Hands-on Activity Protect Your Body, Filter Your Water!

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Quick Look

Grade Level: 8 (7-8)

Time Required: 2 hours

(two 60- minute class periods)

Expendable Cost/Group: US $22.50

Many materials are reusable lab supplies and equipment; see the Materials List for details.

Group Size: 3

Activity Dependency: None

Subject Areas: Earth and Space, Science and Technology

NGSS Performance Expectations:

NGSS Three Dimensional Triangle
MS-ESS3-3
MS-ETS1-2
MS-ETS1-4

A diagram shows a human body silhouette with major internal organs drawn inside, surrounded by images of various forms of pollution: waste pipes indicating water pollution (bacteria, parasites, chemicals) and industry and farming contributing to soil contamination (pesticides). Arrows point to the body, indicating consequences such as headaches, fatigue, cardiovascular illness, gastroenteritis, cancer risk, nausea and skin irritation.
It's a modern-day engineering challenge to remove human-made contaminants from drinking water.
copyright
Copyright © 2009 Mikael Häggström, Wikimedia Commons https://commons.wikimedia.org/wiki/File:Health_effects_of_pollution.png

Summary

Students make sense of the problem with drinking water contamination due to various pharmaceuticals and hormones. They experience the steps of the engineering design process as they design solutions for a real-world problem that could affect their health. Substances such as prescription medication, pesticides and hormones are detected in the drinking water supplies of American and European metropolitan cities. Using chlorine as a proxy for estrogen and other drugs found in water, student groups design and test prototype devices that remove the contamination as efficiently and effectively as possible. They use plastic tubing and assorted materials such as activated carbon, cotton balls, felt and cloth to create filters with the capability to regulate water flow to optimize the cleaning effect. They use water quality test strips to assess their success and redesign for improvement. They conclude by writing comprehensive summary design reports while reflecting on how engineers can design solutions to help detect and effectively remove these contaminants from our drinking water.
This engineering curriculum aligns to Next Generation Science Standards (NGSS).

Engineering Connection

The water that comes from our faucets has passed through a complex system designed by many different types of engineers. Civil, chemical, electrical, environmental, geotechnical, hydraulic, structural and architectural engineers all play roles in the design, development and implementation of municipalities' drinking water supplies and delivery systems. Hydraulic engineers design systems that safely filter the water at a rate needed to supply a specific region and population. Chemical engineers precisely determine the amounts and types of chemicals added to source water for coagulation and decontamination to make the water safe to drink and not taste bad. Even so, modern pharmaceutical and agricultural practices persist in contaminating our water supplies. In this activity, students play the role of engineers challenged to design-build-test filtration devices to regulate flow and maximize output and decontamination.

Learning Objectives

After this activity, students should be able to:

  • Make sense of how pharmaceuticals and hormones have resulted in pervasive water contamination.
  • Describe the effects humans have on the quality of water on Earth.
  • Follow the steps of the engineering design process while designing and building prototype devices to filter contaminants from a liquid solution.
  • Design a system that regulates flow rate to maximize effectiveness of treatment.
  • Filter out 75% of the chlorine from a provided chlorine solution.
  • In a summary engineering design report, describe the materials used by explaining their use and effectiveness.
  • Complete Claim-Evidence-Reasoning statements for questions posed.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS Performance Expectation

MS-ESS3-3. Apply scientific principles to design a method for monitoring and minimizing a human impact on the environment. (Grades 6 - 8)

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This activity focuses on the following Three Dimensional Learning aspects of NGSS:
Science & Engineering Practices Disciplinary Core Ideas Crosscutting Concepts
Apply scientific principles to design an object, tool, process or system.

Alignment agreement:

Ask questions that can be investigated within the scope of the classroom, outdoor environment, and museums and other public facilities with available resources and, when appropriate, frame a hypothesis based on observations and scientific principles.

Alignment agreement:

Construct an oral and written argument supported by empirical evidence and scientific reasoning to support or refute an explanation or a model for a phenomenon or a solution to a problem.

