The document describes the process of drinking water treatment, which enhances water quality for various uses by removing contaminants through chemical, physical, and biological methods. Key processes include screening, coagulation, sedimentation, filtration, and disinfection, utilizing various chemicals to promote the clumping of particles and ensuring the removal of pathogens. Different types of filters and their respective methods are also detailed, highlighting the complexities and operational requirements of the treatment systems.

1. Drinking Water Treatment
Environmental Engineering

2. Introduction
• It is the process of improving the quality of water to make
it appropriate for use.
• The water after treatment can be used for for drinking ,
industrial water supply, river flow maintenance, etc.
• Water treatment removes the contaminant and undesired
component or reducing the concentration so that the
water becomes fit to use.

3. Process:
• Chemical
• Physical
• Physio-chemical
• Bio-chemical

4. Chemical
• Pre-chlorination for algae control
• Aeration along with pre-
chlorination for removal of
dissolved iron when present with
small amounts relatively of
manganese.
• Disinfection for killing pathogens,
using chlorine, ozone and ultra-
violet light.

5. • Sedminantaion process
• Filtration process
• Dissolve air flotation
• Coagulation for
flocculation.
• Coagulant aids to improve
coagulation and for more
robust floc formation.
Physio-chemicalPhysical

6. Biological
• Slow sand filtration using a
biofilm to metabolize
organic matter.
Water treatment

7. Chemical Addition
• chemical /coagulant are used inorder to make the
suspended particle that are floating in the water clump
together to form a heavier and larger gelantinous particle
• In this process, a chemical is added that reacts with the
natural alkalinity in solution to form an insoluble
precipitate.
• some of the chemical used are: aluminum sulfate, ferrous
sulfate, ferric chloride, sodium aluminate, activated silica

8. STEP/METHOD USED

9. Step in treatment

10. Screening
• first unit operation carried out
inorder to retain solid found in
water mostly by using the large
metal screen or bar screen
which is place in intake.
• Large items are trapped on the
screen as the
• water passes through it. These
screens must routinely be raked
or cleaned off.

11. Coagulation and Flocculation
• Coagulation and flocculation are
used to separate the suspended
solids portion from the water.
• Suspended particles vary in source,
charge, particle size, shape, and
density.
• The process of adding a chemical to
cause the suspended material to
“clump” into larger particles is called
flocculation or coagulation.

13. • During sedimentation, floc settles to the bottom of the
water supply, due to its weight. This settling process is
called sedimentation.
Sedimentation

14. Filtration
• After floc settlement on bottom
of W/s, clear water on top pass
through filters of varying
compositions (sand, gravel,
and charcoal) and pore sizes,
inorder to remove dissolved
particles such as dust,
parasites, bacteria, viruses &
chemicals.

15. Type of filter
• Slow sand filter
 1 to 2 metres deep
loading rate of 200 to 400
litres per hour per square
metre
Slow sand filters use
biological processes to
clean the water, and are
non-pressurized systems

16. • Rapid sand filter
 multi-stage treatment
systems
 complex and expensive to
operate and maintain
use of flocculation
chemicals—typically alum
rate of filtration 80 to 120
Lpm/ m2 of filter bed area or
4.8 to 7.2 m/ h.

17. • Pressure Filtration
It consists of a round container
with filter materials.
 On top there is a cover with hose
connections and the operation.
 Water is pressed through the
filters under pressure of the pond
pump.
With the help of bacteria the filter
removes the dirt particles from the
water.

18. Disinfection
• it involves the addition of
chemicals in order to kill or
reduce the number of
pathogenic organisms