Transcript Water quality - Madison County Schools

Bellringer
What might be some possible downsides to using
icebergs tugged from the poles as a source of
freshwater?
Water to Drink
Notes
Water Quality
• Most of the time, the water you drink, or
the water you interact with, is rarely
composed of only H2O molecules.
• Water quality is a measure of the
substances in water other than the
water molecules.
vs
Water Quality
• The government sets concentration
limits for some substances such as
arsenic, copper, lead, or coliform
bacteria (such as E. coli).
• A concentration is how much there is
of one substance in a certain volume of
another substance. Concentrations are
often measured in parts per million
(ppm).
Water Quality
• The pH of water also affects its quality.
The pH is a measure of how acidic or
alkaline the water is.
• pH is measured on a scale of 1-14, with
1 being the most acidic and 14 being
the most alkaline. Neutral is 7.0 on the
pH scale.
Water Quality
• Calcium and Magnesium are two minerals that
can be found in water as well. These two
minerals are not harmful to humans, therefore
are not regulated the same way.
• The hardness of water is a relative
measurement of the amount of Ca and Mg in
your water.
• Hard water does not form suds easily (meaning
more detergent is needed) and can also form
deposits that can clog pipes and machinery.
Water Quality
• The presence of disease-causing
organisms also affects water quality.
The Escherichia coli bacterium (E.
coli) can be found in human and animal
wastes, and when present in the water
supply, it can indicate that the water has
not been filtered properly.
Treating Drinking
Water
• Water treatment is a way to make water
safe to drink. Water treatment often
takes place in a water treatment plant.
• The first step of drinking-water
treatment from a lake/river is usually
filtration. Filtration is when water is
passed through a series of screens.
The screens do not allow large objects
to pass through.
Treating Drinking
Water
• The second step is coagulation. Coagulation is
when a chemical is added to water to make
particles stick together. The chemical (alum)
causes sticky globs (flocs) to form.
• These globs sink the bottom of a settling basin,
and then the water is filtered again.
• FYI - coagulation is also what your blood does to
form clots and to stop bleeding. Exsanguination
would be a bad thing.
Treating Drinking
Water
• The next step is to add chlorine to the water.
Chlorine is a strong base (alkali) that kills
microorganisms that can cause disease.
• Forced air (aeration) is pumped into the water to
reduce unpleasant odors and tastes.
• Sometimes sodium (Na) or lime will be added to
water to soften hard water, and fluoride (F-) is
added to prevent tooth decay.
Treating Wastewater
• Wastewater and the different kinds of
waste in it are called sewage.
• In most communities, household
wastewater flows into a system of pipes
called sanitary sewers. The sanitary
sewers carry the wastewater to a
wastewater treatment plant.
Treating Wastewater
• Some people treat their sewage using a
septic tank system. A septic tank
system has an underground tank where
bacteria are used to break down
materials in the water as the water
passes through the tank.
• Rid-X
®
is a commercial product that
adds necessary bacteria to a septic
tank system.