Alignment agreement:

Human activities have significantly altered the biosphere, sometimes damaging or destroying natural habitats and causing the extinction of other species. But changes to Earth's environments can have different impacts (negative and positive) for different living things.

Alignment agreement:

The uses of technologies and any limitations on their use are driven by individual or societal needs, desires, and values; by the findings of scientific research; and by differences in such factors as climate, natural resources, and economic conditions. Thus technology use varies from region to region and over time.

Alignment agreement:

Cause and effect relationships may be used to predict phenomena in natural or designed systems.

Alignment agreement:

NGSS Performance Expectation

MS-ETS1-2. Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem. (Grades 6 - 8)

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Click to view other curriculum aligned to this Performance Expectation
This activity focuses on the following Three Dimensional Learning aspects of NGSS:
Science & Engineering Practices Disciplinary Core Ideas Crosscutting Concepts
Evaluate competing design solutions based on jointly developed and agreed-upon design criteria.

Alignment agreement:

There are systematic processes for evaluating solutions with respect to how well they meet the criteria and constraints of a problem.

Alignment agreement:

NGSS Performance Expectation

MS-ETS1-4. Develop a model to generate data for iterative testing and modification of a proposed object, tool, or process such that an optimal design can be achieved. (Grades 6 - 8)

Do you agree with this alignment?

Click to view other curriculum aligned to this Performance Expectation
This activity focuses on the following Three Dimensional Learning aspects of NGSS:
Science & Engineering Practices Disciplinary Core Ideas Crosscutting Concepts
Develop a model to generate data to test ideas about designed systems, including those representing inputs and outputs.

Alignment agreement:

Models of all kinds are important for testing solutions.

Alignment agreement:

The iterative process of testing the most promising solutions and modifying what is proposed on the basis of the test results leads to greater refinement and ultimately to an optimal solution.

Alignment agreement:

Models can be used to represent systems and their interactions.

Alignment agreement:

  • Students will develop an understanding of the attributes of design. (Grades K - 12) More Details

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  • Students will develop an understanding of engineering design. (Grades K - 12) More Details

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  • Students will develop abilities to apply the design process. (Grades K - 12) More Details

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  • Students will develop an understanding of the effects of technology on the environment. (Grades K - 12) More Details

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  • Humans devise technologies to reduce the negative consequences of other technologies. (Grades 9 - 12) More Details

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  • Describe and explain the purpose of a given prototype. (Grades 6 - 8) More Details

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  • Identify and explain the steps of the engineering design process, i.e., identify the need or problem, research the problem, develop possible solutions, select the best possible solution(s), construct a prototype, test and evaluate, communicate the solution(s), and redesign. (Grades 6 - 8) More Details

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  • Document and present solutions that include specifications, performance results, successes and remaining issues, and limitations. (Grades 9 - 10) More Details

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Suggest an alignment not listed above

Materials List

Each group needs:

  • 1.5 foot (.46 m) plastic tubing or PVC pipe with 1.5 inch (3.81 cm) or greater inner diameter; available at hardware stores (see Figure 1, which shows an example tube that is longer than 1.5 feet; it is recommend to cut tubes to 1.5 feet to avoid difficulties in removing filter materials)
  • 2 250-ml beakers
  • 50-100 ml chlorinated water; this 200 ppm solution is prepared by the teacher using Clorox® germicidal bleach; see instructions in the Procedure section
  • 50-ml graduated cylinder
  • plastic spoon, to load sands and activated carbon
  • sieve, to separate small materials
  • lab safety gloves, one pair per student per day, such as disposable nitrile gloves available at https://www.amazon.com/s/ref=nb_sb_noss_1?url=node%3D4954444011&field-keywords=disposable+nitrile+gloves&rh=n%3A4954444011%2Ck%3Adisposable+nitrile+gloves
  • lab book or notebook, one per student; alternatively, have students record all necessary information throughout the activity on blank sheets of paper and staple them together to serve as a lab "book" for the activity
  • safety goggles, enough so that each student in a team can wear goggles while handling and testing the chlorinated solution
  • Engineering Design Report Scoring Rubric, one per student
  • Claim-Evidence-Reasoning Graphic Organizer, one per student

