Recycling Rules: Understanding Recycling and a MRF

Mar 21 2011

Source: Keep America Beautiful

Summary Information

Keywords:

Materials Recovery Facility (MRF), waste stream, separation, sorting, recycling

Topic:

Earth Science

Physical Science

Workplace Skills:

Raising Questions

Problem Solving

Investigation Design

Planning investigation

Discussion

Recording & Reporting

Teamwork

Independent Thinking

Estimated Time Required:

1-2 hours

Target Grade (Ages):

Grade 6 (Ages 11-12)

Diversity Indicators:

This lesson is appropriate for all learners.

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LESSON

Goals and Prerequisites

Goals:

To familiarize students with how and why recyclable materials are separated at a materials recovery facility
To encourage students to use problem-solving skills

Prerequisites:

Students should:

Be familiar with sorting recyclable materials at their home or school
Be able to develop a hypothesis and apply the scientific method and design engineering principles

Instructional Objective(s)

At the end of the lesson, students should be able to identify ways recyclable materials can be separated and sorted at a materials recovery facility (MRF), including these four: conveyor belts, blowers, flotation, and magnetism.

Instructional Resources

Background:

Before starting this lesson, you may want to view the What is STEM? video below.

What is STEM Education

Many communities transport collected recyclables to a materials recovery facility (MRF, commonly referred to as a “murf”). A MRF is a facility for sorting, separating, and processing trash and recyclables. A MRF may take commingled recyclables such as aluminum and steel cans, plastic jugs, glass bottles, and newspapers and separate them by hand or use mechanical processing. Some MRFs process discarded waste, and extract and separate recyclables from trash that will be landfilled or incinerated.

Here's an example: Homeowners place their trash and recyclables in bags or bins at the curb. The recyclable materials are either collected all together or separated, depending on the community. The collection truck then hauls the materials to the MRF for further processing. At some MRFs, materials go across a screen, separating lightitems like paper,and heavy materials, like glass. An eddy current pulls out aluminum cans. Magnetic separators gather up metals, like steel and tin. Water can separate items that float from those that sink, while fans blow light material like certain types of paper away from the other items in the waste stream. Other types of recycled paper areusually hand picked and separated by grade or type of paper. Additionally, plastic bags are often removed by hand. Both paper and plastic bags can clog the machinery, making human separation necessary. Workers constantly ensure that materials are appropriately sorted during the entire process.

The following photo essay, which you can share with students as part of this lesson, provides more information. (You can also access the PPT version of this essay under Teaching Guides so that you can customize it for your classroom needs.)

Solid Waste Photo Essay

After sorting the recyclables according to the manufacturers' end use specifications, the materials are usually baled and loaded onto trucks for transport. These raw materials go to businesses that perform the next step in the recycling process, manufacturing new products.

The new products are then transported to stores for the final step in the recycling process -- purchase by the consumer.

Materials:

Large bag of clean “garbage” (many types and sizes of paper, assorted plastic containers, aluminum cans, aerosol and other steel cans)
Paperclips
Bits of wire
Large magnet
Wide shallow dish pan
Water
Large box lid
Stop watch or clock
Fan

Procedure:

To inform your instruction, you may want to view the Demonstrations video below.

Demonstration video

Optional Demo

Teacher will collect a pen or pencil from each student.
Teacher lines up pens and pencils across the front edge of a table or desk in an orderly fashion.
Instruct students that when teacher says,“Go!”, they are to walk forward, find their own pen/pencil, and return to their seats.
Time the procedure.
Repeat the activity, but this time commingle (mix) all of the pens/pencils into one heap.
Time the procedure again.
Compare the times and discuss why there is a difference.
Relate this activity to sorting recyclables from trash and from other recyclables. When we put items in the recycling bin, they are commingled, just like the pencils in step 5. MRFs have the job of separating the recycling, which as we saw in step 7 can be a challenge.
Explain that most MRFs use manual and mechanical methods to sort recyclables. You can share the following photo essay with students to explain further. (You can also access the PPT version of this essay under Teaching Guides so that you can customize it for your classroom needs.)

