Design for Recycling

If you were to contact a group of recycling professionals, as one recent survey did, and ask them to list all the ways that consumer product manufacturers drive them crazy, you’d probably hear a lot about “shrink sleeves”—those full-body, shrink-to-fit plastic labels found on beer cans, yogurt containers, and any number of other items.

Because these sleeves fool the infrared sensors that are supposed to identify plastics by polymer type in recycling facilities (see  “Recycling meets reality”), it becomes difficult to sort the items correctly. And that can lead to all kinds of downstream contamination issues for the recycling facilities that are supposed to turn bales of “sorted” plastic and cans into reasonably pure materials for new products.

The shrink sleeve problem, in turn, is just one particularly annoying example of a much larger issue: complex, multi-material packaging that is a nightmare to disentangle at recycling time. Examples include the familiar blister packs (a mix of cardboard and clear plastic used to market small consumer items such as pens or scissors); unit-dose packs (the push-through, foil-and-plastic variant of blister packs often used for physician samples and over-the-counter pills); cardboard oatmeal containers with plastic or metal tops; plastic spray bottles with metal parts in the sprayer—on and on. Even the humble potato chip bag can have multiple layers of material. Any one of these items is easy enough to take apart in the laboratory, but no one has yet figured out how to do so at an acceptable cost on an industrial scale.

“We get a lot of materials that our customers think are recyclable, but are very difficult for us to deal with,” says Pete Keller, vice president of the Arizona-based recycling giant Republic Services.

A major headache for recyclers is complex packaging that incorporates multiple materials

The good news is that the drawbacks of single-use, hard-to-recycle packaging have begun to draw wider attention. A combination of environmental awareness, consumer preferences, government regulation, and manufacturers’ cost-cutting has sparked a movement toward minimalist packaging that emphasizes simplicity and sustainability.

Closely allied with that effort is a design-for-recycling movement that seeks to eliminate recycling problems from the start. Right now, explains Dylan de Thomas, “the marketers at company X, Y, or Z come up with a great idea,” and then it’s implemented by packaging engineers who were never trained to think about what happens once their creations are discarded. “They don’t realize that when they use this ink, this adhesive, this type of label presented in this way, it essentially renders the product unrecyclable,” says de Thomas, who handles industry collaboration for the Recycling Partnership, a nonprofit based in Falls Church, Virginia, that funnels industry money into recycling-related grants and research projects. It’s not that the better alternatives are any more expensive or difficult to implement, he says. “It’s that the designers are just unaware of them.”

But in 2018, says de Thomas, an industry group, the Association of Plastics Recyclers in Washington, D.C., tried to raise awareness with a  design guide for plastics recyclability. It’s a 76-page technical resource that goes into numbing detail about labels, glues, fittings—everything that helps or hurts the recyclability of eight different polymer types.

Granted, there are some problems that the guidelines can’t solve. After all, says Marco J. Castaldi, a chemical engineer at the City College of New York, who wrote about sustainable waste management for the 2014 Annual Review of Chemical and Biomolecular Engineering, packaging isn’t just about branding and display. Especially when it comes to food, says Castaldi, containers like the potato chip bag are complex and multilayered because they have to meet strict performance standards. “The side of the plastic that touches the product has to be inert,” he says, with no bad flavors leaching in and no adverse reactions with the salt. Meanwhile, he says, “the side that is exposed to the air or the environment can’t allow ultraviolet light or oxygen to diffuse in,” since either one will cause the oils to go rancid. And in between, he says, “you have a layer that maybe has a little bit of metal in it” to add structural strength and another barrier to diffusion. Finding cheap and easily recyclable alternatives that can still deliver this kind of performance remains a major research challenge, says Castaldi.

Nonetheless, says de Thomas, the plastic guidelines can help a lot. Uptake has been slow—“the document needs to be used far more often in my opinion,” he says—but the idea is catching on. In September 2020, for example, the Aluminum Association released a similar design guide for recyclability. (Plastic shrink sleeves can create contamination problems with cans, too.) Likewise, he says, “there are design considerations that can make it challenging to recycle various things made out of paper.” So a major industry group, the  American Forest & Paper Association, is working with de Thomas’s team to develop its own guidelines for recyclability. “It's something that just needs to be adopted,” he says.

This article originally appeared Oct. 1, 2020, in Knowable Magazine, an independent journalistic endeavor from Annual Reviews. Sign up for the newsletter.

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