To share with the entire class:

  • activated carbon, either granules or pellets; for cleanup, pellets are easier to separate with a sieve at activity end; see material life expectations note, below
  • filter media, such as cotton balls, fish filter media, carbon infused filter media, 50 micron felt pad, cheesecloth, cotton cloth or whatever is available
  • fine-grained sand
  • (for teacher use only!) Clorox® germicidal bleach; used to make a chlorinated water solution; 2 teaspoons bleach per gallon of water
  • pitcher or other container large enough to hold a gallon of water, for preparing the chlorinated water
  • "free" and total low-level chlorine water quality test strips, such as Hach's "Free & Total Chlorine Test Strips, 0-10 mg/l," 50 strips, 0-10 ppm, at https://www.hach.com/free-total-chlorine-test-strips-0-10-mg-l/product-details?id=7640211603
  • sanitizer-strength chlorine test strips, such as LaMotte's "4250-BJ sanitizer strength chlorine test strips," 200 strips, 0-200 ppm, from Cole-Parmer at https://www.coleparmer.com/i/mn/9953231
  • stopwatch
  • sink, tap water, soap, towels

Note: A pound of activated carbon can remove 200 ppm chlorine from 843 gallons, as calculated from http://www.waterprofessionals.com/learning-center/dechlorination/. Thus, a supply of activated carbon is reusable for several years of experiments.

Worksheets and Attachments

Visit [www.teachengineering.org/activities/view/wpi_protect_activity1] to print or download.

Pre-Req Knowledge

Students should have prior knowledge of the water cycle, groundwater movement and how current day municipal water treatment plants operate.

Introduction/Motivation

How many of you heard about not flushing any medications down the toilet or drain? (See raised hands) Perhaps you have seen your parent(s) cleaning the medicine cabinet and getting rid of unwanted or old medication by flushing them down the drain for easy disposal? 

Why do you think we shouldn’t do this? (Listen to student responses.)

Tell students to draw a T-Chart in their notebooks. Label the first column “What I Notice” and the second column “What I Wonder”. Have students write down what they notice (observations) and wonder (questions) about the following video: https://www.youtube.com/watch?v=XKCpeflOIUw.

Ask students to share their observations and questions they have about the video.

Now, show students the following infographic. Ask students to write down what they notice and wonder in their T-charts.

An infographic showing the process of how drugs end up in our drinking water.
Unprescribed: Drugs in the Water Cycle infographic
copyright
Copyright © Kelly Shea, Circle of Blue. https://www.circleofblue.org/2011/world/unprescribed-u-s-pharmaceutical-industry-fights-to-avoid-paying-for-drug-disposal-programs/

What do you notice? What remains in the drinking water? [Allow students to discuss and share responses]

During student discussion, guide students to notice that pharmaceutical chemicals still appear in drinking water even after it goes through water treatment and filtration.

(optional) Finally have students read through the following article: "Drugs in Our Drinking Water? Experts Put Potential Risks in Perspective After a Report that Drugs Are in the Water Supply." 

Ask students to construct an explanation for how pharmaceuticals appear in our drinking water- noting any causes and effects.

As the video, infographic and article suggest, our water waste-treatment facilities aren’t always designed to get rid of pharmaceutical compounds and hormones, allowing these contaminants to remain in our local waterways and even the water we drink.

Now that you are familiar with the problem, what question(s) do you have? (Listen to student responses, guiding students to ask how do scientists/engineers detect pharmaceuticals and other organic compounds in the water and what solutions might exist to help remove these compounds.) 

So, how do engineers detect these drugs in the water? And what solutions exist to help remove these contaminants from our drinking water and just how effective are they?

Today, acting as an environmental engineer, your challenge is to design a filtration device that could be implemented in a water treatment system to effectively remove estrogen and other organic compounds from drinking water as a final step in the filtration system.

