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Opening Assignment What is the primary goal of water purification?

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2 Opening Assignment What is the primary goal of water purification?

3 Rotifers and Paramecium in some pond water viewed through a microscope Water found in ponds, lakes, rivers and streams usually has a wide variety of organisms living in it. Some of these living things are too small to see without the aid of a microscope. Untreated water may look clear and clean to us, but may still contain microorganisms (bacteria, protozoa, algae, rotifers, worms, insect larva and others) that are invisible to our naked eye. Because some of these organisms can cause illness if ingested, it is important to remove or kill them from water before drinking it.

4 Listed here are just a few of the many water-borne diseases with the type of microorganism that causes it: Hepatitis (virus) Polio (virus) Cholera (bacteria) Typhoid (bacteria) Giardia (protozoan) Cryptosporidium (protozoan)

5 THE GLOBAL IMPACT OF CHOLERA Cholera is caused by the bacterium Vibrio cholera. People become infected after eating food or drinking water that has been contaminated by the feces of infected persons. Control of cholera is a major problem in several Asian countries as well as in Africa. In the year 2000, some 140,000 cases resulting in approximately 5000 deaths were officially notified to World Health Organization. Africa accounted for 87% of these cases. Cholera cases and deaths for 2000: ContinentCasesDeaths África118,9324,610 America(s)3,10140 Asia**11,246232 Europe350 Oceania3,75726

6 What are some of the ways water is treated? Boiling water kills some germs but does not remove all of them or chemicals and dirt. Chemical treatment (chlorine) kills bacteria and viruses. It is the most common method to disinfect water. Flocculation happens when a chemical is added that makes small particles collect together to form larger clumps that are heavier than water. Sedimentation happens when particles settle out of the water. Filtration moves water through layers of trapping material (such as sand) or passes water through a membrane that has pores to exclude contaminants such as microorganisms, dirt and chemicals. Water treatment plants remove or kill microorganisms before sending water through a closed network of piping and into our homes, schools and businesses. With the exception of boiling the water, they may use all of these methods mentioned above to make our water safe to drink.

7 Some filters keep things from passing completely through by trapping them. See how the red dots (the contaminants) are trapped inside the filter above.

8 Membrane filters are a barrier for contaminants in water that are too large to pass through, and some contaminants will have a problem getting through because of their odd shape. When you make macaroni, the macaroni is mixed in with water. To separate them, you pour both the pasta and the water into a sieve or colander. The water goes right through the holes, but the macaroni stays on top.

9 Your group has been given a mixture of “microcandyisms”, but you have discovered that not all the candy microorganisms are safe. You need to somehow produce a cup of PURE NERDS. Your group must design and build a filtration system that will: Separate out the big microorganisms (Gobstoppers and Smarties) first. Remove the bacterial-looking Mike and Ikes and Skittles from the mix next. Produce a batch of pure NERDS! You and your partner(s) must design a filter using the supplies on your tables or on the “free resources” table to filter the smallest

10 Use the paper plates as filter holders. Cut out the center of the plate. Design a set of filters using any of the available materials. Use your imagination to arrange holes in the plates, netting, string or paper strips to create the size and shape of holes for each filter that will get the job done. Filter your “water” onto another plate.

11 1. What two physical properties of the microcandyisms did you need to take into account in order to create your filter system? 2. What do you think would have changed if the objects got wet or stuck to other objects? 3. Google the term “activated carbon” and explain how it works to filter water.


13 Get a blank piece of paper out and title it “Water Filtration Experiment”. You will work with your group again to design a water filter. Our question: Does activated carbon help to purify water? Hypothesis: (If, then, because) If we use....

14 Variables: Dependent: Independent: Constants: Materials List: Make a complete list of all the materials you will use in your experiment. Procedure: You will come up with your own procedures using the materials available. Don’t forget to give specific details on how you build it and on the metric measurements you used.

15 Since these measurements will be primarily qualitative, create a simple chart to collect your data. Example: Test A w/o Activated Carbon Test B with Activated Carbon Water clarity at start Water clarity at 5 minutes Water clarity at 10 minutes

16 Get in your lab group from yesterday and write a “high school” level conclusion that explains the following. Was your hypothesis supported or not? Explain Were there any possible sources of error? How can this information be used to create further experiments? How can this information help society?

17 You will now complete the water use worksheet to estimate how much water you use (waste) each day and then compare your total to someone who lives in a more underdeveloped country.

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