This document discusses sedimentation, which is the process by which suspended particles are removed from water by gravity settling. Sedimentation occurs when particles that are denser than the surrounding fluid sink downward while lighter particles float upward. It is used in water treatment plants to filter out unwanted particles. The rate of sedimentation is affected by factors like particle size/density, fluid viscosity, and temperature. Sedimentation tanks allow particles to settle out of water as it slowly flows through, providing some purification and forming a sludge layer at the bottom.

1. SEDIMENTATION
Mrs. Praveen Garg
VITS College, Satna

2. Introduction
• Sedimentation, or clarification, is the processes of
letting suspended material settle by gravity. Suspended
material may be particles, such as clay or silts,
originally present in the source water.
• For example, sand and silt can be carried in suspension
in river water and on reaching the sea bed deposited
by sedimentation.
• The purpose of sedimentation is to enhance the
filtration process by removing particulates.
Sedimentation is the process by which suspended
particles are removed from the water by means of
gravity or separation.

4. Example of sedimentation
• Tea leaves settling down on cup of tea.
• Soil settling in pond water.
• Water treatment plants use the method
of sedimentation to filter out unwanted particles from
unclean water.
• Decantation is the separation process of two immiscible
liquid mixture or solid and liquid mixtures.

5. Sedimentation principle
• In a solution, particles whose density is higher than that
of the solvent sink (sediment), and particles that are
lighter than it float to the top. The greater the difference
in density, the faster they move.
• Sedimentation may depend to objects of various sizes,
ranging from large rocks in flowing water, to suspensions
of dust and pollen particles, to cellular suspensions,
to solutions of single molecules such
as proteins and peptides.
• Even small molecules supply a sufficiently strong force
to produce significant sedimentation.

6. Types of Sedimentation
• Type 1 – Dilutes, non-flocculent, free-settling (every
particle settles independently.)
• Type 2 – Dilute, flocculent (particles can flocculate as
they settle).
• Type 3 – Concentrated suspensions, zone settling,
hindered settling (sludge thickening).

7. • There are four types: lithogenous, hydrogenous,
biogenous and cosmogenous.
• Lithogenous sediments come from land via rivers, ice,
wind and other processes.
• Biogenous sediments come from organisms like
plankton when their exoskeletons break down.
• Hydrogenous sediments come from chemical reactions
in the water.
• Cosmogenous sediments come from outer space and
have extraterrestrial sources, such as the remains from
the impact of large bodies of space material like comets
and asteroids. This type of sediment is rarely found by
scientists and is the most insignificantly important one.

8. Factors affecting Sedimentation
• Particle size, density and concentration, and fluid viscosity,
other factors affect the sedimentation rate.
• These include particle shape and orientation, convection
currents in the surrounding fluid, and chemical
pretreatment of the feed suspension.
• Alum increases the rate of sedimentation because alum
being an external agent causes the particles present in the
container to colloid together and form heavier particles, as
heavier particles sink in water these particles settle down
therefore increasing the speed of sedimentation.
• There is a general increase in the rate
of sedimentation with temperature. A 20°C rise
in temperature typically doubles the rate of sedimentation.

9. Water treatment Process
• The sedimentation process is used to reduce particle
concentration in the water.
• The advantage of sedimentation is that it minimizes the
need for coagulation and flocculation.
• Typically, chemicals are needed for coagulation and
flocculation, but improved sedimentation controls the
need for additional chemicals.

11. Ways of Separation
• Sedimentation:
• Distillation: separation by boiling point differences. ...
• Floatation: separation of solids by density different. ...
• Chromatography: separation by inner molecular
attractions.
• Magnetism:
• Filtration:
• Extraction:
• Crystallization:
• Mechanical Separation:

12. Functions
• A sedimentation tank allows suspended particles to
settle out of water or wastewater as it flows slowly
through the tank, thereby providing some degree of
purification.
• A layer of accumulated solids, called sludge, forms at
the bottom of the tank and is periodically removed.
• The sedimentation analysis is based on
stokes law according to which the velocity at which the
grains settles down depend on shape, size, weight of
grain.

13. Thank You