Better recycling through chemistry

carpet bundle
Aquafil
A carpet bundle prepared for processing.

While it's true that any type of recycling reduces the need for fossil fuels and reduces the amount of waste that continues to taint our landscapes and our oceans, not all recycling is the same.

Looking specifically at plastics, most plastics are recycled mechanically, which means they are shredded and then melted and pelletized so that they can be reused as recycled plastic.

While this is a relatively simple and inexpensive approach, it introduces a number of compromises and is technically considered downcycling, because there is a loss of quality each time the material is processed. This means that there are a finite number of times the material can be recycled.

A number of factors cause this, primarily contamination, as different types of plastics are difficult to separate in the recycling stream. But even in a "pure stream" of a single plastic, additives can be contained within the plastics, including coloring agents, along with additional chemicals such as oils or cleaning products, some of which might be toxic, that could have been added either in production or during use.

Today a higher bar is available, at least for certain plastics, one that a number of leading companies are already committing to. This is known as depolymerization, which is, in essence, chemical recycling.

With depolymerization, you break the plastic down to its original chemical building blocks known as monomers, which can be used to make new plastic that is virtually identical to the virgin feedstock that had come from fossil fuels.

Safety concerns are among the motivations behind the European Union's Plastics Recycling Plan for 2030, which strongly encourages chemical recycling, while aiming to double current recycling rates at the same time. But recycling plastic through depolymerization is not only safer, it produces better quality products, with mechanical strength and all other properties identical to virgin plastic, in any color. More important, these plastics can be recycled indefinitely, which means they are more sustainable. In addition, in the places where they are available, these materials are already cost-competitive with virgin resin.

The Italian company Aquafil, a leading global producer of nylon yarns for carpeting and apparel, developed its Econyl fiber back in 2011. This is 100 percent recycled nylon that is processed back to its base monomer caprolactam. Aquafil has a dedicated facility in Slovenia that performs this operation. While the original feedstock supply came from post-industrial waste, such as mill waste, the company later made a splash by initiating a program to retrieve discarded nylon fishing nets from the ocean and turning them back into virgin nylon.

Now, the company has taken another huge step with the opening of a carpet recycling facility in Phoenix. In essence, it's a collection and pre-processing facility that produces raw feedstock from waste. Discarded carpeting is being retrieved from landfills or collected under California's carpet stewardship law. The law is based on producer responsibility principles "to ensure that discarded carpets become a resource for new products." The carpeting is prescreened to ensure that only carpeting made from Nylon 6 is used. It is then put through a series of processes — dry shredding, wet scrubbing, centrifuging — and separated into three distinct streams, none of which go to landfill.

Aquafil
The new Aquafil facility in Phoenix.

The calcium carbonate, used as carpet filler, is removed and sent off to be used for road construction and concrete. The polypropylene, generally used in the backing material, is removed and can be reused to make injection-molded plastic products. About a third of the material is reclaimed nylon that is extruded and pelletized. Those pellets are shipped back to Slovenia where they are put through the final step in the Econyl process to make new virgin nylon. The pellets could be used as is for injection molding, but they would be of lower quality. Aquafil receives better value by returning the material to virgin nylon.

According to Aquafil CEO Giulio Bonazzi, even with the cost and overhead of shipping the material to Slovenia, the overall carbon footprint of the process is 80 percent lower than the process used to create virgin nylon from fossil fuels and the cost is at parity. The company already has plans to build a second recycling facility in Woodland, California. That facility, like the one in Phoenix, will take in 36 million pounds of waste carpeting, which will produce roughly 12 million pounds of nylon feedstock.

Learn more about plastics recycling and reuse at GreenBiz 19 in Phoenix, Feb. 26 - 28. 

"When we have five or six of these facilities, we'll have enough [volume] to build a chemical recycling facility here in the United States," Bonazzi said. This will allow Aquafil to eliminate the step of shipping the resin back to Slovenia, which will further reduce both the carbon footprint and the cost while keeping the entire supply chain here.

