Single-stream recycling

Single-stream (also known as “fully commingled” or "single-sort") recycling refers to a system in which all paper fibers, plastics, metals, and other containers are mixed in a collection truck, instead of being sorted by the depositor into separate commodities (newspaper, paperboard, corrugated fiberboard, plastic, glass, etc.) and handled separately throughout the collection process. In single-stream, both the collection and processing systems are designed to handle this fully commingled mixture of recyclables, with materials being separated for reuse at a materials recovery facility (MRF).[1][2]

Materials recovery facility in Montgomery County, Maryland

The single-stream option replaces the dual-stream option, which is where people separate certain recyclable materials and place them in separate containers for collection. From an end consumer perspective, single stream is easier to participate in. However, single stream recycling disadvantages, including the output of lower quality plastics and paper to recyclers. This lower quality material, thus has to be processed more downstream. The increased flow of decreased quality recyclables from Europe and North America in part due to single stream recycling was part of China's motivation for launching its Operation National Sword policy.[3]

Advantages
Materials recovery facility in Ann Arbor, Michigan

Proponents of single-stream note several advantages:[4]

  • Reduced sorting effort by residents may mean that more recyclables are moved to the curb and more residents may participate in recycling;[5]
  • Reduced collection costs because single-compartment trucks are cheaper to purchase and operate, collection can be automated, and collection routes can be serviced more efficiently. Single-stream reduced the amount of time it takes for a driver to collect the recyclables, which reduces the driver time on the road.
  • Greater fleet flexibility, which allows single-compartment vehicles to be used to collect recycling, providing greater fleet flexibility and reducing the number of reserve vehicles needed. To avoid confusing customers, a large sign or banner is sometimes used to distinguish when a refuse truck is being used to collect recycling (instead of refuse).
  • Worker injuries may decrease because the switch to single-stream is often accompanied by a switch from bins to cart-based collection.
  • Changing to single-stream may provide an opportunity to update the collection and processing system and to add new materials to the list of recyclables accepted; and
  • More paper grades may be collected, including junk mail, telephone books and mixed residential paper.

Disadvantages

Potential disadvantages of single-stream recycling may include:

  • Initial capital cost for:
    • New carts
    • Different collection vehicles
    • Upgrading the processing facility
  • Processing costs may increase compared to multiple stream systems. Overall, single-stream costs about $3 more per ton than dual-stream.[6]
  • Increase of contamination in the recycling container. Possible reduced commodity prices due to contamination of paper or plastic[7]
  • Increased downcycling of paper, i.e., use of high quality fibers for low-end uses like boxboard because of presence of contaminants;
  • Possible increase in residual rates after processing (chiefly because of increased breakage of glass)[8]
  • Potential for diminished public confidence if more recyclables are destined for landfill disposal because of contamination or inability to market materials.

Single-stream system

A single-stream system is a complex network of machinery that uses a combination of newer and older technologies to sort materials for recycling, including PET, HDPE, aluminum, tin cans, cardboard and paper.

List of equipment used in a single-stream system:

  1. Back Scraping Drum: spreads materials out on a conveyor belt
  2. OCC Screen: sorts cardboard/ old corrugated containers (OCC). Cardboard is sent to the Single Ram Baler to be baled.
  3. Fines Screen: all material except for cardboard go through Fines Screen. Fines Screen sorts out pieces of glass and fine materials less than two inches long. Glass is sent to the Glass Cleanup System for more separating.
  4. News Screen: sorts out newspaper from the rest of the recycling.
  5. Elliptical Separator: sorts 2D objects from 3D objects.
  6. Ferrous Magnet: pulls all ferrous metals to the magnet such as tin cans and steel.
  7. Optical Sorter: reads the containers for PET plastic.
  8. Eddy Current Separator: pulls out all of the aluminum and non-ferrous materials.
  9. Two-Ram Baler: bales everything except for the cardboard and clear film.
  10. Glass CleanUp System: cleans glass coming off fines screen by pulling off all the light fractions.
  11. Closed Door Baler: bales the clear film plastic.
  12. Motion Floor: walking floor bunkers that stores corrugated and mixed paper.
  13. Single Ram Baler: bales all corrugated materials.

By country

United States

Phoenix, Arizona began exploring single-stream recycling in 1989. A contract was awarded to CRCInc in 1992, and its MRF, the first large-scale recycling facility to process commingled materials in North America, began operation in 1993.[9][10] Subsequently, many large and small municipalities across the United States began single-stream programs. As of 2012, there are 248 MRFs operating in the U.S.[11] As of 2013, 100 million Americans were served by single-stream programs.[12]

See also

References
  1. City of Chicago, Illinois. Department of Streets and Sanitation. "What is Single Stream Recycling." Accessed 2013-12-09.
  2. Montgomery County, Maryland. Division of Solid Waste Services, Rockville, MD (2010). "Comprehensive Solid Waste Management 10 Year Plan: 2009-2019." Archived 2011-04-03 at the Wayback Machine p. 3-40.
  3. "Piling Up: How China's Ban on Importing Waste Has Stalled Global Recycling". Yale E360. Retrieved 2020-10-12.
  4. Connecticut Resources Recovery Authority, Hartford, CT (2013-03-28). "The Facts About Single-Stream Recycling."
  5. Diehl, Phil (2013-03-05). "Single-stream system increases recycling". San Diego Union-Tribune. San Diego, CA.
  6. "Paper Recycling: Quality is Key to Long-Term Success". J.Poyry and Skumatz Economic Research Associates.: 32. 2004.
  7. "Sustainable Facilities Tool: Solid Waste System Overview". sftool.gov. Retrieved 1 July 2014.
  8. "Single-Stream Recycling Generates Debate". Recycling Today. Richfield, OH: GIE Media, Inc. 2002-05-22. Archived from the original on 2014-12-16.
  9. Guttentag, Roger M (Jun 1994). "Processing recyclables: What's my line?". World Wastes. 37 (6): 28.
  10. Holt, Diane (2011-12-06). "Mergers and acquisitions in the waste management industry". In Eweje, Gabriel; Perry, Martin (eds.). Business & Sustainability: Concepts, Strategies and Changes. Emerald Group Publishing. p. 112. ISBN 978-1-78052-439-9.
  11. de Thomas, Dylan (2013-11-14). "Single Stream in the West." Presentation at Fall 2013 Meeting of Association of Oregon Recyclers, Portland, OR.
  12. "How It Works: Inside The Machine That Separates Your Recyclables". Popular Science.
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