Recycling Sorter

Students will learn about the challenges waste management centers face and different methods they use to sort recycling. In small teams, students will brainstorm and design a system to sort a mixed-up recycling bin.

  • Issues surrounding single-stream recycling and how materials recovery facilities (MRFs) work.
  • How they can support effective recycling in their community.
  • Creative technology being used to clean up trash, litter, and pollution.

Age Levels: 8 – 14

Lesson Plan Overview

Build Materials (For each team)

Required Materials

  • Four smaller bins or cardboard boxes to separate recyclables
  • Broken-down cardboard boxes or other sheets of cardboard
  • Roll of paper (wrapping, art) or shelf liner sheets (used for conveyer belt)
  • Loose netting

Optional Materials

  • Fans or hair dryers
  • Ladder or step stool (to allow changes in height for chutes, etc.)
  • Magnetic wands or other large magnets

Testing Materials

  • Variety of clean, dry recyclables (plastics, glass, metal/aluminum cans, and paper) in a large recycling bin or box
  • Long table or a few short tables placed together

Materials

  • Variety of clean, dry recyclables (plastics, glass, metal/aluminum cans, and paper) in a large recycling bin or box
  • Long table or a few short tables placed together

Process

Place design on a long table (or a few short tables placed together), add recyclables to the design and document how well each design sorts the recyclables into separate bins.

Inside a Recycling Facility

Every day at the Sims Municipal Recycling facility in Sunset Park, Brooklyn, roughly 800 tons of recyclables are sorted. (Video 4:43)

Source: Science Friday YouTube Channel

Check out these cool factory robots on robots.ieee.org

Yumi: https://robots.ieee.org/robots/yumi/

Nextage: https://robots.ieee.org/robots/nextage/

AI-driven Sorting Robots

MIT and CSAIL* developed “RoCycle” a robot that can automatically sort recyclables. http://news.mit.edu/2019/mit-robots-can-sort-recycling-0416

Source MIT News

Design Challenge

You are an engineer working to design a system to sort a mixed-up recycling bin. The goal is to gain an understanding of the challenges waste management centers face and different methods they use to sort recycling.

Criteria

  • Separate recyclables into four categories (plastic, glass, metal and paper)

Constraints

  • You can help run the system by acting as part of the machinery design but you cannot handle the recyclables directly.
  • The paper materials must remain dry.
  1. Break class into teams of 2-4.
  2. Hand out the Recycling Sorter worksheet, as well as some sheets of paper for sketching designs.
  3. Discuss the topics in the Background Concepts Section.
  4. Review the Engineering Design Process, Design Challenge, Criteria, Constraints and Materials. If time allows, review “Real World Applications” prior to conducting the design challenge.
  5. Before instructing students to start brainstorming and sketching their designs, ask them to consider the following:
    – Shape and weight of recyclables
    – Are any of the recyclables magnetic?
    – Will gravity play a role in your design?
  6. Provide each team with their materials.
  7. Explain that students must develop a recycling sorter from everyday items. The sorter must separate recyclables into four categories (plastic, glass, metal and paper). The teams can help run the system by acting as part of the machinery design but cannot handle the recyclables directly.
  8. Announce the amount of time they have to design and build (1 hour recommended).
  9. Use a timer or an on-line stopwatch (count down feature) to ensure you keep on time. (www.online-stopwatch.com/full-screen-stopwatch). Give students regular “time checks” so they stay on task. If they are struggling, ask questions that will lead them to a solution quicker.
  10. Students meet and develop a plan for their recycling sorter. They agree on materials they will need, write/draw their plan, and present their plan to the class. Teams may trade unlimited materials with other teams to develop their ideal parts list.
  11. Teams build their designs.
  12. Test the recycling sorter designs placing each design on a long table (or a few short tables placed together), adding recyclables and documenting how well each design sorts the recyclables into separate bins.
  13. As a class, discuss the student reflection questions.
  14. For more content on the topic, see the “Real World Applications” and “Digging Deeper” sections.

Teamwork

  • Begin by having students work in small teams of 3-4 to brainstorm solutions and draw a diagram of their planned sorting machine on paper. Each team then decides on their best ideas, and takes turns sharing their ideas with the class.
  • As a class, vote for the best team ideas. Elect one member from each team to work together to build the sorter based on the combined best ideas. The remaining students observe and advise the building team.
  • The design team presents the design and demonstrates the sorting machine.

