Chapter 1.D. Water Cycle

1.D. Water Treatment and Purification Do 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.

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

Nature’s Hydrological Cycle

Nature’s 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.

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

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

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

Municipal Pre-Use Water Treatment Scan in image

Municipal Water Treatment Steps to Water Treatment 1. Screening

Steps to Treatment (cont.) 2. Prechlorination 3.Flocculation:

Steps to Treatment (cont.) 4. Settling: 5. Sand Filtration:

Steps to Treatment (cont.) 6. Postchlorination

Optional Further Treatment Aeration: pH Adjustment Fluoridation:

Use pages 85-89 to fill in the following chart Nature’s Cycle Municipal Treatment Evaporation Bacterial Action Filtration Other

Do Now List the steps of municipal water treatment.

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.

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)

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

Chlorination and THMs Charcoal Filter Ozone or UV Light Eliminate Prechlorination Advantages -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

Are these pure, clean and better than ordinary tap water?

Bottled Water vs. Tap Water What are some factors that you should consider in deciding whether to drink bottle or tap water?

Hard Water Water containing excessive dissolved: Calcium (Ca2+) Magnesium (Mg2+) Iron (III) Fe3+

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

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)

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

Common Water Softening Substances Borax Trisodium phosphate Calgon (hexametaphosphate)

Detergents Work like soaps but don’t leave behind hard water ions Early ones were not biodegradable

Think-Pair-Share Explain what you see Use the words polar and non polar Hint look at what’s not dissolving Pg. 97 Figure 1.59

Do Now How do detergents differ from other soaps?

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)

Figure 1.60

Homework Read pgs. 90-94 Pg. 102 # 1-11

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?

Objectives SWBAT define hard water and list problems associated with it. SWBAT review their answers to last night’s homework. SWBAT work on their projects with their partners.

Use pages 85-89 to fill in the following chart Nature’s Cycle Municipal Treatment Evaporation Bacterial Action Filtration Other

Do Now What is hard water?

Do Now List 2 ways to soften water.

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.

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

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

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

Materials for you to Use Stop Watches Laptops Notecards Paper/Pencils/Markers

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

Test on FRIDAY… Any questions? Review Sheet