Procedure

Background

Activated carbon (or charcoal) and sand filtration are commonly used to remove particles, organic matter, bacteria and pathogens from water. To keep aquariums healthy for fish, filters with activated carbon are employed to remove tap water chemicals and the chemicals produced from fish waste. Typically, municipal water treatment facilities do not use activated carbon in their filtration processes in order to reduce system cost and maintenance.

Provide students with research (see the References section) that documents the successful use of activated carbon to remove estrogen, the disinfectant that is added to water and other harmful pollutants that may be present in drinking water. Activated carbon reduces the amount of estrogen in drinking water by 60-80%.

Before the Activity

  • Gather materials and make copies of the Engineering Design Report Scoring Rubric (one per student) and the Claim-Evidence-Reasoning Graphic Organizer (one per student).
  • Depending on available supplies, set a maximum material amount that can be used by each group. For example, if you have 40 ounces of activated carbon available and 10 groups, set a 4 oz. maximum per team. If you only have one 24 x 24-inch square of felt, then each group may use a maximum of 2.4 x 2.4-inch square.
  • Prepare the chlorine solution: Pour 2 teaspoons of Clorox® germicidal bleach into 1 gallon of water to create a 200 ppm solution.

With the Students—Day 1

  1. Present the Introduction/Motivation content to the class.
  2. Review lab safety with students. Inform them that they will be using a bleach solution. Ask them to tell you what lab safety procedures apply to this situation. Refer to the guidelines suggested in the Safety Issues section. Remind students to wear lab gloves and safety goggles when handling and testing the chlorinated water.
  3. As a class, review the steps of the engineering design process. Refer to https://www.teachengineering.org/PDF/edp/TE_EDPTeacherMaterials_8.5x11.pdf The basic steps are: Identify the need and constraints, research the problem, develop possible solutions, build a prototype(s), test and evaluate the prototype(s), redesign as needed.
  4. Divide the class into groups of two or three students each. Or, if materials are scarce, organize the class into groups of three or four students each.
  5. Review the rubric with students so they understand the activity expectations and the assessment criteria.
  6. Explain to the class how activated carbon can attract and trap estrogen, organic compounds and chlorine. As water travels through students' prototype filter designs, it is important to be able to control the flow of the water in order to give the activated carbon time to remove the toxins. If the water goes through the activated carbon too fast, it will not purify the water because not enough contact time is provided; if water goes through the carbon too slowly, then the prototype is not efficient for practical use. In situations like this, engineers must find the balance that is most suitable for the purpose and goals of the device being designed.
  7. Inform students that they will be required to take apart their prototypes at the end of class and separate all materials. A sieve will be provided to separate any mixed sand and activated carbon. Other materials such as wool, filter media and felt will also be separated and returned to their designated storage spots.
  8. Do a few water quality tests in front of the class to demonstrate how to test water and read the results. First, use a 0-200 chlorine test strip to test the chlorinated solution that was made for the class. The solution should be 200 ppm chlorine. Then test the school's tap water, as taken from a drinking fountain or sink tap, using both the 0-200 chlorine test strip and the 0-10 chlorine test strip so you can compare the school's drinking water to the highly chlorinated water of the pre-made solution. Show students the test strips and how to compare their colors to the scale provided with each type.
  9. Give groups their filters (the tubes) and let them begin the design process. Inform them of the available supply of materials and any per group material limitations.
  10. Direct groups to start by brainstorming at least three different designs. Require (at least) one team member in each group to take notes and document all ideas from the brainstorming session, including sketching out various design ideas. Mention to students that throughout all the steps of the design process, engineers benefit from taking detailed notes of all their ideas and test results, including sketches.
    A photograph of a pen and ink drawing on aged parchment paper shows a triangular-shaped contraption with a seat, strap and long hinged arms. Parts are identified by letters and nearby cursive writing provides a description.
    Engineers take detailed notes of their ideas and test results, including sketches. This is a design for a flying machine by Leonardo da Vinci in 1488.
    copyright
    Copyright © 1488 Leonardo da Vinci, Wikimedia Commons https://commons.wikimedia.org/wiki/File:Design_for_a_Flying_Machine.jpg
  11. After groups have brainstormed multiple designs, direct them to discuss the merits of each design, comparing them to each other in order to select the most-promising design (or combine various ideas into one most-promising design). Next, have the teams create more detailed sketches of the chosen designs; make sure these drawings are labeled with dimensions/amounts and materials. Remind students to write down the reasoning behind the final design and each material selection, as well as how each is intended to function. Check each design sketch before permitting students to gather the necessary materials.
  12. Once teams have acquired their materials, direct them to begin creating their prototypes.
    A photograph shows a hand holding a curved section of about three to four feet of clear plastic tubing with different layers of carbon filter media—wool, felt and carbon pellets—entirely filling (blocking) the inside of the tubing near one end.
    Figure 1. One of the first prototypes! After this, tubes were cut shorter, to 1.5-foot lengths, after unloading proved to be difficult.
    copyright
    Copyright © 2014 Timothy S. Vaillancourt, Worcester Polytechnic Institute
  13. When 15 minutes are remaining in the period, direct students to test their current designs and come up with solutions to any problems they may want to fix during the next day.
  14. Testing procedure:
    • A group brings its prototype up to the teacher. They explain their design concept and the purpose of each layer in their filter prototype.
    • Then students hold the prototype vertically above a 250-ml beaker while the teacher pours 50 ml of 200 ppm chlorinated water into the prototype.
    • One student uses a stopwatch to record the time it takes for the water to move through the filter.
    • Once the liquid has stopped dripping out of the bottom of the prototype (to a rate of about one drip every five seconds), the teacher uses a chlorine test strip to test the dripping water to determine if students have achieved the goal of lower than 50 ppm chlorine. If they have, then the teacher uses a 0-10 ppm chlorine test strip to determine the best estimate of the chlorine concentration of the water.
    • Students also measure the amount of water retrieved from the filter.
    • In their lab notebooks, students record the chlorine concentration, the time it took the water to move through the filter, and the amount of water retrieved from their filters.
    • Direct the team to spend some time making notes about the "lessons learned" from the prototype testing. What worked? What did not work? What could be improved? What new ideas do you have? Analyze and interpret data to determine similarities and differences in findings. This prepares them for how to begin the next day.
  1. With five minutes left of the class period, have students disassemble their prototypes and separate all materials into piles of like materials so they are ready to be used for the next class.

