Ocean Grade: Adaptable to all levels By: Jill Rivero MA: Science Education For the Wyland Foundation

Transcription

1 Water Treatment From Drain to Drink Grade: Adaptable to all levels By: Jill Rivero MA: Science Education For the Wyland Foundation OBJECTIVE: Students will understand what it means to conserve water, where our water comes from, and how it is cleaned and treated from drain to drink. PURPOSE: To educate students on where our water comes from, and the different ways a community can conserve and treat their water supply after it disappears down the drain, only to re-emerge as clean drinking water from the tap. VOCABULARY: Conservation, Desalination, Recycling, Drought, Waste Water Treatment Plant, Aquifer, Filtration, Sludge, Flocs, Coagulate, Sewage, Alum, Chlorine, Irrigation, Snowpack, Tap water, Effluent, Potable, Ultra violet lighting, Primary treatment, Secondary treatment, Tertiary treatment, settling basin, clarifier Discussion Questions: What does it mean to conserve water? (Recycling, Irrigation, Conservation ) What is a drought? (Lack of water, Drought) Where does our water come from? (Mountain Snow packs, Aquifers, Desalination ) Where does our water go after going down the drain? (Waste Water Treatment Plant, Filtration, Sludge, Flocs, Coagulation, Sewage, Alum, Chlorine, Tap water, Effluent, Potable, Ultra Violet lighting, Primary treatment, Secondary treatment, Tertiary treatment, Settling basin, Clarifier) 1 Water Treatment From Drain to Drink

2 Introduction: Conserving water incudes many methods; recycling, reducing usage of, and reusing water in various ways. (Purple pipes). Normally, the Water Cycle is balanced in nature, dumping as much precipitation on land and oceans as is evaporated. However, in certain parts of the world, an imbalance occurs, causing long term droughts or smaller snowpack s like in the Sierra Nevada Mountains, in California. California and many other places have experienced major droughts in the past, or lack of rain fall/snow fall. This year was the worst drought in California history and the Sierra Nevada snow pack was the lowest recorded snow accumulation in California history. When this snow melts, Californians use this water for irrigation as well as drinking water once it has been treated. Many people also rely on underground water reservoirs known as aquifers. These immense ground water storage areas provide many areas of the world with clean fresh water for irrigation, and drinking water for livestock and people. When these aquifers are over used and abused, they become depleted and a lack of water can result, forcing people to rely on outside methods for water, such as Desalination. Desalination is a method where people can treat saltwater from oceans and seas to make fresh water by removing the salt from the water. It can be an expensive procedure however, due to the energy and materials needed to treat the saltwater. Catalina Island, off the coast of Long Beach, California, uses a Desalination plant to treat drinking water for its major city, Avalon. But what happens to water after it is used by humans as it goes down the Drain? and how does it reemerge as tap water from our faucets and become drinking water? Background Information: Outside of using wells, which draw upon untreated underground bodies of water, most towns and cities use treated water to drink, irrigate and water their gardens and crops, and to wash their clothes with. This water comes from faucets, or taps, and is called tap water. But how did it get to our faucets, and how did it become clean again enough to drink? Most city water and waters used from small towns definitely needs some form of treatment before it can be consumed and used again in homes and in agriculture. Most water is cleaned at a Waste Water Treatment Plant or facility where it goes through several steps in order to obtain satisfactory levels of cleanliness. One of the first steps is filtration. This is called primary treatment, where the wastewater, also called sewage, arrives in pipes from homes and businesses and is then passed through a series of bar screens large enough to trap larger solid particles and lets the rest of the water pass through. Secondly, the water then flows into a holding tank called a settling basin or clarifier, where it will sit still for several hours to days in order to allow for any leftover chunks of sediment and particles, called sludge, to sink to the bottom. Next, secondary treatment begins where water is filtered through a bed of gravel containing microorganisms that help break down the smaller particles into even smaller sediments. The water arrives in a second holding tank, where chemicals, such as alum, are added in order to create flocs, to help the smaller particles stick, or coagulate, together in order to become larger globs that will sink. Tertiary treatment can then begin after this process where 2 Water Treatment From Drain to Drink

3 water is life the water flows out into a third tank to be further treated. Any excess water is then allowed to flow out into an outflow pipe into either the ocean or a nearby water source such as a stream or river and is called effluent. Tertiary treatment includes adding chlorine to kill the micro-organisms, and sometimes the water is passed through a final exposure to U-V lighting, or ultra-violet lighting which also kills any bacteria or diseasecausing organisms. Now the water is potable or officially tested and rendered safe to drink. 3 Water Treatment From Drain to Drink

