Transcript WATER TREATMENT PROCESSES

Water Treatment
Physical Treatments
Chemical Treatments
Obj 3.10 Physical Treatments
screening
 aeration
 flocculation
 sedimentation
 filtration

Physical - Screening
removes large objects (fish, paper,
sticks, plants,...) that would clog pipes
in treatment plant
 water passed through a series of
moving screens.

Physical - Aeration
increases dissolved oxygen in the water
prior to treatment … oxygen is a natural
purifier
 cascading water over falls; spraying
water through the air; bubbling oxygen
through water

Physical -Flocculation
to remove suspended and dissolved
solids from the water
 slow stirring of water with a coagulant
produces “floc” which is heavier than
the water

Physical - Sedimentation
first attempt to reduce the turbidity of
water
 water is pumped into settling tanks to
allow the floc and other solids to settle
out of water; clear water is skimmed off
top

Physical - Filtration
removal of micro-fine solids and microorganisms
 water is filtered under pressure through
gravel-sand-anthracite filters; filters can
also be man-made membranes

Obj 3.11 Chemical Treatments
softening
 coagulation
 disinfection
 fluoridation
 ammoniation

Chemical - Softening
removal of excess calcium and
magnesium from the water supply
 addition of lime and soda ash causes
the Ca and Mg to precipitate out of
solution

Chemical - Coagulation
use of a chemical agent to remove
suspended and dissolved solids
 addition of aluminum sulphate causes
solids to “floc” together and later settle
to the bottom; process is paired with
flocculation

Chemical - Disinfection
to destroy micro-organisms and other
pathogens not captured by the filtration
process
 chlorination, ozonation, or irradiation
with UV light kills microscopic
organisms

Chemical - Fluoridation
To ensure some fluoride content for
public dental health; fluoride hardens
teeth enamel against dental caries
 addition of fluorine compounds in very
small concentrations (1 mg/L)

Chemical - Ammoniation
addition of ammonia prior to
distribution to the consumer
 keeps chlorine from dissipating in
system; some chlorine must be present
even after leaving the water treatment
plant

Obj 3.12 Water Sources
surface water
 ground water
 each source will have different physical
and chemical characteristics and thus
require different treatment processes

Ground Water
low in dissolved oxygen
 high in dissolved minerals
 low turbidity
 no large debris
 little biological activity
 cold or warm depending on location
 may be toxins, poisons, etc.

Surface Water
high in dissolved oxygen
 low in dissolved minerals
 high turbidity
 large debris
 high biological activity
 cold or warm depending on location
 may be toxins, poisons, etc.

Obj 3.13 Typical Surface
Water Treatment
screening
 coagulation & flocculation
 sedimentation
 filtration
 disinfection
 fluoridation
 ammoniation

Obj 3.13 Typical Ground
Water Treatment
aeration
 softening
 filtration
 disinfection
 fluoridation
 ammoniation