With the Students—Day 2

  1. Direct students to redesign their filter prototypes with the same expectations of the previous day. This means that groups can modify or completely re-design their water filtration systems from the previous day.
  2. When teams have completed their revised prototype designs, they take them to the teacher and explain the purpose of each layer of the filter prototypes.
  3. With the teacher's help, groups test their (hopefully) improved prototypes. They measure the time it takes for water to pass through the system, the after-filtered chlorine concentration with the chlorine test strips, and the amount of water that was retrieved, as they did the previous day. Students record all results in their lab notebooks.
  4. Groups disassemble their filtration systems and separate the materials into piles for the next class or for storage.
  5. Direct students to answer the Guiding Questions in their lab books/journals, as provided in the Assessment section. Collect their lab books for grading.
  6. Direct students to begin individually writing up their observations and results into final engineering design reports, as described in the Assessment section. Give them a deadline to turn them in and grade them with guidance from the rubric.
  7. Reflecting on the questions from the activity Introduction, have students complete the Claim-Evidence-Reasoning Graphic Organizer, as described in the Assessment section.

Vocabulary/Definitions

aeration: Mixing air with a substance.

anthropogenic: Caused or produced by humans.

coagulation: The clumping of a material into larger particles. Example: Blood coagulates to stop a cut from bleeding.

estrogen: A hormone that is naturally found in the human body. This hormone maintains female characteristics of the body and is replicated in birth-control pills.

pharmaceutical: A drug that is used for medical reasons; may be available over-the-counter or prescribed by a doctor.

prototype: A first attempt or early model of a new product or creation. May be revised many times

sedimentation: The process of settling. Example: Particles settle to the bottom of a water column.