4 TIME NEEDED: 1 hour CLASS PREP and BACKGROUND RESEARCH: 1. Please view the following You Tube videos as a class: For Elementary: For Middle School: (3 min) FOR HIGH SCHOOL: and 2. As a class, discuss their reaction to the videos and allow time for questions and comments. 3. Complete the lab below as a class in groups of 3 or 4. Answer the questions that follow in complete sentences. 4 Water Treatment From Drain to Drink

5 NAME: Date: Period: LAB: MATERIALS: mesh screening, 3 beakers ( mL) or 3 large graduated cylinders (1000 ml) per group, 300 ml of water for each group, collected from a stream or nearby freshwater source, or water polluted with coffee grounds or soil to imitate dirty water, gravel, aquarium carbon filtration packs, organic soil potting mix, toilet paper cut into 1 X 5 cm pieces, alum powder, sand, soup cans with both ends removed, one for each group. HYPOTHESIS: If we treat polluted water through three different methods, then we predict that the cleanest water will emerge after the (primary, secondary, tertiary) treatment. PROCEDURE: 1. Divide students into groups of 3 or Have students fill a ml beaker or 1000mL graduated cylinder ¾ full with polluted water. (This water can be made to look polluted using coffee grounds or soil if a local source of water cannot be found). 3. Have students drop 5-10 grams of organic potting soil into their polluted water samples. Have students record the color of the water on the data table below according to the number it most closely resembles on the color chart below. 4. Have students add 5-6 pieces of 1 X 5 cm pieces of toilet paper to their polluted water samples. 5. Next, have students create a small 5 X 5 cm screen using mesh screening in order to filter the polluted water for larger solid particles. 6. As a group, strain the group s polluted water sample through the 5 X 5 cm screen to collect larger solid soil particles and set aside any solid particles obtained. This simulates the Primary water treatment process. Have students record the color of the water on the data table below according to the number it most closely resembles on the color chart below. 7. Next, have students clean their mesh screen of any large particles and lay their mesh screen horizontally across a second 500 ml beaker and place the soup can with both ends removed on top. Fill the soup can with a 5 cm layer of gravel, a 5 cm layer of aquarium carbon filtration (removed from its pack) and finally a 5 cm layer of sand on top. This will simulate the Secondary water treatment process. 5 Water Treatment From Drain to Drink

6 8. Have students slowly pour their sample of polluted water through these two layers and record the color of the water that filters through on the data table below according to the number it most closely resembles on the color chart below. 9. Finally, have students mix 5 grams of alum powder with their filtered polluted water samples in a third beaker or graduated cylinder and record the color of the water on the data table below according to the number it most closely resembles on the color chart below. 10. Have students repeat the above process a second and third time in order to collect three sets of data to compare to one another. Make sure to use the same water source or the same amounts of coffee grounds or soil added as the first trial to ensure a controlled experiment has been conducted. 11. Allow time for students to answer the questions that follow and to write a Summary Conclusion. DATA TABLE 1: 6 Water Treatment From Drain to Drink

7 COLOR CHART: INTERPRETING DATA: WATER TREATMENT PROCESS: 1) What color number did your polluted water start off as? What color number did your water sample match after Primary treatment? Was it the same as when you started? Why or why not? 2) What color number did your polluted water sample match after Secondary treatment? Was it the same as your primary treated water? Why or why not? 3) What color number did your polluted sample match after the Tertiary water treatment? Was it the same as your secondary treated water? Why or why not? ANALYSIS: 4) Which of the above water treatment methods worked the best in changing the color of the water? Why do you think this is? 5) If your city did not treat its polluted water, what do you think would happen to people s health? 6) If you were sent to help people in a country that did not have clean water, what would you do first to help them have clean water? Which of the above processes would be the most important? 7) What is the difference between recycled water and potable water? (You may have to research this online In California, purple pipes are used to irrigate using recycled water.) 8) What happens to the remaining solid waste after it is collected from polluted water? (You may have to research this online as well). Could it be used for something else other than landfill material? 7 Water Treatment From Drain to Drink

8 SUMMARY CONCLUSION: Please write a 3-5 sentence paragraph using at least 5 of the words from the word bank below. Try to describe what happened during this lab according to your data and what you learned from your data. WORD BANK: Conservation, Desalination, Recycling, Drought, Waste Water Treatment Plant, Aquifer, Filtration, Sludge, Flocs, Coagulate, Sewage, Alum, Chlorine, Irrigation, Snowpack, Tap water, Effluent, Potable, Ultra violet lighting, Primary treatment, Secondary treatment, Tertiary treatment, settling basin, clarifier 8 Water Treatment From Drain to Drink