Filtration is the process of separating solids from fluids by passing the fluid through a porous medium that retains the solids. There are different types of filtration including surface filtration using screens or sieves, and depth filtration where particles are retained within the tortuous paths of the medium. Filtration has various applications in industries like pharmaceuticals and wastewater treatment. Mechanical screening is used to separate materials into grades by particle size and involves vibrating screens to facilitate separation based on factors like vibration, density, and particle shape.

2. Filtration and Screening
Instructor:
Mam.Hifza Sajid
Department:
FOOD SCIENCE AND TECHNOLOGY

3. Muzammal Siddique 16-uglc-625
Muhammad Ammar 16-uglc-632
Muhammad Usman 16-uglc-630
Asad Ali 16-uglc-624

5.  History
 Definition
 Terms used in filtration
 Process of filtration
 Types of filtration
 Applications of filtration
 Advantages
 Disadvantages

6. After 500 BC, Hippocrates discovered the healing
powers of water. He invented the practice of sieving
water, and obtained the first bag filter, which was called
the 'Hippocratic sleeve'. The main purpose of the bag
was to trap sediments that caused bad tastes or odours.
In 300-200 BC, Rome built its first aqueducts.

7. 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.

9.  Pores of filter medium are smaller than size of
particles to be separate.
 Filter medium (filter paper) is placed on a support
(mesh)
 Slurry is placed over the filter medium
 Due to pressure difference across the filter, fluid
flows through the filter medium
 Gravity is acting over the liquid medium
 So solids are trapped on the surface of the filter
medium

10.  Surface/screen filtration:
 It is a screening action by which pores or holes of
medium prevent the passage of solids.
 Mechanism involved: straining and impingement
 For this, plates with holes or woven sieves are used.
 Efficacy is defined in terms of mean or maximum
pore size.

11.  Depth filtration:
 In this slurry penetrates to a point where the diameter
of solid particles is greater than that of the tortuous
void or channel.
 Mechanism: Entanglement
 The solids are retained with a gradient density
structure by physical restriction or by adsorption
properties of medium.

13.  Production of sterile products
 Production of bulk drugs
 Production of liquid dosage
 Effluents and waste water treatment

14.  It is very easy and straightforward to use.
 Water filtration is cost effective, and it does not
require a lot of money to maintain.
 The odour and taste of the water will improve. Walter
filtration also gets rid of chlorine in the hard water.
 The method also ensures that harmful toxins are
removed from the hard water.

15.  Not all germs and contaminants are removed from
filtered water. When the process is taking place very,
small particles can pass through the membranes used to
perform water filtering.
 Thorough cleaning and care of the equipment is very vital
so that they can carry out the water softening process
without any hitch whatsoever.
 All the cartridges must be disposed of after the water
softening process. These cartridges contain harmful toxins
that were purified from the hard water. If they are thrown
anyhow they might end up being pollutants to the
environment.

17.  Definition
 Applications
 Process
 Physical principles
 Types of mechanical screening

18. Mechanical screening, often just called screening, is the
practice of taking granulated ore material and separating
it into multiple grades by particle size.
This practice occurs in a variety of industries such as
mining and mineral processing, agriculture,
pharmaceutical, food, plastics, and recycling.

19. The mining and mineral processing industry uses
screening for a variety of processing applications. For
example, after mining the minerals, the material is
transported to a primary crusher. Before crushing large
boulder are scalped on a shaker with 0.25 in (6.4 mm)
thick shielding screening. Further down stream after
crushing the material can pass through screens with
openings or slots that continue to become smaller.
Finally, screening is used to make a final separation to
produce saleable products based on a grade or a size
range.

20. A screening machine consist of a drive that induces
vibration, a screen media that causes particle separation,
and a deck which holds the screen media and the drive
and is the mode of transport for the vibration.
There are physical factors that makes screening practical.
For example, vibration, g force, bed density, and
material shape all facilitate the rate or cut. Electrostatic
forces can also hinder screening efficiency in way of
water attraction causing sticking or plugging, or very
dry material generate a charge that causes it to attract to
the screen itself.

21. As with any industrial process there is a group of terms
that identify and define what screening is. Terms like
blinding, contamination, frequency, amplitude, and
others describe the basic characteristics of screening, and
those characteristics in turn shape the overall method of
dry or wet screening.
In addition, the way a deck is vibrated differentiates
screens. Different types of motion have their advantages
and disadvantages. In addition media types also have
their different properties that lead to advantages and
disadvantages.
Finally, there are issues and problems associated with
screening. Screen tearing, contamination, blinding, and
dampening all affect screening efficiency.

22. Vibration: either sinusoidal vibration or gyratory vibration.
Sinusoidal Vibration occurs at an angled plane relative to the
horizontal. The vibration is in a wave pattern determined by
frequency and amplitude.
Gyratory Vibration occurs at near level plane at low angles in a
reciprocating side to side motion.
Gravity : This physical interaction is after material is thrown
from the screen causing it to fall to a lower level. Gravity also
pulls the particles through the screen media.
Density : The density of the material relates to material
stratification.
Electrostatic Force - This force applies to screening when
particles are extremely dry or is wet.

23. There are a number of types of mechanical
screening equipment that cause segregation.
These types are based on the motion of the
machine through its motor drive.

24. Circle-throw vibrating equipment :
This type of equipment has an eccentric shaft that
causes the frame of the shaker to lurch at a given angle.
This lurching action literally throws the material
forward and up. As the machine returns to its base state
the material falls by gravity to physically lower level.
This type of screening is used also in mining operations
for large material with sizes that range from six inches to
+20 mesh.

25. High frequency vibrating equipment :
This type of equipment drives the screen cloth only.
Unlike above the frame of the equipment is fixed and
only the screen vibrates. However, this equipment is
similar to the above such that it still throws material off
of it and allows the particles to cascade down the screen
cloth. These screens are for sizes smaller than 1/8 of an
inch to +150 mesh.

26. Gyratory equipment :
This type of equipment differs from the above two such
that the machine gyrates in a circular motion at a near
level plane at low angles. The drive is an eccentric gear
box or eccentric weights.