Assessment

 

Activity Embedded Assessment

Lab Book/Journal: Individually assess students based on the design and redesign documentation in their lab books or journals. Require each student's lab book to contain design ideas, prototype sketches and a description of the functionality and results from prototype testing. Expect students to include observations and hypotheses about their prototype designs and material use. Direct them to document their reasoning for each design they built and tested. For full credit, require students to answer the following Guiding Questions for the design portion of the lab book:

  • What are you trying to accomplish in the design of your water filtration device?
  • What are different ways to use the materials provided in your filtration device?
  • How can you control water flow to enable the chlorinated water to react with the activated carbon?
  • What is the purpose of each portion of the water filtration device your group decided to build?
  • What are the results of your water filtration device's test?
  • In what step of the water filtration process would you implement your design?

Post-Activity Assessment

Summary Engineering Design Reports: Students prepare and hand in engineering reports on their design work completed on both days, including the pros and cons of their designs. Grade students on their ability to critique their designs and their improvements from Day 1 to Day 2 and suggestions to further improve the prototypes. Students whose designs did not improve can still obtain high-achieving grades by thoroughly explaining the ways that their second designs did not work compared to their first designs and how they can further improve their designs. Use the Engineering Design Report Scoring Rubric for guidance in assessing students' reports.

Claim-Evidence-Reasoning: Revisit the questions from the Introduction of the activity: 

  • How do engineers detect pharmaceuticals in the water? 
  • What solutions exist to help remove these compounds from our drinking water and how effective are they?

Have students complete the Claim-Evidence-Reasoning Graphic Organizer. Students can refer to the second page for help with writing their reasoning. A rubric is also provided on the third page to help with grading their statements. Once complete, ask students to share their responses with the class. 

Safety Issues

Good lab practices for this activity:

  • Wear safety goggles and gloves when handling and testing the chlorine solution and filter materials (because they are re-used and thus contain the chlorine solution).
  • Bleach products at this level of concentration may cause skin irritation. If any chlorine solution gets in your eyes or mouths, immediately flush the area with water for 10 minutes.
  • If any solution gets on your skin, wash the skin with water and soap for five minutes.
  • If any solution spills on a desk or the floor notify the teacher so the spill can be cleaned up.

Activity Extensions

If time permits, conduct a materials analysis of scaling the best design in the class to a full-scale water treatment system that can filter 4.5 million gallons per day, which is the city of Marlborough, MA's average daily water use.

References

Doheny, Kathleen. "Drugs in Our Drinking Water? Experts Put Potential Risks in Perspective After a Report that Drugs Are in the Water Supply." Published March 10, 2008. WebMD Feature, WebMD. Accessed July 2, 2014. http://www.webmd.com/a-to-z-guides/features/drugs-in-our-drinking-water

Rowsell, Victoria F., Dawn S.C. Pang, Foteini Tsafou and Nikolaos Voulvoulis. "Removal of steroid estrogens from wastewater using granular activated carbon: comparison between virgin and reactivated carbon." Water Environment Research. April 2009, 81(4): 394-400. Print.

GRDULSKA, AGNIESZKA; KOWALIK, ROBERT. (2020, September). (PDF) estrogen removal from wastewater. Retrieved September 21, 2021, from https://www.researchgate.net/publication/348645180_ESTROGEN_REMOVAL_FROM_WASTEWATER.

Copyright

© 2015 by Regents of the University of Colorado; original © 2014 Worcester Polytechnic Institute

Contributors

Timothy S. Vaillancourt, Terri Camesano, Kristen Billiar, Jeanne Hubelbank

Supporting Program

Inquiry-Based Bioengineering Research and Design Experiences for Middle-School Teachers RET Program, Department of Biomedical Engineering, Worcester Polytechnic Institute

Acknowledgements

This activity was developed under National Science Foundation RET grant no. EEC 1132628. However, these contents do not necessarily represent the policies of the National Science Foundation, and you should not assume endorsement by the federal government.

Last modified: October 16, 2021

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