Student Reflection (engineering notebook)

  1. What were the characteristics (magnetism, weight, etc.) of each type of recyclable that allowed it to be sorted? What other characteristics and methods of sorting do you think could be used?
  2. How important do you think human eyes and hands would be to a single-stream sorting process? When and for what materials do you think people would be needed most?
  3. Given the advantages and disadvantages of single-stream recycling, do you think it’s a worthwhile system? Why or why not?
  4. What do you think could be done to improve recycling where you live?

Time Modification

The lesson can be done in as little as 1 class period for older students. However, to help students from feeling rushed and to ensure student success (especially for younger students), split the lesson into two periods giving students more time to brainstorm, test ideas and finalize their design. Conduct the testing and debrief in the next class period.

Divide into teams
Review the challenge and criteria constraints
Brainstorm possible solutions (sketch while you brainstorm!)
Choose best solution and build a prototype
Test then redesign until solution is optimized
Reflect as a team and debrief as a class

What is Single-Stream Recycling?

Zoran Photographer-bigstock.com

Single-stream (or no-sort) recycling is a system in which recyclables, such as paper, metals, plastics, and glass, are mixed together rather than being sorted by citizens before collection. In a single-stream recycling system, people don’t need to separate their recyclables. Instead, all recyclables are collected in a single truck, and then are separated for reuse at a materials recovery facility (MRF). At a MRF, materials are separated using conveyor belts and multiple separation methods. Once the materials are separated, they are collected together and sold for reuse.

Advantages

Single-stream recycling means there are fewer barriers to recycling for citizens. The hope  is that since it takes less effort to recycle, more people will do it, and more materials will  be collected. In Minneapolis, the switch to single-stream recycling lead to a 29 percent  increase in recycled materials within a few years.

Single-stream recycling also makes the collection of recyclable materials cheaper, easier,  and safer. Recyclables can be collected in one single-compartment truck, which costs  much less than multiple-compartment trucks. Collecting recyclables in a single  compartment also makes the job easier and safer for materials collectors.

Disadvantages

Reamolko-bigstock.com

Single-stream recycling comes with a number of disadvantages as well. Since recyclables need to be sorted before they can be sold, the cost to process them is higher. It costs about $3 more per ton to process recyclables in a single-stream system.

There’s also a higher chance that recyclables will become contaminated. Contamination  can happen when materials that can’t be recycled get mixed in with those that can. This  can slow down or stop sorting at MRFs. Broken glass and wet paper can also get mixed in  with other recyclables. This can mean that the recycled materials are worth less when sold. It can even mean that some materials that would normally be recycled may end up  in the landfill.

How It Works

132424148-bigstock.com

MRFs use an elaborate mix of machinery to sort materials. Some of these machines are fairly basic and mechanical, while others use newer and more sophisticated. Materials are spread out on a conveyor belt, then moved through a series of machines, such as a cardboard screen, a fines screen (which sorts out materials less than 2 inches long), a newspaper screen, magnets, and optical sorters that can detect and remove different types of plastics, and various other sorters and balers. Technologies like infrared sorters can be used to identify different kinds of plastic, image processing systems can sort materials  based on color, and electromagnetic sensing technology can be used to eject metal  objects from the main conveyor belt. At some point in most systems, people are also  needed to remove unwanted objects by hand.

How You Can Help

When a single-stream recycling system is running smoothly, it can mean saving more  recyclables from the landfill and helping to keep recycling profitable. If you live in an area  that uses single-stream recycling, you can help make this happen by closely following the  recycling rules and guidelines put out by your local recycling center. Following these rules  means recyclables will arrive at the MRF facility in the best possible state for sorting.  Some simple rules to follow are making sure loose plastic bags and unrecyclable plastics  stay out of the recycling bin, and making sure that your recyclables are rinsed and  allowed to dry, since wet paper and cardboard can’t be recycled.

  • Chute: A steep, narrow slope down which things can slide.
  • Constraints: Limitations with material, time, size of team, etc.
  • Conveyor Belt: A continuous moving band of fabric, rubber, or metal used for moving objects from one place to another.
  • Criteria: Conditions that the design must satisfy like its overall size, etc.
  • Engineers: Inventors and problem-solvers of the world. Twenty-five major specialties are recognized in engineering (see infographic).
  • Engineering Design Process: Process engineers use to solve problems.
  • Engineering Habits of Mind (EHM): Six unique ways that engineers think.
  • Iteration: Test & redesign is one iteration. Repeat (multiple iterations).
  • Materials Recovery Facility (MRF): Facility where recycling materials are separated using conveyor belts and multiple separation methods. Once the materials are separated, they are collected together and sold for reuse.
  • Prototype: A working model of the solution to be tested.
  • Recycle: Practice of reusing materials in existing products to create new ones.

