Industrial Recycling: How to Close the Loop?

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How many times have you heard the expression “close the loop”?

In recycling circles, folks have been tossing around the term for some time now. But what do they really mean? Well, it depends on who you ask.

Definitions Differ

Google the terms “closed loop” or “open loop” recycling, and you’ll find some conflicting definitions. For instance:

The Dictionary of Sustainable Management defines “open-loop recycling” as “the conversion of material from one or more products into a new product, involving a change in the inherent properties of the material itself (often a degradation in quality). For example, recycling plastic bottles into plastic drainage pipes.”

On the other hand, the online Business Dictionary defines “closed loop” as a “production system in which the waste or byproduct of one process or product is used in making another product. For example, recycling waste newspaper to make paper-board or other types of paper.”


So is recycling one type of product to make a totally different type of product considered “open loop”? Or is it considered “closed loop”? Or are both definitions perhaps too simplistic?

Another Perspective

The editors at Earth911 have an entirely different take on the subject.

They also define “closed-loop” recycling as “basically a production process in which post-consumer waste is collected, recycled and used to make new products.”

The following video clip explains how computer giant HP Inc. uses a closed-loop recycling program for its printer cartridges:

However, they understand the closed-loop process as encompassing BOTH recycling into the same product AND recycling into a totally different product:

“This process can be as simple as using recycled aluminum to make new cans, or as complicated as weaving reclaimed plastic bottles into polyester for clothing and other products.”

close the loop

A purse made from recycled candy wrappers.

The Consumer Angle

But the folks at Earth911 also differ in their definition in this:

They believe that to truly “close the loop,” new products must be made from recycled materials. But that’s not enough. Consumers must then purchase those new products. “When consumers purchase recycled-content products, they essentially ‘close the loop.’”

Aha. So the editors at Earth911 rely on consumers to close the loop. Interesting.

The Ivory Tower Perspective

What about the people who study recycling for a living (the academics)? How would they define the two recycling terms?

“Open-loop recycling basically means that a material is not recycled indefinitely and is eventually excluded from the utilization loop and becomes waste.”

That’s according to the Dept of Energy and Mineral Engineering at Penn State University.

So, the Penn State guys say an open-loop process occurs whenever a certain material (be it metal, paper, or plastic) can no longer be recycled. Which means it ends up in a landfill.

By this definition, open-loop recycling is simply postponing garbage disposal. “In the long run, a small part of the original resource may be stuck in the loop, but the majority of it becomes disposed of.”

This is where the concept of “downcycling” comes in.


Products recycled in an open loop, result in a material that is typically of lower grade and purity than the original material. In their 2002 recycling manifesto, Cradle to Cradle: Remaking the Way We Make Things, the authors describe how downcycling works:

When plastics other than those found in soda and water bottles are recycled, they are mixed with different plastics to produce a hybrid of lower quality, which is then molded into something amorphous and cheap, such as a park bench or a speed bump… Aluminum is another valuable but constantly downcycled material. The typical soda can consists of two kinds of aluminum: the walls are composed of aluminum, manganese alloy with some magnesium, plus coatings and paint, while the harder top is aluminum magnesium alloy. In conventional recycling, these materials are melted together, resulting in a weaker—and less useful—product.

According to our friends at  Penn State, the bottom line is that open-loop recycling results in eventual downgrading. This renders material non-usable, and contributes to waste generation in the end of the lifecycle. “Open-loop recycling postpones disposal and slows down extraction of new natural resources, but does not provide an ultimate solution to the problem.”

Closed-Loop Recycling

The 111 Navy Chair is made entirely from recycled plastic bottles.

Closed-loop recycling is a more sustainable concept. The Penn State scientists define a truly closed-loop recycling process as one which “can be done indefinitely without degradation of properties.” Here are their criteria for closed-loop recycling:

  • The recycled materials should provide the same quality of the product (no deterioration).
  • There should be no accumulation of contaminants or toxins in the multiple recycling loop. This can make the secondary product less safe.
  • The recycled material should be able to feed the manufacturing process for a different product or industry.
  • Any material that cannot be recycled, or any by-product in the manufacturing process, should return to the environment without causing harm. (In other words, all waste must be biodegradable.)

Here’s another example of how one company recycles rubber in a closed-loop program:

So, contrary to the editors at Earth911, the Penn State scientists believe the responsibility for “closing the loop” lies not with the consumer purchasing the new product, but with the original manufacturers and reprocessing facilities. These industrial partners need to ensure that: 1) the quality of a recycled material does not deteriorate, and 2) any final waste product is totally biodegradable and non-threatening to the environment.

In the Meantime

Of course, changes of this magnitude require innovative thinking in the design of our products and processes. And it takes time to accomplish these kinds of changes on a grand scale.

Meanwhile (in deference to Earth911), purchasing products made from recycled materials can’t hurt either.



Dictionary of Sustainable Management

Dept of Energy and Mineral Engineering, Penn State University

WebFinance Inc.

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