Rate of Filtration
The chosen filtration process must remove the contaminants from the
product
• At an acceptably fast rate
• Economically

7. Darcy’s Equation
• All the factors that affect the rate of filtration is compiled into one equation by Henry Darcy
(1830)
• The equation represents rate of flow through the capillaries of the filter medium and the filter
cake.
• V = Volume of filtrate
• t = Time of filtration
• A = Area of filter medium
• ∆𝑃 = Pressure drop across filter medium and filter cake
• 𝜇 = Viscosity of the filtrate
K is a constant representing the • l = thickness of the cake resistance of the filter
medium and filter

8. Mechanism of filtration:

9. Methods used to increase the rate of filtration:

10. Applications:
Pharmaceutical industry :
Enzymes, amino acids, antibiotics, pharmaceutical intermediates, bulk drugs, medicine, blood products,
antibiotics calcium phytate, Chinese inositol, growth derived sand, organic phosphorus, glucoamylase.
Chemical industry:
Dyes, pesticides, silicic acid, glycerin, white carbon, busy, sodium carbonate, additives, basic chemicals, chemical filler,
pigment, white alumina, manganese, caustic soda, soda ash, alkali salts mud, saponin, graphite.
Food industry :
Wine filter press, yeast, fruit juice filter press, edible oil, vegetable oil, soy sauce, sugar mills, rice wine,
white wine, fruit juices, soft drinks, beer, yeast, citric acid, vegetable protein, plant density sweetener,
glucose.
Environmental Engineering :
Chemical waste water, wastewater filter press, mining wastewater filter press, domestic wastewater,
waste water, waste steel, waste removal, leather waste water, ports silt, mud, salt mud wastewater.

11. ADVANTAGE
 Construction of the filter press is simple
and variety of materials can be used.
 It is provided a large filtering area in the
relatively small floor space.
 The sturdy construction permits the use
of the considerable pressure difference.
 Efficient washing of the cake is possible.
 It produces dry cake in the form of slab.
DISADVANTAGE
 It is a batch filter so there is a good deal of
down time which is non productive.
 The filter press is an expensive filter.
 Operation is critical as the frames should
be full other wise the washing is inefficient
and the cake is difficult to remove.
 The filter press is used for the slurries
containing less than 5% solids.

12. Centrifugation:
Centrifugation is a technique of separating substances which involves
the application of centrifugal force.
The particles are separated from a solution according to their size,
shape, density, viscosity of the medium and rotor speed.
Types of centrifugation
1. Low speed centrifuge
2. High speed centrifuge
3. Ultracentrifuges
4. Analytical centrifuge
5. Micro centrifuge

13. Principle of centrifugation:
Particles having a size above 5m sediment at the bottom due to gravitation force and
separated by filtration. If the size of particles is less than 5m they undergo Brownian motion.
For that they are separated by centrifugation.
Considering a body of mass m rotating in a circular path of radius r at a velocity of v. The
force acting on the body in a radial direction is given by:
F = mv2/r
The gravitational force acting upon the same body G = mg
The centrifugal effect is the ratio of the centrifugal force and gravitational forces so that
C= F/G = m𝑣2/mgr = 𝑣2/gr (3)
Since, v = 2 r n where n = speed of rotation (r.p.m.)
C= F/G = (2πrn)2/ gr = 4𝜋2
𝑛2
𝑟2
=
2𝜋2
𝑔𝐷𝑛2 = 𝑘D𝑛2
; here k=
22
𝑔
= constant (4)

15. Thank you!