Internet Connections

Recommended Reading

  • See Inside Recycling and Rubbish by Alex Frith (ISBN: 978-1409507413)
  • Tracking Trash: Flotsam, Jetsam, and the Science of Ocean Motion (Scientists in the Field Series) by Loree Griffin Burns (ISBN: 978-0547328607)
  • Plastic, Ahoy!: Investigating the Great Pacific Garbage Patch by Patricia Newman and Annie Crawley (ISBN: 978-1467712835)
  • What a Waste: Trash, Recycling, and Protecting our Planet by Jess French (ISBN: 978-1465481412)

Writing Activity

The Baltimore Harbor Trash Wheel Project, affectionately known as Mr. Trash Wheel, uses a turning wheel to scoop trash and debris out of the water and collect it into a dumpster barge. The current from the Jones Falls River, which flows into the harbor, powers the trash-scooping wheel. On days when the current isn’t strong enough to turn the wheel, solar panels provide backup power. Mr. Trash Wheel has collected more than 999 tons of trash since May 9, 2014. What parts of the Baltimore Harbor Trash Wheel’s design do you think are the most helpful and important? Why do you think it is so important to a city like Baltimore? Think about where you live. Are there areas of your community that could use an inventive cleaning machine? What sort of cleaning machine would you create to help your community? What benefits would it bring? What challenges would it face?

Alignment to Curriculum Frameworks

Note: Lesson plans in this series are aligned to one or more of the following sets of standards:  

Next Generation Science Standards

K-ESS3-3 Earth and Human Activity

  • Communicate solutions that will reduce the impact of humans on the land, water, air, and/or other living things in the local environment.

MS-LS2-5 Ecosystems: Interactions, Energy, and Dynamics

  • Evaluate competing design solutions for maintaining biodiversity and ecosystem services

ETS1: Engineering Design 

  • ETS1.A: Defining and Delimiting an Engineering Problem 
  • ETS1.B: Developing Possible Solutions 
  • ETS1.C: Optimizing the Design Solution 

ETS2: Links Among Engineering, Technology, Science, and Society

  • ETS2.A: Interdependence of Science, Engineering, and Technology 
  • ETS2.B: Influence of Engineering, Technology, and Science on Society and the Natural World

Standards for Technological Literacy – All Ages

The Nature of Technology

  • Standard 3. Students will develop an understanding of the relationships among technologies and the connections between technology and other fields of study.

Technology and Society

  • Standard 5. Students will develop an understanding of the effects of technology on the environment.

Design

  • Standard 9: Students will develop an understanding of engineering design.
  • Standard 10: Students will develop an understanding of the role of troubleshooting, research and development, invention and innovation, and experimentation in problem solving.

Abilities for a Technological World

  • Standard 11: Students will develop abilities to apply the design process.
  • Standard 13. Students will develop abilities to assess the impact of products and systems.

In a single-stream recycling system, a series of machines is used to sort mixed recyclables into their correct categories. In this activity, you will work in teams and as a class to design a system to sort mixed recyclables (plastics, glass, steel cans, and paper) into their four categories.

1) Working in teams of 3 or 4, brainstorm ways to separate each type of recyclable from the mixed bin. You should feel free to get up and examine the different materials available. Your team is allowed to help run the system, acting as part of the machinery (students can pull materials on a conveyor belt, bump and agitate materials, etc.), but you cannot directly handle the recyclables. The paper recyclables are also required to remain dry.

2) As a team, choose your best ideas for separating each type of recyclable. Then combine these ideas together to create a full system for sorting the entire bin.

3) Sketch out your design and present your team’s plans to the class.

4) The class will vote on the best ideas and create a new, final design.

5) A designated member of each team will work to build this system using the available materials.

6) The building team will test the system. Watch to see how the system works.

7) Discuss with the class what worked and what didn’t. Brainstorm ways to improve the system and decide what changes should be made.

8) The building team will make the changes and test the improved system.

9) Discuss with the class what worked and what didn’t. What changes helped improve the system? What changes didn’t? If you were going to build a third version, what other changes would you make?

Reflection

1) What were the characteristics (magnetism, weight, etc.) of each type of recyclable that allowed it to be sorted? What other characteristics and methods of sorting do you think could be used?

 

 

 

 

2) How important do you think human eyes and hands would be to a single-stream sorting process? When and for what materials do you think people would be needed most?

 

 

 

 

3) Given the advantages and disadvantages of single-stream recycling, do you think it’s a worthwhile system? Why or why not?

 

 

 

 

4) What do you think could be done to improve recycling where you live?

 

Lesson Plan Translation