it describes what and why treatment is required along with the process and step involves in the treatment of water.

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