October 20, 2011

Urban Science Adventure: Make a model landfill (and support science classrooms, too)

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American

What happens after you discard something into the trash can? Does it disappear? Does it simply go away? What happens to it? Well, those questions are the types of real inquiry, practical science that inner-city teachers like Mrs. Teece of Northwest Academy in St. Louis, Missouri, explores with her high school science students.

In our school we strive to create an environment that emphasizes the importance of college. We remind them every day that they are, in fact, college bound. Despite the challenges they face, our students are motivated and they come to us with their ideas and opinions. They always express that "doing" helps them learn better than sitting. They want to create what their learning about. (emphasis mine)

This is so true. I selected her environmental science lesson "Our Trash Goes Where?" for my Donors Choose Campaign. Thanks to two amazing donors (@DocFreeRide and @EJWillingham) all they need is $162 more dollars to get the Lab activity kit they need to learn more about trash.

On supporting science journalism

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Plus, if you help me raise the necessary money before the Science Bloggers for Students challenge ends, Saturday, October 22, 2011, I'll personally lead a landfill lesson for Mrs. Teece's class. (Assuming she and the school administration are cool with this).

Your donation of $5, $10 or more could help cultivate the next generation of Urban Scientists. Help me make this lesson possible for these students. Please visit the Urban Science Blog Pageto donate.

In the meantime, it's a super cool activity you can do at home or after school.

What happens to trash when you throw it away?”

Trash does not simply go away. Trash is taken to municipal landfills or dumps. Each day landfills receive trash, spread it out, and cover it with a layer of soil. Sometimes, the soil is mixed with sludge from sewers. However, the soil and trash layers are routinely compacted so as to use the space most effectively. Within the layers of soil trash is being decomposed. Compacting decreases the rate of decomposition of trash. Decomposition is the chemical breakdown of materials and requires air (oxygen) and water to hasten the process. Leachate and methane are two by-products of decomposition. Both are potentially hazardous and as a result landfills are regulated so as to reduce the negative impacts of these by-products. Leachate can potentially contaminate municipal water sources such as groundwater and aquifers, therefore all landfills must be lined with either plastic or clay to prevent leachate pollution.

Click on the image below to learn more about how landfills work.

As trash breaks down a dangerous byproduct is produced - leacheate. Landfills not only must take care of trash, but it also must not pose other health and environmental threats, too.

Here is how a typical landfill is constructed.

So, a landfill must not let the liquid contaminants seep into the ground water or soil. Therefore, all landfills must be lined with either plastic or clay to prevent leachate pollution.

But which landfill liner is better? Which will successfully prevent leachate pollution? Clay or plastic?

Here's an activity you could do at home or with your youth group.

Supply List:

transparent 2-liter soda bottles cut in half with cap
1 bag each of sand, gravel, topsoil, clay dirt
plastic wrap
food coloring - red or blue or green
jug of water

Instructions:

tap 3 holes in the bottle cap.
replace the bottle cap on the bottle.
after cutting the bottle in half place the top half of the bottle, cap-side-down, inside of the bottom half of the bottle.
place your liner at the bottom. If plastic - lay it on the bottom and press flat. If clay, pack it down with your fingers.
randomly select any or all three of the soils - sand, gravel, topsoil and begin layering the soils. be sure to pack them with your fingers. Or use the materials recommended on the cards.
you can layer your soils as thick as you want and as few or many layers as you want.
when you're down constructing your land fill, add a few drops of food coloring to your jusg of water. The colored water represents leacheate.
pour the colored water into your landfill and watch how fast the water drains.

What happened? Did the leachate leak through?

Repeat the exercise and change your materials or do it with friends. What did others find? How do different landfills compare? Was using clay or a plastic liner the most effective way of preventing leachate pollution?

Throw it Away. Where is Away? Landfills.

Make your own model Landfill

Filling up Landfills

Prolonging Landfill Life

Keep E-Waste Out of Landfills