Properties of water Water is less dense as a solid than a
liquid. Only naturally occurring compound that does that. Has an
unusually high boiling point for a liquid
Slide 5
Properties of water Has a very high specific heat value (amount
of energy needed to raise the temperature 1 o C). 4.2 J/g o C Water
is known as The Universal Solvent. Best solvent, able to dissolve
almost anything!
Slide 6
In a water molecule two hydrogen atoms form bonds with one
oxygen atom. Gives water more structure than other liquids The
region around oxygen has a partial negative charge. The region near
the two hydrogen atoms has a partial positive charge. A water
molecule is a molecule with opposite ends of the molecule with
opposite charges. Properties of water
Slide 7
Cohesion among water molecules plays a key role in the
transport of water against gravity in plants Adhesion, clinging of
one substance to another, contributes too, as water adheres to the
wall of the vessels. Properties of water Bonds in H 2 O hold the
substance together, a phenomenon called cohesion
Slide 8
Surface tension, a measure of the force necessary to stretch or
break the surface of a liquid, is related to cohesion. Water has a
greater surface tension than most other liquids because bonds among
surface water molecules resist stretching or breaking the surface.
Water behaves as if covered by an invisible film. Some animals can
stand, walk, or run on water without breaking the surface.
Properties of water
Slide 9
Water as a Mixture A mixture that has the same composition
throughout the substance is called a homogeneous mixture. A
Solution is a mixture that has the solute (the stuff that
dissolves) and the solvent (the stuff that does the dissolving).
Examples: Kool-Aid, Salt water, Orange Juice, etc
Slide 10
Acids & Bases To measure the ________ of an acid or base,
we look at that substances __________ to produce _________ ions in
solution. strength potentialhydrogen We call this the ___ scale
pH
Slide 11
The pH Scale A substance with a pH less than 7 is an ______.
acid A substance with a pH greater than 7 is a ______. base A
substance with a pH equal to 7 is considered ________. neutral
Slide 12
pH of Common Substances Timberlake, Chemistry 7 th Edition,
page 335 1.0 M HCl 0 gastric juice 1.6 vinegar 2.8 carbonated
beverage 3.0 orange 3.5 apple juice 3.8 tomato 4.2 lemon juice 2.2
coffee 5.0 bread 5.5 soil 5.5 potato 5.8 urine 6.0 milk 6.4 water
(pure) 7.0 drinking water 7.2 blood 7.4 detergents 8.0 - 9.0 bile
8.0 seawater 8.5 milk of magnesia 10.5 ammonia 11.0 bleach 12.0 1.0
M NaOH (lye) 14.0 8 910 111214 13 34 5 6 2 1 70 acidic neutral
basic [H + ] = [OH - ]
Slide 13
Water Cycle Water covers about three-quarters of Earth's
surface and is a necessary substance for life. During their
constant cycling between land, the oceans, and the atmosphere,
water molecules pass repeatedly through solid, liquid, and gaseous
phases (ice, liquid water, and water vapor), but the total supply
remains fairly constant.
Slide 14
Slide 15
Evapotransporation Heat energy from the sun causes water in
puddles, streams, rivers, seas or lakes to change from a liquid to
a water vapor. This is called evaporation. Evapotranspiration water
that is transferred into the atmosphere from evaporation,
transpiration (from plants), and perspiration (from animals).
Slide 16
Slide 17
Condensation Water vapor collects in clouds. As the clouds cool
the water vapor condenses into water drops. This is called
condensation. These drops fall to the earth as rain, snow or
hail.
Slide 18
Precipitation Water falls to the earth from clouds. Mainly as
rain, but sometimes as snow and hail. This is called
precipitation.
Slide 19
Freshwater accounts for only some 6 percent of the world's
water supply, but is essential for human uses such as drinking,
agriculture, manufacturing, and sanitation. Large reserves are
groundwater (4 percent) and icecaps and glaciers (about 2 percent).
All other water bodies together accounting for a fraction of 1
percent. So, almost 2/3 of global freshwater is found underground
and almost 1/3 is frozen! Freshwater Resources
Slide 20
Water Use in the World and U.S. The world uses 338,000,000,000
gallons of water per day. The average U.S. person uses 1400
gal/day. (2 x that of a European person) This statistic includes
direct and indirect water use. Humans only require 1 gal/day to
survive. A person can only go about a week without water. However a
person can go 30 days without food.
Slide 21
Average water requirements Item Gallons used 1 pound of cotton
2,000 1 pound of grain-fed beef800 1 loaf of bread 150 1 car
100,000 1 kilowatt hour of electricity 25 1 pound of rubber 100 1
pound of steel 25 1 gallon of gasoline 10 1 load of laundry 60 1
ten-minute shower 25-50
Slide 22
Drinking Water in the US The United States has one of the
safest water supplies in the world. In recent years, microbial
contamination of the water supply has led to highly publicized
outbreaks of disease, causing illnesses. How safe is our water?