Solid Waste Photo Essay

Lesson Procedure

Have a bag of clean “garbage” materials ready, including the examples listed in the “Materials” section of this lesson.
Distribute copies of the student sheet, “MRF Notes,” provided at the end of this lesson. Ask students to record predictions about which materials could be sorted at a MRF by conveyor belts, by wind, with water (float or sink), and with magnets.
Tell the students to then perform or watch the following simulations and record the actual results.
TRIAL 1: Conveyor Belt Simulation

Empty the clean materials from the bag in a pile onto the large box lid. Gently shake the lid to show how some MRFs use conveyor belts to move the materials and to separate them. Larger and lighter materials, like empty soda cans, or paper bounce on the conveyor belt and tend to gather together, while smaller or heavier items do not bounce so easily and settle to the bottom.

Record the results.

TRIAL 2: Blower Simulation

All the participants should wear safety goggles. Turn on the fan. Drop each object in front of the blowing fan. What happens to each object? Record the results. The wind should blow the paper and plastic, not the heavier items. Discuss how some MRFs use blowers to sort plastic and paper.

TRIAL 3: Flotation Simulation

Fill a dish pan with water. Choose a few recyclable samples and drop them into the water, one at a time. Does the item float or sink? Record the results. Relate this to how MRFs may use flotation for sorting.

TRIAL 4: Magnetic Removal Simulation

Test each material for magnetic properties. Record the results. Relate this to how MRFs use magnets to sort ferrous (containing iron) metals. You may wish to heap the recyclables in one pile, and attempt to 'pull out' the ferrous metals using only one magnet.

Have students compare their predictions with the actual results.
Discuss the advantages and disadvantages of each procedure (conveyor belts, blowers, flotation systems, and magnets) that may be used at MRFs. Include in the discussion the use of manual processing systems and how the two (mechanical and manual) interact.
Explain that MRFs usually use multiple procedures to separate waste, but may use them in different orders or combinations depending on the materials in the waste stream and the resources available.
Have students design their own system by combining any of the procedures they have tested. They can use all of the procedures or just some of them. If you have time and other materials, students could research or create other procedures used to separate waste.
Have students test their system and record their results.
Discuss. Ask students why they picked the procedures they did and why they decided to put them in a specific order.

Extensions

These Web-directed research activities correlate with the Keep America Beautiful “Clean Sweep U.S.A.” web site targeted to grades 6-8, and are designed to expand on the objectives in this lesson. The web site can be found at CleansweepUSA.org.

Define a “materials recovery facility.” Describe the “recycling loop.” Have students site online sources.
Select one recycled material (e.g., paper, plastic, aluminum, steel, glass, tires, cars, computers, cell phones etc.) and report on it. What is the recycling rate? What new products are made from the recycled material? List other facts that make it valuable to recycle.
Find the recycling guidelines for yourcommunity. Who is responsible for recycling and recycling education? What are considered contaminants?
Find out how recyclables in your community are collected and sorted. Where is the closest materials recovery facility? What does it take to site a materials recovery facility? Are they regulated? Who regulates them?

Assessments and Rubrics

If you are interested in learning how to make your own rubric for this or other lessons, you may be interested in watching the How to Make a Rubric video below.

How to Make a Rubric

Or, you can choose to use or customize the one created for this lesson plan below.

Recycling Rules Rubric (XLS)

Recycling Rules Rubric (PDF)

Have students describe a materials recovery facility (MRF), and identify four sorting techniques to separate recyclable materials.
Ask students to explain why MRFs employ different sorting techniques.
Have students compare manual and mechanical sorting techniques and list pros and cons for each.
Ask students to compare and contrast commingled vs. source separated waste streams.

External Resources

American Chemistry.com: Information on plastics recycling

American Forest& Paper Association: Recycling Quiz

Can Central

Earth 911.com: U.S. environmental glossary and search by zip code for local recycling opportunities

Glass Packaging Institute

Institute of Scrap Recycling Industries Inc.

International Solid Waste Association

Solid Waste Management in Cape Town South Africa

Steel Recycling Institute

U.S.Environmental Protection Agency Office of Solid Waste

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