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5.2 Freshwater
Pollution
Water Pollution
• Is the introduction of chemical, physical, or
biological agents into water that degrades
the quality of the water and affects the
organisms that depend on it.
Two causes of Pollution
• Industrialization
• Human Population Explosion
Two types of pollution
• Point Pollution
– Pollution that is
discharged from a
single source
• Non-Point Pollution
– Pollution that comes
from many sources
rather than a specific
site
Washing Water
Healthy Water, Healthy People
Water Quality Education guide
Presented by Deb Perryman
Wastewater Treatment
• The Hydrologic Cycle
(The Water Cycle) cleans
and replenishes our
Earth’s water supply.
• Human demand is much
greater than what the
natural cycle can
replenish.
• To accommodate human
consumption, we treat
water before and after it
is used.
First
A large intake pipe draws water
out of a lake, river or groundwater
source into the Treatment Plant.
Flash Mixers
At the plant, the water
goes through a twelve
foot deep Flash
Mixers where alum
and polymer are
added.
Floc
• These clumping
agents make dirt and
bacteria in the water
stick together to form
lumps of material
called floc.
Settling/ Filtering/Clarification
• The floc sinks to the
bottom of the
treatment plant’s
large clarifier pools.
• Remaining dirt
particles are filtered
out of the water by
passing it through
coal, sand, and gravel
filters.
Disinfection
• Chlorine is added to
kill any germs that
remain and make
sure the water stays
pure during delivery
to your home.
Flouride
• Before the clean, pure
water is pumped to
your house, fluoride is
added to it to help
keep your teeth
healthy and cavity
free.
Storage of Clean Water
• The clean water is
stored in huge tanks
all over the service
area to make sure
there is enough
during peak demand
times.
Constant Testing
• Technicians test the
water regularly to
make sure it is always
clean and pure when
it gets to you for
washing, cooking and
drinking.
Water Treatment Process
Once water has been used it
passes through a series of
pipes to a Wastewater
Treatment Plant.
This water again goes through
a series of steps to get
purified.
Gotta love Mike Rowe!
After you Flush!
Primary Waste Treatment
• Filtration, settling, and
skimming procedures
removes 40-50% of
pollutants.
Primary Treatment
• Most raw sewage flows to
the plant by gravity.
• Once at the plant, the
sewage must be pumped
through the facility.
• To accomplish this, the
screw pumps lift the
sewage up so that gravity
may again carry the
sewage on its way.
Screening/ Filtration/ Skimming
• As water comes into the plant,
it receives primary treatment in
the form of fine screens.
• These are used to remove
solids from the wastewater.
Once removed, these solids
are classified as a special
waste that requires permits
and specially licensed trucks to
haul it to a landfill certified for
this waste.
Secondary Wastewater Treatment
• Biological processes
remove 85-90% of
remaining pollutants.
• Microorganisms are
introduced to the water to
consume organic waste
material.
• Solids and
microorganisms are
separated from the
wastewater in Settling
Tanks.
Waste Lagoon
• This wastewater 32 acre
lagoon provides
secondary treatment after
the fine screening.
• In the lagoon, the
organics are dissolved
and suspended matter is
converted by bacteria into
stable end products. The
lagoon is aerated to aid
these bacteria and to
prevent the sewage from
becoming septic.
Lagoon to Plant Pumps
• After the waste makes
the month long journey
from the west end of the
lagoon to the east end,
pumps bring the water
back into the plant. Once
in the plant, flocculants
(polymers) are added to
the water to help settle
the remaining solids.
Tertiary Wastewater Treatment
• Clarification
• Disinfection
• Activated Charcoal
Treatments
• Distillation to remove
Salts
Clarifiers
• These large clarifier tanks
provide the Tertiary
Treatment. Here, the
remaining solids settle to
the bottom with the aid of
Flocculants. While the
treated water flows over
weirs and onto the next
stage of treatment.
Disinfection
• Once the water clears the
clarifiers, chlorine is
injected into the water to
reduce Fecal coliform, as
well as, other potentially
harmful bacteria.
• Once the water is
disinfected, the chlorine is
then neutralized by
adding Sodium bisulfate.
Discharge Pumps
• Now that the sewage
has been cleared of
solid matter, bacteria
and other pollutants,
then again, further
disinfected, the
cleaned water is then
discharged.
Laboratory
• The Wastewater
Treatment Plant
maintains a laboratory
on-site to constantly
monitor both the influent
and effluent to assure
that the water leaves the
plant is safe and
conforms to EPA
requirements.
Water and Wastewater Treatment
• Photos and words used
here by permission from:
• Monroe County Water
Authority, 475 Norris
Drive, Rochester , NY
14610 (585)442-2000
• City of Sterling
Wastewater Treatment,
2400 W. Lynn Blvd.
Sterling, Il 61081
(815)626-8378
Pathogens
• Disease causing organisms, such as
bacteria, viruses and parasitic worms
Biological Magnification
• Each organism stores toxins in their
tissues. As the food chain progresses, the
level of toxic chemicals increases.
Eutrophication
• Slow moving bodies of water contain
excess nutrients and can become
eutrophic
• Artificial Eutrophication- cause by humans
Thermal Pollution
• Excessive amounts of heat are added to a
body of water. Normally it occurs near
power plants and other industries. They
often use natural water systems as part of
their cooling.