It should be noted that nylon is the most common material used in carpeting, responsible for roughly three-quarters of all manufactured carpeting. 

The work goes back nearly two decades, when Aquafil, long a supplier of Interface, sought to respond to then-CEO Ray Anderson's request for a more sustainable product. The two companies worked with the Biomimicry Institute to develop the approach.

Dayna Baumeister, cofounder of Biomimicry 3.8., who was on hand for the grand opening in Phoenix, repeated the question she raised back then: "How is it that nature can recycle all of its nutrients without waste?"

It turns out, as she described in her remarks, three key lessons were learned.

First, living things are made mostly of the same stuff, which, when you think about it, is why eating each other nourishes us. Living things are made from just a few elements on the periodic table (carbon, hydrogen, oxygen and nitrogen). The second thing nature does is that it doesn't turn leaves directly back into leaves; it breaks everything back down to their basic elements, from which many living organisms can draw nourishment. The third thing nature does is to use vast interdependent networks of plants and animals and insects and soil organisms to achieve this highly efficient nutrient recycling.

Aquafil has used all three of these ideas to develop its process. It was somewhat fortuitous that Nylon 6 is made from a single organic monomer, caprolactam. Had the material derived from a more complex molecule — such as the most popular form of nylon on the market, Nylon 6,6, derived from two monomers — it would have been far more difficult to recycle chemically. "You can do it, but with a very low yield, maybe 20-25 percent,” Bonazzi said. Aquafil's Econyl process achieves 100 percent yield.

By returning the carpeting back to caprolactam, Aquafil is creating a material that can be turned into anything made from nylon, including clothing, sporting goods or injection molded products — just like in nature where decaying leaves can become nutrients for anything from new trees to new butterflies.

Bottling up waste

Another company that has developed a chemical recycling process is Montreal-based Loop Industries. It has taken a similar recycling approach with PET (polyethylene terephthalate), a member of the polyester family.

Nelson Switzer, chief growth officer of Loop Industries, told GreenBiz, "If things don’t change, by 2050, plastics could represent 20 percent of global oil consumption, as plastics production increases by 3.6 times its current level."

Unlike Nylon 6, PET is comprised of two monomers — dimethyl terephthalate (DMT) and mono ethylene glycol (MEG) — making it more difficult to depolymerize. According to the Loop Industries website, its proprietary process "allows for all types of waste PET plastic to be upcycled into high purity, food-grade PET plastic, like the kind used in water bottles. That includes the PET plastic found in carpets and opaque bottles, which ends up in landfills today."

The company has signed agreements with several major bottling companies including Coca-Cola, PepsiCo and Evian to provide material for their beverage bottles. Forbes has described Loop Industries as the "Intel Inside" of the plastics industry, as the Loop logo is set to appear on bottles using this process.

According to Switzer, Loop Industries founder and CEO Daniel Solomita and head scientist Hattem Essaddam "spent months in a garage developing a commercial process" for Essaddam's discovery of a process to depolymerize PET. In addition to its apparent ability to chemically recycle PET, "transforming waste PET plastic from a problem into a valuable industrial commodity," the company claims that the process takes place using "zero energy," alluding to the fact that the process requires neither heat nor pressure to break down the PET to its base monomers. That's clearly an overstatement because some energy will be required to collect the material, deliver it to the building and move it through the facility, although if no heat or pressure is required, energy consumption indeed could be quite low.

The company is not yet in production, although it has signed a joint venture agreement with Indorama Ventures Ltd., which will manufacture the PET resin using Loop Industries' patented process. According to the release, this will allow it to "perpetually recycle the ever-increasing amounts of PET plastic and polyester fiber proving the promise of and encouraging the shift to a circular economy."

Initiatives such as Aquafil's Econyl and Project Effective represent a way forward for regenerative products that could improve the environment, in this case by keeping waste out of landfills and reducing carbon footprint with every item produced. It seems possible that in the future, the need for petroleum-based plastics, which already accounts for 4 percent of global crude oil consumption, eventually could be eclipsed by a far more sustainable combination of bio-based and chemically recycled alternatives.