Where do these infectious microbes come from? How is water treated
now and whats being done to make it even safer?
Slide 23
Drinking Water Treatment Water treatment transforms raw surface
and groundwater into safe drinking water. Water treatment involves
two major processes: physical removal of solids and chemical
disinfection. COAGULATION: WATER TOWARDS SEDIMENTATION Coagulation
removes dirt and other particles suspended in water. alum and other
chemicals are added to water to form tiny sticky particles called
floc which attract the dirt particles. The combined weight of the
dirt and the alums (floc) becomes heavy enough to sink to the
bottom during sedimentation.
Slide 24
Water Treatment Raw Water Storage Mixing Flocculation
Sedimentation Filtration Clear Well Distribution Ozonation
Coagulant, pH Adjustment Disinfectant (Cl 2, NaOCl)
Slide 25
Slide 26
Slide 27
Water Treatment FILTRATION, DISINFECTION & STORAGE:
FILTRATION: The water passes through filters, some made of layers
of sand, and charcoal that help remove smaller particles.
DISINFECTION: A small amount of chlorine is added or some other
disinfection method is used to kill microorganisms that may be in
the water. STORAGE: Water is placed in a closed tank or reservoir
for disinfection to take pace. The water then flows through pipes
to home and business in the community WATER FROM SEDIMENTATION
Slide 28
Water Disinfection Purpose of disinfection: To make Drinking
water free of any disease causing bacteria and microbes. Methods of
disinfection: There are 3 mainly used disinfection methods at large
scale. CHLORINATION OZONATION ULTRAVIOLET RADIATION
Slide 29
CHLORINATION Chlorine is the most common cost-effective means
of disinfecting water in the U.S. The addition of a small amount of
chlorine is highly effective against most bacteria, viruses, and
protozoa. OZONATION OZONE is Strongest oxidant/disinfectant
available. More effective against microbes than chlorination. But,
costly and difficult to monitor and control under different
condition.
Slide 30
COAGULATION SEDIMENTATION FILTRATION DISINFECTION STORAGE
COMPLETE CYCLE OF WATER TREATMENT:
Slide 31
What is wastewater treatment? Usually refer to sewage
treatment, or domestic wastewater treatment process of removing
contaminants from wastewater, both runoff and domestic Residences
(kitchen, bathroom) Commercial institutions Industrial institutions
(usually require specialized treatment process) Where does
wastewater come from? collected and transported via a network of
pipes and pump stations to a municipal treatment plant How can it
be treated?
Slide 32
3 stages of water treatment Primary solids are separated
Secondary dissolved biological matter is converted into a solid
mass by using water-borne bacteria 95% of the suspended molecules
should be removed Tertiary biological solids are neutralized then
disposed, and treated water may be disinfected chemically or
physically
Slide 33
Sedimentation Treatment Remove grease, oil Solids settle,
floating material rise to the surface Produce a homologous liquid
for later biological treatment Sludge is pumped to sludge treatment
plant Treatment stages Primary treatment
Slide 34
Filters bed Spread wastewater over microorganism made of
carbonised coal, limestone chips or specially fabricated plastic
media Degrade biological content (dissolved organic matter) of the
sewage Ex: human effluent, food waste, soaps, detergent Added
bacteria and protozoa into sewage Treatment stages - Secondary
treatment
Slide 35
Slide 36
Treatment stages Tertiary treatment remove disease-causing
organisms from wastewater Chlorination Most common Advantages: low
cost & effective Disadvantages: chlorine residue could be
harmful to environment UV light radiation Damage the genetic
structure of bacteria, viruses and other pathogens. Advantages: no
chemicals are used - water taste more natural Disadvantages: high
maintenance of the UV-lamp Ozonation Oxidized most pathogenic
microorganisms Advantages: safer than chlorination fewer
disinfection by-product Disadvantage: high cost
Slide 37
What can the effluent be used for? discharged into a stream,
river, bay, lagoon or wetland used for the irrigation of a golf
course, green way or park If its sufficiently clean, it can be used
for groundwater recharge Nitrogen removal Ammonia (NH 3 ) nitrite
(NO 2 - ) nitrate (NO 3 - ) Phosphorous removal Precipitation with
iron or aluminums salt Lead to eutrophication May cause algae bloom
Advanced Treatment
Slide 38
Summary
Slide 39
Onondaga Lake Many different types of contaminants can pollute
water and render it unusable. Pollutants regulated in the United
States under national primary drinking water standards include:
Microorganisms such as cryptosporidium, giardia, and fecal coliform
bacteria Disinfectants and water disinfection byproducts including
chlorine, bromate, and chlorite Inorganic chemicals such as
arsenic, cadmium, lead, and mercury Organic chemicals such as
benzene, dioxin, and vinyl chloride Radionuclides including uranium
and radium