Engineering Unit: Design ProcessLesson: Water Filtration System Name of curriculum specialist Contact information of specialist
Activity Objectives Students will: Design and build a water filtration device Test the devise, make observations, and collect data. Collaborate as they analyze results and attempt to identify the best filter media to use. Based on their analysis and on study of other filtration devices they will make modifications to their model and repeat the process in an effort to produce the most effective filtration apparatus possible. Compare individual results and communicate their results to the larger community.
Prerequisites • Testing using litmus paper • Terms: pH, base, neutral, acid,
Preparation: Supply Lists To Make the Filtration Devices • safety glasses • 2-liter bottles (two per team) • cheesecloth • rubber bands • Masking tape • Utility knife or heavy duty scissors • Window Screen (if done by students) • Plastic wrap (if done by students) To Make Gray Water • tap water or bottled water • Italian Dressing Additional Preparation Supplies • mesh bag (panty hose) - to rinse charcoal, before beginning activity • clean water
Activity Supply Lists Filter Materials • aquarium gravel • play sand • activated carbon / activated charcoal marbles • cotton balls • coffee filters Additional Supplies • pH testing strips (litmus paper) • pH color chart (on student sheets) • metric rulers (one per team) • plastic cups • paper plates • metric liquid measuring cups
Making the Filtration Device Decide – will you do this ahead, or will the students do it? • Cut off the bottoms of the two liter bottles • Discard the caps • Cover the cut edges with masking tape Next…..
Making the Filtration Device If you are preparing ahead of time, • Cover the mouth of the bottle with at least 10 layers of cheesecloth and secure with rubber band. If students are preparing the device, • Ask them to choose a filter media for the mouths of each of their two devices. • The media does not have to be the same for both. • Choose from cheesecloth, metal screen, or plastic wrap.
Make “gray water” • pH test your tap water before making the solution. Start with “clean water” - pH between 6.5 and 7.5. • If your tap water is not between pH 6.5 and 7.5, then use store-bought drinking water. • Mix 1 part Italian salad dressing (vinegar and oil with seasonings, shaken) to 5 parts water. • Make enough for each group to have about 500 ml. • Note: pH of the gray water should be around 4. If needed, you can add vinegar to drop the pH.
Prep the Filter • Measure items to about 1 cup each • Each team will need up to 4 different items Rinse the Charcoal • Panty hose work well • Should be done before you are ready to begin the activity.
Beginning the Lesson • Put students in teams • Draw for filter materials • Put all material names on slips of paper and have each team draw 3 • If possible, allow students to also draw a 4th, free choice material • Distribute gray water, clean water and filter materials. • Distribute student handouts
Procedure • Put on safety glasses. • Place the bottle upside down with its mouth over the clear plastic cup to catch the filtered water • Make sure cup is large enough • Fill the bottle with the first filtering material to a depth of 5–8 centimeters (cm). • Team decides on the order in which to layer the materials • Coffee filters and cotton balls will need to be packed down. • Place the second filtering material to a depth of 5–8 cm on top of the first one. • Place the third filtering material to a depth of 5–8 cm on top of the second filtering material.
Procedure • Students should measure pH of clean water sample, and record. • Test run clean water through your water filtering system to make sure it will allow water to flow through. (10 to 16 oz.) • While the clean water runs, draw and label diagrams to match the filtration system.
Procedure • Empty and replace catch cup • With 350 ml of gray water • Observe and record characteristics • Measure pH and record • Run the water through the system • Observe and record characteristics • Measure pH and record • Discuss findings
Procedure • Change to clean catch cup • Run sample through a second time • Observe and record characteristics • Measure pH and record • Discuss findings
Sources and Career Links Thanks to subject matter experts Jitendra Joshi, Michele Perchonok, Debbie Berdich, Frederick Smith and Julia Hains-Allen for their contributions to KSNN™ and Noticiencias NASA™ on the development of this education material. Jitendra Joshi is the Lead Technologist for the Human Systems Research and Technology Program. You can find out more about what Mr. Joshi does at http://www.dsls.usra.edu/joshi.html. More information about Michele Perchonok, a food scientist at NASA’s Johnson Space Center, can be found at http://www.ift.org/cms/?pid=1000543. Debbie Berdich is the biomedical systems support for the JSC Habitation Systems Project. More information about her work can be found at http://esrt.jsc.nasa.gov/taehdt/project_overview/project_overview_main.htm and http://www.nasa.gov/vision/earth/everydaylife/real_glass.html. Frederick Smith is the Advanced Air Monitoring lead from Engineering Crew and Thermal Systems Division. More information about Mr. Smith can be found at http://quest.arc.nasa.gov/people/bios/space/smithf.html and http://advlifesupport.jsc.nasa.gov. Julia Hains-Allen is the Education Manager at NASA’s Specialized Center of Research and Training (NSCORT) focusing on "advanced life support". You can find out more about the projects and research being conducted in the area of advanced life support at http://www.alsnscort.org.