Chapter 1.D.

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Chapter 1.D.

• Water Cycle

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1.D. Water Treatment and PurificationDo Now

• Read pgs 86 - 89. Answer the questions
• 1. Why do we treat our water?
• 2. How does the natural hydrological cycle help
  purify water?
• 3. Why is chlorine added to the water?
• 4. What is flocculation?
• 5. List one addition purification step.

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Objectives

• SWBAT describe the natural hydrologic water cycle
  and the municipal water treatment cycle.
• SWBAT compare and contrast between both cycles.

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Natures Hydrological Cycle
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Natures Hydrological Cycle

• Steps that aid in purification
• 1. Distillation
• -evaporation of water leaving behind dissolved
  ions.
• 2. Aeration
• -water that trickles over rocks allows volatile
  impurities, previously dissolved, to be released
  into the air.
• -growth of microscopic plant and animal
  organisms that use certain water contaminants for
  food and energy.3. Sedimentation
• -separation of solids particles from slow
  moving streams
• 4. Filtration
• -Silt and clay particles removal as water
  filtrates sandy soil.

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Did You Know

• Residence time How long water stays in one
  place
• In glaciers and ice caps-replaced every 20-100
  yrs
• In the atmosphere-replaced every 8 days
• Reserviors-1 to 2 months

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Do Now

• Get with a partner and draw the hydrological
  cycle with labels!
• Leave your homework on your desk WITH your name
  on it!

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Objectives

• SWBAT describe the natural hydrologic water cycle
  and the municipal water treatment cycle.
• SWBAT compare and contrast between both cycles.

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Municipal Pre-Use Water Treatment

• Scan in image

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Municipal Water Treatment

• Steps to Water Treatment
• 1. Screening

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Steps to Treatment (cont.)

• 2. Prechlorination
• 3.Flocculation

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Steps to Treatment (cont.)

• 4. Settling
• 5. Sand Filtration

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Steps to Treatment (cont.)

• 6. Postchlorination

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Optional Further Treatment

• Aeration
• pH Adjustment
• Fluoridation

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Use pages 85-89 to fill in the following chart
Natures Cycle Municipal Treatment
Evaporation
Bacterial Action
Filtration
Other
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Do Now

• List the steps of municipal water treatment.

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Objectives

• 1. SWBAT explain why chlorine is added to the
  water supply.
• 2. SWBAT explain the relationship between
  chlorine and cancer.
• 3. SWBAT compare and contrast bottle vs. tap
  water perks and problems associated with it.

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Chlorine in Water supplies

• Chlorine is added to the water supply in 3 ways
• Chlorine Gas
• Sodium hypochlorite (NaOCl)
• Calcium hypochlorite Ca(OCl)2
• Most active form of chlorine in water is
• HOCl (hypochlorous acid)

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Chlorine can form Carcinogens.

• Chlorine can react with organic compounds to form
  trihalomethanes (THMs) such as chloroform.
  (CHCl3)
• Limits the amount of chlorine added to water

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Chlorination and THMs
Charcoal Filter Ozone or UV Light Eliminate Prechlorination
Advantages -Remove THMs -Remove THMs Less chlorine
Disadvantages -Expensive -Difficult to dispose of -Does not protect water once it has left the plant Less chlorine could mean more bacterial growth in water
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Are these pure, clean and better than ordinary
tap water?
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Bottled Water vs. Tap Water

• What are some factors that you should consider in
  deciding whether to drink bottle or tap water?

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Hard Water

• Water containing excessive dissolved
• Calcium (Ca2)
• Magnesium (Mg2)
• Iron (III) Fe3

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D.8. Water and Water Softening

• Affects the cleaning action of soap
• Soap can react with hard water ions to form
  insoluble compounds
• Soap Scum
• Soap Curds on clothing, skin and hair

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Hydrogen carbonate ions in Hard water

• HCO3- can cause calcium carbonate to form in
  water
• This can build in pipes, hot water heaters, etc.
• Takes longer to heat water (Blocks heat flow)

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Water Softening

• Remove hard water ions
• Adding sodium carbonate (Na2CO3) Washing Soda
• Precipitates will be washed away with water

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Common Water Softening Substances

• Borax
• Trisodium phosphate
• Calgon (hexametaphosphate)

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Detergents

• Work like soaps but dont leave behind hard water
  ions
• Early ones were not biodegradable

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Think-Pair-Share

• Explain what you see
• Use the words polar and non polar
• Hint look at whats not dissolving
• Pg. 97 Figure 1.59

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Do Now

• How do detergents differ from other soaps?

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Built in Water Softeners

• Contains ion exchange resin
• Filled with Na ions
• Hard water ions are attracted to it
• Clean resin with NaCl
• Usually done at night (hours long process)

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Figure 1.60
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Homework

• Read pgs. 90-94
• Pg. 102 1-11

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Do Now

• 1. Chlorine is often used to kill bacteria in
  town water supplies. List two alternate methods
  to help disinfect water.
• 2. What problems are associated with each?

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Objectives

• SWBAT define hard water and list problems
  associated with it.
• SWBAT review their answers to last nights
  homework.
• SWBAT work on their projects with their partners.
  

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Use pages 85-89 to fill in the following chart
Natures Cycle Municipal Treatment
Evaporation
Bacterial Action
Filtration
Other
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Do Now

• What is hard water?

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Do Now

• List 2 ways to soften water.

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Objectives

• 1. SWBAT identify the different ions found in
  hard water and the problems associated with it.
• 2. SWBAT answer questions on section 1.D.

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Objectives

• 1. SWBAT explain how an ion exchange resin works.
• 2. SWBAT draw pictures of the ion exchange resin
  on the molecular level.

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Do Now

• What things need to be done for your project?
• Your Project is DUE Wed. January 13th

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Objectives

• 1. SWBAT work in groups to create a presentation
  and practice the presentation in front of their
  peers.
• 2. SWBAT create 2 questions to ask the other
  groups

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Materials for you to Use

• Stop Watches
• Laptops
• Notecards
• Paper/Pencils/Markers

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Objectives

• 1. SWBAT correct incorrect homework answers and
  explain why.
• 2. SWBAT answer multiple choice and short answer
  review questions

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Test on FRIDAY Any questions?

• Review Sheet