Understanding the life cycle of recycled cardboard


For people who care about conserving resources, recycling is a given. But what really happens to all the cardboard and paper dumped in curbside recycling bins?
Mike Gunderson is general manager of WestRock, the 100-year-old paper mill that recycles cardboard picked up across the Twin Cities by Eureka Recycling. The mill yard at University and Vandalia receives mountains of used cardboard and paper daily, while inside the mill operates 24 hours a day.
Gunderson said, “Our volume of incoming fiber goes up every year, but there has been a larger than usual uptick in 2020-21. Curbside recycling volume has gone up a lot. People are shopping more online, and they’re ordering more take-out food, too.
“On the other hand, we have gotten substantially less paper from schools and brick-and-mortar retail since the pandemic started. Overall there has been a shift in the streams of where cardboard and paper come from.”
WestRock receives cardboard and paper from more than 600 sources. The largest quantity comes from Eureka Recycling, which contributes about 25% of the total incoming fiber. Gunderson estimates that approximately 400,000 tons of material are brought to WestRock and recycled every year. He said, “About 65% of all recycled fiber in the state of Minnesota ends up here.”

The long and the short of it
Next time you fill your cereal bowl, take a look inside the box. Every box is made from a mix of fiber lengths. At WestRock, two types of finished recycled paper leave the mill on rolls as large as 11 feet wide: coated recycled cardboard that will be made into cereal, pasta, and pharmaceutical boxes, and corrugated medium (the fluted layer that goes between paper sheets to make cardboard).
Gunderson explained, “The fibers in cardboard can be recycled many times, but they get shorter every time they go through the process. We get millions of boxes entering our system every day. The cereal-type boxes (the ones that get printed on) are made up of half long and half short fibers. The corrugated medium is made up of all long fibers.”

Recycling 101
With curbside pick-up contributing so much cardboard these days, waste haulers are finding all kinds of things in recycling bins that can cause problems. Legitimate recyclables are often mixed up with items from peoples’ homes and kitchens. Dirty diapers and kitchen scraps can contaminate cardboard, making it unfit for recycling. Holiday lights and batteries cause major problems.
Gunderson’s #1 nemesis is plastic bags. He said, “Plastic bags, cereal wrappers, and plastic films have to be taken to a separate big-box store like Target or CUB where they have drop-off bins. Plastic bags are not recyclable as part of the single stream system. Do not put them in your curbside recycling bin.”

From solid to liquid to
solid again
Surprisingly, the packing tape and staples embedded in most cardboard boxes don’t cause a problem in the recycling process. As the saying goes, they come out in the wash. Styrofoam packing material must be removed, however, and all cardboard boxes should be flattened.
Gunderson explained, “We move about 1,200 tons of waste material from the yard every day. Bales and loose waste are loaded into a circular tank containing water. Called a hydrapulper, this machine has a powerful agitator at the bottom that breaks everything down into small pieces. The pulp mass looks like oatmeal.
“This is the first stage of ‘de-trashing,’ where anything that doesn’t turn into pulp gets pulled out: shredded metal, broken glass, tape, staples, and other non-fiber materials. Multiple stages of screening remove remaining contaminants down to an 8,000 of an inch. In the last stage, the slurry is sent through an industrial magnet.
“At the end of the day, when the slurry has been washed, pressed, and dried, we have produced about 1,100 tons of recycled paper. We divert a lot of waste from the landfill.”

Recycling has changed
over time
In 2014, the city of St. Paul did away with having residents sort their recyclables. The goal was to get more people to recycle, and it worked. Gunderson said, “On a net basis, more product is being recycled now. We’ve had to invest in improved sorting technology, as the quality of recyclables has gone down – but there is less volume going to the landfill.”
Eureka Recycling Director of Community Engagement Katrina Lund underscored that. She said, “Even with the higher contamination rate, recycling has real benefits. In the case of cardboard, we are conserving trees by recycling. It takes about 25% less energy to recycle paper than it does to make virgin paper. Recycling produces jobs, and supports the local economy.”
To see how Eureka and WestRock work in partnership, go to https://eurekarecycling.org. Scroll down to the bottom of the page to view “The Story of a Cereal Box.” The video shows how a cereal box is made new again in about one month’s time.
Lund said, “As a mission-based, zero-waste recycler, we believe that waste is preventable. Our goal is ultimately to prevent waste.”
Best-practice recycling
The following items are not recyclable: plastic bags, plastic containers #3, #4, #6, or #7, plastic containers larger than 3 gallons, black plastic, plastic storage bins, laundry basket or toys, shredded paper, food, liquid or other compostable material, Styrofoam, batteries, electronics, light bulbs, scrap metal, hazardous waste, sharps, or needles.
And last but not least, egg cartons (Styrofoam or paper) are not recyclable. Why not the paper ones? They are a product that has reached the end of its recycling life; the fibers have gotten too short to be used again.
More at https://eurekarecycling.org/recycling-services/recycling-guidelines/


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