Provide Access to Clean Water
Water Filtration / 9th grade Biochemistry/Chemistry/Science
Fellow: Mike Edley
Teacher: Stephanie Dunda Class: 9th grade Biochemistry at SLA
NAE Grand Challenge: Provide Access to Clean Water
Objective: To study the NAE Grand Challenge “Provide Access to Clean Water”. During this 5-class period session, students will learn about water filtration and build a filter for a country/location that does not have access to clean water.
Summary: This was a 5 class period project where the students learned about water filtration through a combination of lecturing/independent research/experimentation. The end goal of the project was for the students to design their own water filtration system following a budget. We began by teaching the students about various water filtration processes such as reverse osmosis, and sand filtration, then taught them to build a mini water filtration system (filter 1 dixie cup of water) to use in the classroom. Dirty water was filtered and the students measured turbidity and microorganisms via a light microscope to quantify “cleanliness” of their water.
Materials: Cotton balls, Dixie cups, Styrofoam cups, dirty water (river water is best), Gravel, Activated Charcoal, Ethanol, Iodine, Turbidity meter, Microscopes, Agar, Petridish
See Day 1 Slideshow
Present the problem of dirty water. Because clean water is readily available in the United States many students are not aware that other regions of the world lack clean water. Many are surprised to find that more people die annually from lack of clean water than from war worldwide. Also many students don’t know about what engineers do to “clean” water. Present novel engineering advancenments in water purification, “life straw.” I also talked about a more traditional water purification technique, reverse osmosis. Many students have heard of this but do not know anything about the process.
Experiment: Have the students work in groups of 4 to build a water filter. See Day 1 Handout. On the first day it was important to give them strict instructions because they do not know the pros/cons of each filtration material that we had provided. Have the students quantify how clean the water is by measuring the turbidity
See Day 2 Slideshow
On the second day the students were moved to new groups. Because of this, we had the students discuss/brainstorm in the beginning of the class, what worked?, what didn’t work?, how do they think they should build their new filter?. Emphasize that engineers need to communicate to work effectively; no one can do everything by themselves. To encourage collaboration have each person in the group present an idea to the entire group, we tried to emphasize that you should listen to all ideas but that doesn’t necessarily mean you will have to agree with them. Discuss engineering design cycle. We wanted the students to try their own ideas for making the water filters but in general found resistance to trying new things because students are scared their idea won’t work. I tried to bring an example from my research to the class and show them that scientists/engineers have to be willing to fail a lot in order to get something to work and that even if you don’t ever solve the problem you might learn something interesting along the way.
Allow the students time to redesign their water filtration. They now have experience with the materials and should be able to formulate a new idea with their groups for making their water filter more effective.
Allow the students to build their water filters. Use turbidity to quantify how “clean” the water is and have students compare results between their old/new filter designs. We didn’t explain to the students how to use activated charcoal and many found it made their water “dirty.” Discuss at the end of class why and how they can fix it.
See Day 3 slideshow.
On day 3 we did not spend much time lecturing. I discussed the idea of a flow rate and how it is important that a water filtration not only filter water effectively but do it in a reasonable time. Introduce the idea of a budget for materials. Because of the introduction of flow rate/budget allow for extra planning time before entering the lab. Require groups to have a diagram of their water filtration idea in their lab books before they can enter the lab.
Allow the students to build their water filters and weigh out materials based on the budget. We created a competition, whichever group’s filter provided the highest transmittance and lowest cost was the winner. In the middle of the experiment we had a pause and reflect to further encourage teamwork.
For homework have the students research parts of the world where clean water is a major issue. Also have them research what materials are scarce/common in these areas (goes along with idea of a budget).
See Day 4 slideshow.
What areas of the world need clean water?
What materials are common that can also be used for water filtration? Which materials have we used which would not make sense for these countries to use?
We received many answers ranging from sand to nanodiamond powder.
Have the students make a water filter and instructional “how to” video for students their own age in a different country.
Day 4 Handout
See Day 5 Budget
What is “clean?” Discuss how turbidity only accounts for particulates in the water and that even water with 100% transmission may still be unsafe to drink. (Microrganisms) Discuss using techniques to disinfect water during/after filtration. (Boiling/Iodine/Ethanol).
Have students complete their final water filter design that includes a treatment plan for microorganisms. Also prepare petri dishes that they can culture the untreated and treated water to see the difference. Their final design was presented to a Navy Engineer who helped to critique and improve the design. At the end of this design they will create a final video that shows the steps to making their water filter, explains what each component is for, and includes tips/tricks for students their age to create a water filter.
The next class period can be used to look at cultured samples with microscopes (may take a day to incubate) and discuss/wrap up what the students learned about water filtration and the worldwide problem of providing clean water.